How to compile a Maven Java with the librarys? [duplicate]

How to compile a Maven Java with the librarys? [duplicate] - java

I have a code base which I want to distribute as jar. It also have dependency on external jars, which I want to bundle in the final jar.
I heard that this can be done using maven-assembly-plug-in, but I don't understand how. Could someone point me to some examples.
Right now, I'm using fat jar to bundle the final jar. I want to achieve the same thing using maven.

Note: If you are a spring-boot application, read the end of answer
Add following plugin to your pom.xml
The latest version can be found at
...
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>CHOOSE LATEST VERSION HERE</version>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>assemble-all</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
...
After configuring this plug-in, running mvn package will produce two jars: one containing just the project classes, and a second fat jar with all dependencies with the suffix "-jar-with-dependencies".
if you want correct classpath setup at runtime then also add following plugin
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
For spring boot application use just following plugin (choose appropriate version of it)
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<fork>true</fork>
<mainClass>${start-class}</mainClass>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>

You can use the maven-shade-plugin.
After configuring the shade plugin in your build the command mvn package will create one single jar with all dependencies merged into it.

Maybe you want maven-shade-plugin, bundle dependencies, minimize unused code and hide external dependencies to avoid conflicts.
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.1.1</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<minimizeJar>true</minimizeJar>
<createDependencyReducedPom>true</createDependencyReducedPom>
<dependencyReducedPomLocation>
${java.io.tmpdir}/dependency-reduced-pom.xml
</dependencyReducedPomLocation>
<relocations>
<relocation>
<pattern>com.acme.coyote</pattern>
<shadedPattern>hidden.coyote</shadedPattern>
</relocation>
</relocations>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
References:
http://maven.apache.org/plugins/maven-shade-plugin/plugin-info.html
http://maven.apache.org/plugins/maven-shade-plugin/shade-mojo.html

actually, adding the
<archive>
<manifest>
<addClasspath>true</addClasspath>
<packageName>com.some.pkg</packageName>
<mainClass>com.MainClass</mainClass>
</manifest>
</archive>
declaration to maven-jar-plugin does not add the main class entry to the manifest file for me.
I had to add it to the maven-assembly-plugin in order to get that in the manifest

You can use the onejar-maven-plugin for packaging. Basically, it assembles your project and its dependencies in as one jar, including not just your project jar file, but also all external dependencies as a "jar of jars", e.g.
<build>
<plugins>
<plugin>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
<executions>
<execution>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Note 1: Configuration options is available at the project home page.
Note 2: For one reason or the other, the onejar-maven-plugin project is not published at Maven Central. However jolira.com tracks the original project and publishes it to with the groupId com.jolira.

An alternative is to use the maven shade plugin to build an uber-jar.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version> Your Version Here </version>
<configuration>
<!-- put your configurations here -->
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

Read if you want to use the maven-assembly-plugin.
As other answers have already outlined, it seems that the maven-shade-plugin offers more features and is the recommended plugin to build a fat jar, but in case you would like to use the maven-assembly-plugin the following plugin configuration will work.
The answer of #jmj explains that the correct classpath can be setup with an additional maven-jar-plugin, but this will only add the classpath to the original jar and not the fat jar. The information must instead be directly included into the configuration section of the maven-assembly-plugin.
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>3.4.2</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.package.YourMainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>assemble-all</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
When you now run maven package, your normal and fat jar will be created and you can run your fat jar with java -jar yourJar.jar.

Related

java.lang.ClassNotFoundException for SQLite when JDBC dependency included in maven (NetBeans 12.3) [duplicate]

I want to package my project in a single executable JAR for distribution.
How can I make a Maven project package all dependency JARs into my output JAR?

<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
and you run it with
mvn clean compile assembly:single
Compile goal should be added before assembly:single or otherwise the code on your own project is not included.
See more details in comments.
Commonly this goal is tied to a build phase to execute automatically. This ensures the JAR is built when executing mvn install or performing a deployment/release.
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>

You can use the dependency-plugin to generate all dependencies in a separate directory before the package phase and then include that in the classpath of the manifest:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>theMainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
Alternatively, use ${project.build.directory}/classes/lib as OutputDirectory to integrate all JAR files into the main JAR file, but then you will need to add custom classloading code to load the JAR files.

See executable-jar-with-maven-example (GitHub)
Notes
Those pros and cons are provided by Stephan.
For Manual Deployment
Pros
Cons
Dependencies are out of the final jar.
Copy Dependencies to a specific directory
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/${project.build.finalName}.lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
Make the JAR File Executable and Classpath Aware
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>${project.build.finalName}.lib/</classpathPrefix>
<mainClass>${fully.qualified.main.class}</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
At this point the JAR file is actually executable with external classpath elements.
java -jar target/${project.build.finalName}.jar
Make Deployable Archives
The JAR file is only executable with the sibling ...lib/ directory. We need to make archives to deploy with the directory and its content.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<id>antrun-archive</id>
<phase>package</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<target>
<property name="final.name" value="${project.build.directory}/${project.build.finalName}"/>
<property name="archive.includes" value="${project.build.finalName}.${project.packaging} ${project.build.finalName}.lib/*"/>
<property name="tar.destfile" value="${final.name}.tar"/>
<zip basedir="${project.build.directory}" destfile="${final.name}.zip" includes="${archive.includes}" />
<tar basedir="${project.build.directory}" destfile="${tar.destfile}" includes="${archive.includes}" />
<gzip src="${tar.destfile}" destfile="${tar.destfile}.gz" />
<bzip2 src="${tar.destfile}" destfile="${tar.destfile}.bz2" />
</target>
</configuration>
</execution>
</executions>
</plugin>
Now you have target/${project.build.finalName}.(zip|tar|tar.bz2|tar.gz) which each contains the jar and lib/*.
Apache Maven Assembly Plugin
Pros
Cons
No class relocation support (use maven-shade-plugin if class relocation is needed).
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<archive>
<manifest>
<mainClass>${fully.qualified.main.class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.bulid.finalName}-jar-with-dependencies.jar.
Apache Maven Shade Plugin
Pros
Cons
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<shadedArtifactAttached>true</shadedArtifactAttached>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>${fully.qualified.main.class}</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.build.finalName}-shaded.jar.
onejar-maven-plugin
Pros
Cons
Not actively supported since 2012.
<plugin>
<!--groupId>org.dstovall</groupId--> <!-- not available on the central -->
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<executions>
<execution>
<configuration>
<mainClass>${fully.qualified.main.class}</mainClass>
<attachToBuild>true</attachToBuild>
<!-- https://code.google.com/p/onejar-maven-plugin/issues/detail?id=8 -->
<!-- classifier>onejar</classifier -->
<filename>${project.build.finalName}-onejar.${project.packaging}</filename>
</configuration>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
Spring Boot Maven Plugin
Pros
Cons
Add potential unnecessary Spring and Spring Boot related classes.
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
<configuration>
<classifier>spring-boot</classifier>
<mainClass>${fully.qualified.main.class}</mainClass>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.bulid.finalName}-spring-boot.jar.

Taking IAdapter's answer and reformatting it, we have:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
Next, I would recommend making this a natural part of your build, rather than something to call explicitly. To make this a integral part of your build, add this plugin to your pom.xml and bind it to the package lifecycle event. However, a gotcha is that you need to call the assembly:single goal if putting this in your pom.xml, while you would call 'assembly:assembly' if executing it manually from the command line.
<project>
[...]
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
[...]
</plugins>
[...]
</build>
</project>

Use the maven-shade-plugin to package all dependencies into one über-JAR file. It can also be used to build an executable JAR file by specifying the main class. After trying to use maven-assembly and maven-jar, I found that this plugin best suited my needs.
I found this plugin particularly useful as it merges the content of specific files instead of overwriting them. This is needed when there are resource files that are have the same name across the JAR files and the plugin tries to package all the resource files.
See the example below:
<plugins>
<!-- This plugin provides the capability to package
the artifact in an über-JAR file, including
its dependencies and to shade - i.e. rename -
the packages of some of the dependencies. -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.4</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<artifactSet>
<!-- Signed JAR files-->
<excludes>
<exclude>bouncycastle:bcprov-jdk15</exclude>
</excludes>
</artifactSet>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<!-- Main class -->
<mainClass>com.main.MyMainClass</mainClass>
</transformer>
<!-- Use resource transformers to prevent file overwrites -->
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>properties.properties</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.XmlAppendingTransformer">
<resource>applicationContext.xml</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/cxf/cxf.extension</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.XmlAppendingTransformer">
<resource>META-INF/cxf/bus-extensions.xml</resource>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>

You can use the maven-shade plugin to build an über JAR file like below:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

I have long used the Maven assembly plugin, but I could not find a solution to the problem with "already added, skipping". Now, I'm using another plugin - onejar-maven-plugin. An example is below (mvn package builds the JAR file):
<plugin>
<groupId>org.dstovall</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.3.0</version>
<executions>
<execution>
<configuration>
<mainClass>com.company.MainClass</mainClass>
</configuration>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
You need to add a repository for that plugin:
<pluginRepositories>
<pluginRepository>
<id>onejar-maven-plugin.googlecode.com</id>
<url>http://onejar-maven-plugin.googlecode.com/svn/mavenrepo</url>
</pluginRepository>
</pluginRepositories>

You can add the following to your pom.xml file:
<build>
<defaultGoal>install</defaultGoal>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.1</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.mycompany.package.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>com.mycompany.package.MainClass</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Afterwards you have to switch via the console to the directory, where the pom.xml file is located. Then you have to execute mvn assembly:single and then your executable JAR file with dependencies will be hopefully build. You can check it when switching to the output (target) directory with cd ./target and starting your JAR with a command similar to java -jar mavenproject1-1.0-SNAPSHOT-jar-with-dependencies.jar.
I tested this with Apache Maven 3.0.3.

You can use maven-dependency-plugin, but the question was how to create an executable JAR file. To do that requires the following alteration to Matthew Franglen's response (btw, using the dependency plugin takes longer to build when starting from a clean target):
<build>
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
<resources>
<resource>
<directory>${basedir}/target/dependency</directory>
</resource>
</resources>
</build>

I went through every one of these responses looking to make a fat executable JAR file containing all dependencies and none of them worked right. The answer is the shade plugin, it’s very easy and straightforward.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.3</version>
<executions>
<!-- Run shade goal on package phase -->
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>path.to.MainClass</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
Be aware that your dependencies need to have a scope of compile or runtime for this to work properly.
This example came from mkyong.com

Another option if you really want to repackage the other JARs contents inside your single resultant JAR is the Maven Assembly plugin. It unpacks and then repacks everything into a directory via <unpack>true</unpack>. Then you'd have a second pass that built it into one massive JAR.
Another option is the OneJar plugin. This performs the above repackaging actions all in one step.

You could combine the maven-shade-plugin and maven-jar-plugin.
The maven-shade-plugin packs your classes and all dependencies in a single JAR file.
Configure the maven-jar-plugin to specify the main class of your executable JAR file (see Set Up The Classpath, chapter "Make The Jar Executable").
Example POM configuration for maven-jar-plugin:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.example.MyMainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
Finally create the executable JAR file by invoking:
mvn clean package shade:shade

It will work like:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>generate-resources</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
Unpacking has to be in the generate-resources phase or it will not be included as resources.

Ken Liu has it right in my opinion. The Maven dependency plugin allows you to expand all the dependencies, which you can then treat as resources. This allows you to include them in the main artifact. The use of the assembly plugin creates a secondary artifact which can be difficult to modify - in my case I wanted to add custom manifest entries. My POM file ended up as:
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
...
<resources>
<resource>
<directory>${basedir}/target/dependency</directory>
<targetPath>/</targetPath>
</resource>
</resources>
</build>
...
</project>

What is the problem with locating shared assembly files with maven-assembly-plugin-2.2.1?
Try using the descriptorId configuration parameter instead of descriptors/descriptor or descriptorRefs/descriptorRef parameters.
Neither of them do what you need: look for the file on classpath.
Of course you need adding the package where the shared assembly resides on the maven-assembly-plugin's classpath (see below).
If you're using Maven 2.x (not Maven 3.x), you may need adding this dependency in top-most parent pom.xml in the pluginManagement section.
See this for more details.
Class: org.apache.maven.plugin.assembly.io.DefaultAssemblyReader
Example:
<!-- Use the assembly plugin to create a zip file of all our dependencies. -->
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2.1</version>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptorId>assembly-zip-for-wid</descriptorId>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>cz.ness.ct.ip.assemblies</groupId>
<artifactId>TEST_SharedAssemblyDescriptor</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</plugin>

To resolve this issue, we will use the Maven Assembly plugin that will create the JAR file together with its dependency JAR files into a single executable JAR file. Just add the below plugin configuration in your pom.xml file.
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.your.package.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</build>
After doing this, don’t forget to run the Maven tool with this command:
mvn clean compile assembly:single
Maven - Creating a JAR file together with its dependency JAR files into a single executable JAR file

It may not be a good idea to embed all the dependencies in the project's JAR file itself.
I see the point (ease of deployment / usage), but it depends of the use case of your project (and there may be alternatives (see below)).
If you use it fully standalone, why not?
But if you use your project in other contexts (like in a web application, or dropped in a folder where other JARs are sitting), you may have JAR duplicates in your classpath (the ones in the folder, the one in the JAR files). Maybe not a bid deal, but I usually avoid this.
A good alternative:
deploy your application as a ZIP or WAR file: the archive contains your project's JAR file and all dependent JAR files;
use a dynamic classloader mechanism (see Spring Framework, or you can easily do this yourself) to have a single entry point of your project (a single class to start - see the Manifest mechanism in another answer), which will add (dynamically) to the current classpath all the other needed JAR files.
Like this, with in the end just a manifest and a "special dynamic classloader main", you can start your project with:
java -jar ProjectMainJar.jar com.stackoverflow.projectName.MainDynamicClassLoaderClass

I compared the tree plugins mentioned in this post. I generated two JAR files and a directory with all the JAR files. I compared the results and definitely the maven-shade-plugin is the best.
My challenge was that I have multiple Spring resources that needed to be merged, as well as jax-rs, and JDBC services. They were all merged properly by the shade plugin in comparison with the maven-assembly-plugin. In which case Spring will fail unless you copy them to your own resources folder and merge them manually one time.
Both plugins output the correct dependency tree. I had multiple scopes like test, provide, compile, etc. The test and provided were skipped by both plugins. They both produced the same manifest, but I was able to consolidate licenses with the shade plugin using their transformer.
With the maven-dependency-plugin of course you don't have those problems, because the JAR files are not extracted. But like some other have pointed out, you need to carry one extra file(s) to work properly.
Here is a snip of the pom.xml file:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<includeScope>compile</includeScope>
<excludeTransitive>true</excludeTransitive>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.6</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.rbccm.itf.cdd.poller.landingzone.LandingZonePoller</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.4.3</version>
<configuration>
<shadedArtifactAttached>false</shadedArtifactAttached>
<keepDependenciesWithProvidedScope>false</keepDependenciesWithProvidedScope>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/services/javax.ws.rs.ext.Providers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.factories</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.handlers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.schemas</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.tooling</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"/>
<transformer implementation="org.apache.maven.plugins.shade.resource.ApacheLicenseResourceTransformer">
</transformer>
</transformers>
</configuration>
<executions>
<execution>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

For anyone looking for options to exclude specific dependencies from the über JAR file, this is a solution that worked for me:
<project...>
<dependencies>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.11</artifactId>
<version>1.6.1</version>
<scope>provided</scope> <!-- <============= -->
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>...</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
It's not a configuration of the mvn-assembly-plugin, but a property of the dependency.

Something that has worked for me was:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/classes</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>SimpleKeyLogger</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
I had an extraordinary case, because my dependency was system one:
<dependency>
..
<scope>system</scope>
<systemPath>${project.basedir}/lib/myjar.jar</systemPath>
</dependency>
I have changed the code provided by user189057 with changes:
maven-dependency-plugin is executed in "prepare-package" phase
I am extracting unpacked classes directly to "target/classes"

This is the best way I found:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.myDomain.etc.MainClassName</mainClass>
<classpathPrefix>dependency-jars/</classpathPrefix>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.5.1</version>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>
${project.build.directory}/dependency-jars/
</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
With this configuration, all dependencies will be located in /dependency-jars. My application has no Main class, just context ones, but one of my dependencies do have a Main class (com.myDomain.etc.MainClassName) that starts the JMX server, and receives a start or a stop parameter. So with this I was able to start my application like this:
java -jar ./lib/TestApp-1.0-SNAPSHOT.jar start

There are millions of answers already. I wanted to add you don't need <mainClass> if you don't need to add entryPoint to your application. For example, APIs may not have necessarily have a main method.
Maven plugin configuration
<build>
<finalName>log-enrichment</finalName>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
Build
mvn clean compile assembly:single
Verify
ll target/
total 35100
drwxrwx--- 1 root vboxsf 4096 Sep 29 16:25 ./
drwxrwx--- 1 root vboxsf 4096 Sep 29 16:25 ../
drwxrwx--- 1 root vboxsf 0 Sep 29 16:08 archive-tmp/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 classes/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 generated-sources/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 generated-test-sources/
-rwxrwx--- 1 root vboxsf 35929841 Sep 29 16:10 log-enrichment-jar-with-dependencies.jar*
drwxrwx--- 1 root vboxsf 0 Sep 29 16:08 maven-status/

I wanted to migrate my Spring application (using Apereo Foundation's CAS client) to Spring Boot 1.5. I ran into many problems, like:
no main manifest attribute, in target/cas-client-web.jar
I tried to make one unique JAR file with all dependencies. After searching on the Internet, I was able to do it with these lines:
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<fork>true</fork>
<mainClass>${start-class}</mainClass>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>${start-class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
start-class is my main class:
<properties>
<java.version>1.8</java.version>
<start-class>com.test.Application</start-class>
</properties>
And my Application is:
package com.test;
import java.util.Arrays;
import com.test.TestProperties;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
#SpringBootApplication
#EnableAutoConfiguration
#EnableConfigurationProperties({TestProperties.class})
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
return args -> {
System.out.println("Let's inspect the beans provided by Spring Boot:");
String[] beanNames = ctx.getBeanDefinitionNames();
Arrays.sort(beanNames);
for (String beanName : beanNames) {
System.out.println(beanName);
}
};
}
}

To create an executable JAR from the command line itself, just run the below command from the project path:
mvn assembly:assembly

This could also be an option. You will be able to build your JAR file.
<build>
<plugins>
<plugin>
<!-- Build an executable JAR -->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>WordListDriver</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>

I tried the most upvoted answer here and was able to get the JAR file runnable. But the program didn't run correctly. I do not know what the reason was. When I try to run from Eclipse, I get a different result, but when I run the JAR file from command line I get a different result (it crashes with a program-specific runtime error).
I had a similar requirement as the OP just that I had too many (Maven) dependencies for my project. Fortunately, the only solution that worked for me was that using Eclipse. It is very simple and very straightforward. This is not a solution for the OP, but it is a solution for someone who has a similar requirement, but with many Maven dependencies,
Just right-click on your project folder (in Eclipse) and select Export
Then select Java → Runnable JAR
You will be asked to choose the location of the JAR file
Finally, select the class that has the Main method that you want to run and choose *Package dependencies with the JAR file and click Finish

Add to file pom.xml:
<dependency>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
</dependency>
And
<plugin>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
<executions>
<execution>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
That’s it. Next, the mvn package will also create one fat JAR additionally, including all dependency JAR files.

The maven-assembly-plugin worked great for me.
I spent hours with the maven-dependency-plugin and couldn't make it work. The main reason was that I had to define the artifact items explicitly in the configuration section which should be included as it is described in the documentation.
There is an example there for the cases when you want to use it like: mvn dependency:copy, where there are not included any artifactItems, but it doesn't work.

I tried multiple solutions, but this is the one that worked perfectly in the scenario where we wanted to create a non-executable fat JAR file with all internal dependencies for external systems having no previous relevance. A production scenario was tested.
Include this in the pom.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
The command to run to build the fat JAR file:
mvn assembly:assembly

This blog post shows another approach with combining the maven-jar and maven-assembly plugins. With the assembly configuration XML file from the blog post it can also be controlled if dependencies will be expanded or just be collected in a folder and referenced by a classpath entry in the manifest:
The ideal solution is to include the jars in a lib folder and the manifest.mf file of the main jar include all the jars in classpath.
And exactly that one is described here: Executable JAR file with dependent JAR files using Maven

How to create a jar file on Apache NetBeans IDE [duplicate]

I want to package my project in a single executable JAR for distribution.
How can I make a Maven project package all dependency JARs into my output JAR?

<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
and you run it with
mvn clean compile assembly:single
Compile goal should be added before assembly:single or otherwise the code on your own project is not included.
See more details in comments.
Commonly this goal is tied to a build phase to execute automatically. This ensures the JAR is built when executing mvn install or performing a deployment/release.
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>

You can use the dependency-plugin to generate all dependencies in a separate directory before the package phase and then include that in the classpath of the manifest:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>theMainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
Alternatively, use ${project.build.directory}/classes/lib as OutputDirectory to integrate all JAR files into the main JAR file, but then you will need to add custom classloading code to load the JAR files.

See executable-jar-with-maven-example (GitHub)
Notes
Those pros and cons are provided by Stephan.
For Manual Deployment
Pros
Cons
Dependencies are out of the final jar.
Copy Dependencies to a specific directory
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/${project.build.finalName}.lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
Make the JAR File Executable and Classpath Aware
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>${project.build.finalName}.lib/</classpathPrefix>
<mainClass>${fully.qualified.main.class}</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
At this point the JAR file is actually executable with external classpath elements.
java -jar target/${project.build.finalName}.jar
Make Deployable Archives
The JAR file is only executable with the sibling ...lib/ directory. We need to make archives to deploy with the directory and its content.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<id>antrun-archive</id>
<phase>package</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<target>
<property name="final.name" value="${project.build.directory}/${project.build.finalName}"/>
<property name="archive.includes" value="${project.build.finalName}.${project.packaging} ${project.build.finalName}.lib/*"/>
<property name="tar.destfile" value="${final.name}.tar"/>
<zip basedir="${project.build.directory}" destfile="${final.name}.zip" includes="${archive.includes}" />
<tar basedir="${project.build.directory}" destfile="${tar.destfile}" includes="${archive.includes}" />
<gzip src="${tar.destfile}" destfile="${tar.destfile}.gz" />
<bzip2 src="${tar.destfile}" destfile="${tar.destfile}.bz2" />
</target>
</configuration>
</execution>
</executions>
</plugin>
Now you have target/${project.build.finalName}.(zip|tar|tar.bz2|tar.gz) which each contains the jar and lib/*.
Apache Maven Assembly Plugin
Pros
Cons
No class relocation support (use maven-shade-plugin if class relocation is needed).
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<archive>
<manifest>
<mainClass>${fully.qualified.main.class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.bulid.finalName}-jar-with-dependencies.jar.
Apache Maven Shade Plugin
Pros
Cons
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<shadedArtifactAttached>true</shadedArtifactAttached>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>${fully.qualified.main.class}</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.build.finalName}-shaded.jar.
onejar-maven-plugin
Pros
Cons
Not actively supported since 2012.
<plugin>
<!--groupId>org.dstovall</groupId--> <!-- not available on the central -->
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<executions>
<execution>
<configuration>
<mainClass>${fully.qualified.main.class}</mainClass>
<attachToBuild>true</attachToBuild>
<!-- https://code.google.com/p/onejar-maven-plugin/issues/detail?id=8 -->
<!-- classifier>onejar</classifier -->
<filename>${project.build.finalName}-onejar.${project.packaging}</filename>
</configuration>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
Spring Boot Maven Plugin
Pros
Cons
Add potential unnecessary Spring and Spring Boot related classes.
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
<configuration>
<classifier>spring-boot</classifier>
<mainClass>${fully.qualified.main.class}</mainClass>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.bulid.finalName}-spring-boot.jar.

Taking IAdapter's answer and reformatting it, we have:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
Next, I would recommend making this a natural part of your build, rather than something to call explicitly. To make this a integral part of your build, add this plugin to your pom.xml and bind it to the package lifecycle event. However, a gotcha is that you need to call the assembly:single goal if putting this in your pom.xml, while you would call 'assembly:assembly' if executing it manually from the command line.
<project>
[...]
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
[...]
</plugins>
[...]
</build>
</project>

Use the maven-shade-plugin to package all dependencies into one über-JAR file. It can also be used to build an executable JAR file by specifying the main class. After trying to use maven-assembly and maven-jar, I found that this plugin best suited my needs.
I found this plugin particularly useful as it merges the content of specific files instead of overwriting them. This is needed when there are resource files that are have the same name across the JAR files and the plugin tries to package all the resource files.
See the example below:
<plugins>
<!-- This plugin provides the capability to package
the artifact in an über-JAR file, including
its dependencies and to shade - i.e. rename -
the packages of some of the dependencies. -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.4</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<artifactSet>
<!-- Signed JAR files-->
<excludes>
<exclude>bouncycastle:bcprov-jdk15</exclude>
</excludes>
</artifactSet>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<!-- Main class -->
<mainClass>com.main.MyMainClass</mainClass>
</transformer>
<!-- Use resource transformers to prevent file overwrites -->
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>properties.properties</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.XmlAppendingTransformer">
<resource>applicationContext.xml</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/cxf/cxf.extension</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.XmlAppendingTransformer">
<resource>META-INF/cxf/bus-extensions.xml</resource>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>

You can use the maven-shade plugin to build an über JAR file like below:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

I have long used the Maven assembly plugin, but I could not find a solution to the problem with "already added, skipping". Now, I'm using another plugin - onejar-maven-plugin. An example is below (mvn package builds the JAR file):
<plugin>
<groupId>org.dstovall</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.3.0</version>
<executions>
<execution>
<configuration>
<mainClass>com.company.MainClass</mainClass>
</configuration>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
You need to add a repository for that plugin:
<pluginRepositories>
<pluginRepository>
<id>onejar-maven-plugin.googlecode.com</id>
<url>http://onejar-maven-plugin.googlecode.com/svn/mavenrepo</url>
</pluginRepository>
</pluginRepositories>

You can add the following to your pom.xml file:
<build>
<defaultGoal>install</defaultGoal>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.1</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.mycompany.package.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>com.mycompany.package.MainClass</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Afterwards you have to switch via the console to the directory, where the pom.xml file is located. Then you have to execute mvn assembly:single and then your executable JAR file with dependencies will be hopefully build. You can check it when switching to the output (target) directory with cd ./target and starting your JAR with a command similar to java -jar mavenproject1-1.0-SNAPSHOT-jar-with-dependencies.jar.
I tested this with Apache Maven 3.0.3.

You can use maven-dependency-plugin, but the question was how to create an executable JAR file. To do that requires the following alteration to Matthew Franglen's response (btw, using the dependency plugin takes longer to build when starting from a clean target):
<build>
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
<resources>
<resource>
<directory>${basedir}/target/dependency</directory>
</resource>
</resources>
</build>

I went through every one of these responses looking to make a fat executable JAR file containing all dependencies and none of them worked right. The answer is the shade plugin, it’s very easy and straightforward.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.3</version>
<executions>
<!-- Run shade goal on package phase -->
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>path.to.MainClass</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
Be aware that your dependencies need to have a scope of compile or runtime for this to work properly.
This example came from mkyong.com

Another option if you really want to repackage the other JARs contents inside your single resultant JAR is the Maven Assembly plugin. It unpacks and then repacks everything into a directory via <unpack>true</unpack>. Then you'd have a second pass that built it into one massive JAR.
Another option is the OneJar plugin. This performs the above repackaging actions all in one step.

You could combine the maven-shade-plugin and maven-jar-plugin.
The maven-shade-plugin packs your classes and all dependencies in a single JAR file.
Configure the maven-jar-plugin to specify the main class of your executable JAR file (see Set Up The Classpath, chapter "Make The Jar Executable").
Example POM configuration for maven-jar-plugin:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.example.MyMainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
Finally create the executable JAR file by invoking:
mvn clean package shade:shade

It will work like:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>generate-resources</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
Unpacking has to be in the generate-resources phase or it will not be included as resources.

Ken Liu has it right in my opinion. The Maven dependency plugin allows you to expand all the dependencies, which you can then treat as resources. This allows you to include them in the main artifact. The use of the assembly plugin creates a secondary artifact which can be difficult to modify - in my case I wanted to add custom manifest entries. My POM file ended up as:
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
...
<resources>
<resource>
<directory>${basedir}/target/dependency</directory>
<targetPath>/</targetPath>
</resource>
</resources>
</build>
...
</project>

What is the problem with locating shared assembly files with maven-assembly-plugin-2.2.1?
Try using the descriptorId configuration parameter instead of descriptors/descriptor or descriptorRefs/descriptorRef parameters.
Neither of them do what you need: look for the file on classpath.
Of course you need adding the package where the shared assembly resides on the maven-assembly-plugin's classpath (see below).
If you're using Maven 2.x (not Maven 3.x), you may need adding this dependency in top-most parent pom.xml in the pluginManagement section.
See this for more details.
Class: org.apache.maven.plugin.assembly.io.DefaultAssemblyReader
Example:
<!-- Use the assembly plugin to create a zip file of all our dependencies. -->
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2.1</version>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptorId>assembly-zip-for-wid</descriptorId>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>cz.ness.ct.ip.assemblies</groupId>
<artifactId>TEST_SharedAssemblyDescriptor</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</plugin>

To resolve this issue, we will use the Maven Assembly plugin that will create the JAR file together with its dependency JAR files into a single executable JAR file. Just add the below plugin configuration in your pom.xml file.
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.your.package.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</build>
After doing this, don’t forget to run the Maven tool with this command:
mvn clean compile assembly:single
Maven - Creating a JAR file together with its dependency JAR files into a single executable JAR file

It may not be a good idea to embed all the dependencies in the project's JAR file itself.
I see the point (ease of deployment / usage), but it depends of the use case of your project (and there may be alternatives (see below)).
If you use it fully standalone, why not?
But if you use your project in other contexts (like in a web application, or dropped in a folder where other JARs are sitting), you may have JAR duplicates in your classpath (the ones in the folder, the one in the JAR files). Maybe not a bid deal, but I usually avoid this.
A good alternative:
deploy your application as a ZIP or WAR file: the archive contains your project's JAR file and all dependent JAR files;
use a dynamic classloader mechanism (see Spring Framework, or you can easily do this yourself) to have a single entry point of your project (a single class to start - see the Manifest mechanism in another answer), which will add (dynamically) to the current classpath all the other needed JAR files.
Like this, with in the end just a manifest and a "special dynamic classloader main", you can start your project with:
java -jar ProjectMainJar.jar com.stackoverflow.projectName.MainDynamicClassLoaderClass

I compared the tree plugins mentioned in this post. I generated two JAR files and a directory with all the JAR files. I compared the results and definitely the maven-shade-plugin is the best.
My challenge was that I have multiple Spring resources that needed to be merged, as well as jax-rs, and JDBC services. They were all merged properly by the shade plugin in comparison with the maven-assembly-plugin. In which case Spring will fail unless you copy them to your own resources folder and merge them manually one time.
Both plugins output the correct dependency tree. I had multiple scopes like test, provide, compile, etc. The test and provided were skipped by both plugins. They both produced the same manifest, but I was able to consolidate licenses with the shade plugin using their transformer.
With the maven-dependency-plugin of course you don't have those problems, because the JAR files are not extracted. But like some other have pointed out, you need to carry one extra file(s) to work properly.
Here is a snip of the pom.xml file:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<includeScope>compile</includeScope>
<excludeTransitive>true</excludeTransitive>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.6</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.rbccm.itf.cdd.poller.landingzone.LandingZonePoller</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.4.3</version>
<configuration>
<shadedArtifactAttached>false</shadedArtifactAttached>
<keepDependenciesWithProvidedScope>false</keepDependenciesWithProvidedScope>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/services/javax.ws.rs.ext.Providers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.factories</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.handlers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.schemas</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.tooling</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"/>
<transformer implementation="org.apache.maven.plugins.shade.resource.ApacheLicenseResourceTransformer">
</transformer>
</transformers>
</configuration>
<executions>
<execution>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

For anyone looking for options to exclude specific dependencies from the über JAR file, this is a solution that worked for me:
<project...>
<dependencies>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.11</artifactId>
<version>1.6.1</version>
<scope>provided</scope> <!-- <============= -->
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>...</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
It's not a configuration of the mvn-assembly-plugin, but a property of the dependency.

Something that has worked for me was:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/classes</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>SimpleKeyLogger</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
I had an extraordinary case, because my dependency was system one:
<dependency>
..
<scope>system</scope>
<systemPath>${project.basedir}/lib/myjar.jar</systemPath>
</dependency>
I have changed the code provided by user189057 with changes:
maven-dependency-plugin is executed in "prepare-package" phase
I am extracting unpacked classes directly to "target/classes"

This is the best way I found:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.myDomain.etc.MainClassName</mainClass>
<classpathPrefix>dependency-jars/</classpathPrefix>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.5.1</version>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>
${project.build.directory}/dependency-jars/
</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
With this configuration, all dependencies will be located in /dependency-jars. My application has no Main class, just context ones, but one of my dependencies do have a Main class (com.myDomain.etc.MainClassName) that starts the JMX server, and receives a start or a stop parameter. So with this I was able to start my application like this:
java -jar ./lib/TestApp-1.0-SNAPSHOT.jar start

There are millions of answers already. I wanted to add you don't need <mainClass> if you don't need to add entryPoint to your application. For example, APIs may not have necessarily have a main method.
Maven plugin configuration
<build>
<finalName>log-enrichment</finalName>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
Build
mvn clean compile assembly:single
Verify
ll target/
total 35100
drwxrwx--- 1 root vboxsf 4096 Sep 29 16:25 ./
drwxrwx--- 1 root vboxsf 4096 Sep 29 16:25 ../
drwxrwx--- 1 root vboxsf 0 Sep 29 16:08 archive-tmp/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 classes/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 generated-sources/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 generated-test-sources/
-rwxrwx--- 1 root vboxsf 35929841 Sep 29 16:10 log-enrichment-jar-with-dependencies.jar*
drwxrwx--- 1 root vboxsf 0 Sep 29 16:08 maven-status/

I wanted to migrate my Spring application (using Apereo Foundation's CAS client) to Spring Boot 1.5. I ran into many problems, like:
no main manifest attribute, in target/cas-client-web.jar
I tried to make one unique JAR file with all dependencies. After searching on the Internet, I was able to do it with these lines:
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<fork>true</fork>
<mainClass>${start-class}</mainClass>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>${start-class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
start-class is my main class:
<properties>
<java.version>1.8</java.version>
<start-class>com.test.Application</start-class>
</properties>
And my Application is:
package com.test;
import java.util.Arrays;
import com.test.TestProperties;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
#SpringBootApplication
#EnableAutoConfiguration
#EnableConfigurationProperties({TestProperties.class})
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
return args -> {
System.out.println("Let's inspect the beans provided by Spring Boot:");
String[] beanNames = ctx.getBeanDefinitionNames();
Arrays.sort(beanNames);
for (String beanName : beanNames) {
System.out.println(beanName);
}
};
}
}

To create an executable JAR from the command line itself, just run the below command from the project path:
mvn assembly:assembly

This could also be an option. You will be able to build your JAR file.
<build>
<plugins>
<plugin>
<!-- Build an executable JAR -->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>WordListDriver</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>

I tried the most upvoted answer here and was able to get the JAR file runnable. But the program didn't run correctly. I do not know what the reason was. When I try to run from Eclipse, I get a different result, but when I run the JAR file from command line I get a different result (it crashes with a program-specific runtime error).
I had a similar requirement as the OP just that I had too many (Maven) dependencies for my project. Fortunately, the only solution that worked for me was that using Eclipse. It is very simple and very straightforward. This is not a solution for the OP, but it is a solution for someone who has a similar requirement, but with many Maven dependencies,
Just right-click on your project folder (in Eclipse) and select Export
Then select Java → Runnable JAR
You will be asked to choose the location of the JAR file
Finally, select the class that has the Main method that you want to run and choose *Package dependencies with the JAR file and click Finish

Add to file pom.xml:
<dependency>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
</dependency>
And
<plugin>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
<executions>
<execution>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
That’s it. Next, the mvn package will also create one fat JAR additionally, including all dependency JAR files.

The maven-assembly-plugin worked great for me.
I spent hours with the maven-dependency-plugin and couldn't make it work. The main reason was that I had to define the artifact items explicitly in the configuration section which should be included as it is described in the documentation.
There is an example there for the cases when you want to use it like: mvn dependency:copy, where there are not included any artifactItems, but it doesn't work.

I tried multiple solutions, but this is the one that worked perfectly in the scenario where we wanted to create a non-executable fat JAR file with all internal dependencies for external systems having no previous relevance. A production scenario was tested.
Include this in the pom.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
The command to run to build the fat JAR file:
mvn assembly:assembly

This blog post shows another approach with combining the maven-jar and maven-assembly plugins. With the assembly configuration XML file from the blog post it can also be controlled if dependencies will be expanded or just be collected in a folder and referenced by a classpath entry in the manifest:
The ideal solution is to include the jars in a lib folder and the manifest.mf file of the main jar include all the jars in classpath.
And exactly that one is described here: Executable JAR file with dependent JAR files using Maven

How to run a Java Maven project from terminal [duplicate]

I want to package my project in a single executable JAR for distribution.
How can I make a Maven project package all dependency JARs into my output JAR?

<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
and you run it with
mvn clean compile assembly:single
Compile goal should be added before assembly:single or otherwise the code on your own project is not included.
See more details in comments.
Commonly this goal is tied to a build phase to execute automatically. This ensures the JAR is built when executing mvn install or performing a deployment/release.
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>

You can use the dependency-plugin to generate all dependencies in a separate directory before the package phase and then include that in the classpath of the manifest:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>theMainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
Alternatively, use ${project.build.directory}/classes/lib as OutputDirectory to integrate all JAR files into the main JAR file, but then you will need to add custom classloading code to load the JAR files.

See executable-jar-with-maven-example (GitHub)
Notes
Those pros and cons are provided by Stephan.
For Manual Deployment
Pros
Cons
Dependencies are out of the final jar.
Copy Dependencies to a specific directory
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/${project.build.finalName}.lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
Make the JAR File Executable and Classpath Aware
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>${project.build.finalName}.lib/</classpathPrefix>
<mainClass>${fully.qualified.main.class}</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
At this point the JAR file is actually executable with external classpath elements.
java -jar target/${project.build.finalName}.jar
Make Deployable Archives
The JAR file is only executable with the sibling ...lib/ directory. We need to make archives to deploy with the directory and its content.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<id>antrun-archive</id>
<phase>package</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<target>
<property name="final.name" value="${project.build.directory}/${project.build.finalName}"/>
<property name="archive.includes" value="${project.build.finalName}.${project.packaging} ${project.build.finalName}.lib/*"/>
<property name="tar.destfile" value="${final.name}.tar"/>
<zip basedir="${project.build.directory}" destfile="${final.name}.zip" includes="${archive.includes}" />
<tar basedir="${project.build.directory}" destfile="${tar.destfile}" includes="${archive.includes}" />
<gzip src="${tar.destfile}" destfile="${tar.destfile}.gz" />
<bzip2 src="${tar.destfile}" destfile="${tar.destfile}.bz2" />
</target>
</configuration>
</execution>
</executions>
</plugin>
Now you have target/${project.build.finalName}.(zip|tar|tar.bz2|tar.gz) which each contains the jar and lib/*.
Apache Maven Assembly Plugin
Pros
Cons
No class relocation support (use maven-shade-plugin if class relocation is needed).
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<archive>
<manifest>
<mainClass>${fully.qualified.main.class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.bulid.finalName}-jar-with-dependencies.jar.
Apache Maven Shade Plugin
Pros
Cons
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<shadedArtifactAttached>true</shadedArtifactAttached>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>${fully.qualified.main.class}</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.build.finalName}-shaded.jar.
onejar-maven-plugin
Pros
Cons
Not actively supported since 2012.
<plugin>
<!--groupId>org.dstovall</groupId--> <!-- not available on the central -->
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<executions>
<execution>
<configuration>
<mainClass>${fully.qualified.main.class}</mainClass>
<attachToBuild>true</attachToBuild>
<!-- https://code.google.com/p/onejar-maven-plugin/issues/detail?id=8 -->
<!-- classifier>onejar</classifier -->
<filename>${project.build.finalName}-onejar.${project.packaging}</filename>
</configuration>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
Spring Boot Maven Plugin
Pros
Cons
Add potential unnecessary Spring and Spring Boot related classes.
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
<configuration>
<classifier>spring-boot</classifier>
<mainClass>${fully.qualified.main.class}</mainClass>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.bulid.finalName}-spring-boot.jar.

Taking IAdapter's answer and reformatting it, we have:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
Next, I would recommend making this a natural part of your build, rather than something to call explicitly. To make this a integral part of your build, add this plugin to your pom.xml and bind it to the package lifecycle event. However, a gotcha is that you need to call the assembly:single goal if putting this in your pom.xml, while you would call 'assembly:assembly' if executing it manually from the command line.
<project>
[...]
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
[...]
</plugins>
[...]
</build>
</project>

Use the maven-shade-plugin to package all dependencies into one über-JAR file. It can also be used to build an executable JAR file by specifying the main class. After trying to use maven-assembly and maven-jar, I found that this plugin best suited my needs.
I found this plugin particularly useful as it merges the content of specific files instead of overwriting them. This is needed when there are resource files that are have the same name across the JAR files and the plugin tries to package all the resource files.
See the example below:
<plugins>
<!-- This plugin provides the capability to package
the artifact in an über-JAR file, including
its dependencies and to shade - i.e. rename -
the packages of some of the dependencies. -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.4</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<artifactSet>
<!-- Signed JAR files-->
<excludes>
<exclude>bouncycastle:bcprov-jdk15</exclude>
</excludes>
</artifactSet>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<!-- Main class -->
<mainClass>com.main.MyMainClass</mainClass>
</transformer>
<!-- Use resource transformers to prevent file overwrites -->
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>properties.properties</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.XmlAppendingTransformer">
<resource>applicationContext.xml</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/cxf/cxf.extension</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.XmlAppendingTransformer">
<resource>META-INF/cxf/bus-extensions.xml</resource>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>

You can use the maven-shade plugin to build an über JAR file like below:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

I have long used the Maven assembly plugin, but I could not find a solution to the problem with "already added, skipping". Now, I'm using another plugin - onejar-maven-plugin. An example is below (mvn package builds the JAR file):
<plugin>
<groupId>org.dstovall</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.3.0</version>
<executions>
<execution>
<configuration>
<mainClass>com.company.MainClass</mainClass>
</configuration>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
You need to add a repository for that plugin:
<pluginRepositories>
<pluginRepository>
<id>onejar-maven-plugin.googlecode.com</id>
<url>http://onejar-maven-plugin.googlecode.com/svn/mavenrepo</url>
</pluginRepository>
</pluginRepositories>

You can add the following to your pom.xml file:
<build>
<defaultGoal>install</defaultGoal>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.1</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.mycompany.package.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>com.mycompany.package.MainClass</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Afterwards you have to switch via the console to the directory, where the pom.xml file is located. Then you have to execute mvn assembly:single and then your executable JAR file with dependencies will be hopefully build. You can check it when switching to the output (target) directory with cd ./target and starting your JAR with a command similar to java -jar mavenproject1-1.0-SNAPSHOT-jar-with-dependencies.jar.
I tested this with Apache Maven 3.0.3.

You can use maven-dependency-plugin, but the question was how to create an executable JAR file. To do that requires the following alteration to Matthew Franglen's response (btw, using the dependency plugin takes longer to build when starting from a clean target):
<build>
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
<resources>
<resource>
<directory>${basedir}/target/dependency</directory>
</resource>
</resources>
</build>

I went through every one of these responses looking to make a fat executable JAR file containing all dependencies and none of them worked right. The answer is the shade plugin, it’s very easy and straightforward.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.3</version>
<executions>
<!-- Run shade goal on package phase -->
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>path.to.MainClass</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
Be aware that your dependencies need to have a scope of compile or runtime for this to work properly.
This example came from mkyong.com

Another option if you really want to repackage the other JARs contents inside your single resultant JAR is the Maven Assembly plugin. It unpacks and then repacks everything into a directory via <unpack>true</unpack>. Then you'd have a second pass that built it into one massive JAR.
Another option is the OneJar plugin. This performs the above repackaging actions all in one step.

You could combine the maven-shade-plugin and maven-jar-plugin.
The maven-shade-plugin packs your classes and all dependencies in a single JAR file.
Configure the maven-jar-plugin to specify the main class of your executable JAR file (see Set Up The Classpath, chapter "Make The Jar Executable").
Example POM configuration for maven-jar-plugin:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.example.MyMainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
Finally create the executable JAR file by invoking:
mvn clean package shade:shade

It will work like:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>generate-resources</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
Unpacking has to be in the generate-resources phase or it will not be included as resources.

Ken Liu has it right in my opinion. The Maven dependency plugin allows you to expand all the dependencies, which you can then treat as resources. This allows you to include them in the main artifact. The use of the assembly plugin creates a secondary artifact which can be difficult to modify - in my case I wanted to add custom manifest entries. My POM file ended up as:
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
...
<resources>
<resource>
<directory>${basedir}/target/dependency</directory>
<targetPath>/</targetPath>
</resource>
</resources>
</build>
...
</project>

What is the problem with locating shared assembly files with maven-assembly-plugin-2.2.1?
Try using the descriptorId configuration parameter instead of descriptors/descriptor or descriptorRefs/descriptorRef parameters.
Neither of them do what you need: look for the file on classpath.
Of course you need adding the package where the shared assembly resides on the maven-assembly-plugin's classpath (see below).
If you're using Maven 2.x (not Maven 3.x), you may need adding this dependency in top-most parent pom.xml in the pluginManagement section.
See this for more details.
Class: org.apache.maven.plugin.assembly.io.DefaultAssemblyReader
Example:
<!-- Use the assembly plugin to create a zip file of all our dependencies. -->
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2.1</version>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptorId>assembly-zip-for-wid</descriptorId>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>cz.ness.ct.ip.assemblies</groupId>
<artifactId>TEST_SharedAssemblyDescriptor</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</plugin>

To resolve this issue, we will use the Maven Assembly plugin that will create the JAR file together with its dependency JAR files into a single executable JAR file. Just add the below plugin configuration in your pom.xml file.
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.your.package.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</build>
After doing this, don’t forget to run the Maven tool with this command:
mvn clean compile assembly:single
Maven - Creating a JAR file together with its dependency JAR files into a single executable JAR file

It may not be a good idea to embed all the dependencies in the project's JAR file itself.
I see the point (ease of deployment / usage), but it depends of the use case of your project (and there may be alternatives (see below)).
If you use it fully standalone, why not?
But if you use your project in other contexts (like in a web application, or dropped in a folder where other JARs are sitting), you may have JAR duplicates in your classpath (the ones in the folder, the one in the JAR files). Maybe not a bid deal, but I usually avoid this.
A good alternative:
deploy your application as a ZIP or WAR file: the archive contains your project's JAR file and all dependent JAR files;
use a dynamic classloader mechanism (see Spring Framework, or you can easily do this yourself) to have a single entry point of your project (a single class to start - see the Manifest mechanism in another answer), which will add (dynamically) to the current classpath all the other needed JAR files.
Like this, with in the end just a manifest and a "special dynamic classloader main", you can start your project with:
java -jar ProjectMainJar.jar com.stackoverflow.projectName.MainDynamicClassLoaderClass

I compared the tree plugins mentioned in this post. I generated two JAR files and a directory with all the JAR files. I compared the results and definitely the maven-shade-plugin is the best.
My challenge was that I have multiple Spring resources that needed to be merged, as well as jax-rs, and JDBC services. They were all merged properly by the shade plugin in comparison with the maven-assembly-plugin. In which case Spring will fail unless you copy them to your own resources folder and merge them manually one time.
Both plugins output the correct dependency tree. I had multiple scopes like test, provide, compile, etc. The test and provided were skipped by both plugins. They both produced the same manifest, but I was able to consolidate licenses with the shade plugin using their transformer.
With the maven-dependency-plugin of course you don't have those problems, because the JAR files are not extracted. But like some other have pointed out, you need to carry one extra file(s) to work properly.
Here is a snip of the pom.xml file:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<includeScope>compile</includeScope>
<excludeTransitive>true</excludeTransitive>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.6</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.rbccm.itf.cdd.poller.landingzone.LandingZonePoller</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.4.3</version>
<configuration>
<shadedArtifactAttached>false</shadedArtifactAttached>
<keepDependenciesWithProvidedScope>false</keepDependenciesWithProvidedScope>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/services/javax.ws.rs.ext.Providers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.factories</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.handlers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.schemas</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.tooling</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"/>
<transformer implementation="org.apache.maven.plugins.shade.resource.ApacheLicenseResourceTransformer">
</transformer>
</transformers>
</configuration>
<executions>
<execution>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

For anyone looking for options to exclude specific dependencies from the über JAR file, this is a solution that worked for me:
<project...>
<dependencies>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.11</artifactId>
<version>1.6.1</version>
<scope>provided</scope> <!-- <============= -->
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>...</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
It's not a configuration of the mvn-assembly-plugin, but a property of the dependency.

Something that has worked for me was:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/classes</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>SimpleKeyLogger</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
I had an extraordinary case, because my dependency was system one:
<dependency>
..
<scope>system</scope>
<systemPath>${project.basedir}/lib/myjar.jar</systemPath>
</dependency>
I have changed the code provided by user189057 with changes:
maven-dependency-plugin is executed in "prepare-package" phase
I am extracting unpacked classes directly to "target/classes"

This is the best way I found:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.myDomain.etc.MainClassName</mainClass>
<classpathPrefix>dependency-jars/</classpathPrefix>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.5.1</version>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>
${project.build.directory}/dependency-jars/
</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
With this configuration, all dependencies will be located in /dependency-jars. My application has no Main class, just context ones, but one of my dependencies do have a Main class (com.myDomain.etc.MainClassName) that starts the JMX server, and receives a start or a stop parameter. So with this I was able to start my application like this:
java -jar ./lib/TestApp-1.0-SNAPSHOT.jar start

There are millions of answers already. I wanted to add you don't need <mainClass> if you don't need to add entryPoint to your application. For example, APIs may not have necessarily have a main method.
Maven plugin configuration
<build>
<finalName>log-enrichment</finalName>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
Build
mvn clean compile assembly:single
Verify
ll target/
total 35100
drwxrwx--- 1 root vboxsf 4096 Sep 29 16:25 ./
drwxrwx--- 1 root vboxsf 4096 Sep 29 16:25 ../
drwxrwx--- 1 root vboxsf 0 Sep 29 16:08 archive-tmp/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 classes/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 generated-sources/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 generated-test-sources/
-rwxrwx--- 1 root vboxsf 35929841 Sep 29 16:10 log-enrichment-jar-with-dependencies.jar*
drwxrwx--- 1 root vboxsf 0 Sep 29 16:08 maven-status/

I wanted to migrate my Spring application (using Apereo Foundation's CAS client) to Spring Boot 1.5. I ran into many problems, like:
no main manifest attribute, in target/cas-client-web.jar
I tried to make one unique JAR file with all dependencies. After searching on the Internet, I was able to do it with these lines:
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<fork>true</fork>
<mainClass>${start-class}</mainClass>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>${start-class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
start-class is my main class:
<properties>
<java.version>1.8</java.version>
<start-class>com.test.Application</start-class>
</properties>
And my Application is:
package com.test;
import java.util.Arrays;
import com.test.TestProperties;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
#SpringBootApplication
#EnableAutoConfiguration
#EnableConfigurationProperties({TestProperties.class})
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
return args -> {
System.out.println("Let's inspect the beans provided by Spring Boot:");
String[] beanNames = ctx.getBeanDefinitionNames();
Arrays.sort(beanNames);
for (String beanName : beanNames) {
System.out.println(beanName);
}
};
}
}

To create an executable JAR from the command line itself, just run the below command from the project path:
mvn assembly:assembly

This could also be an option. You will be able to build your JAR file.
<build>
<plugins>
<plugin>
<!-- Build an executable JAR -->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>WordListDriver</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>

I tried the most upvoted answer here and was able to get the JAR file runnable. But the program didn't run correctly. I do not know what the reason was. When I try to run from Eclipse, I get a different result, but when I run the JAR file from command line I get a different result (it crashes with a program-specific runtime error).
I had a similar requirement as the OP just that I had too many (Maven) dependencies for my project. Fortunately, the only solution that worked for me was that using Eclipse. It is very simple and very straightforward. This is not a solution for the OP, but it is a solution for someone who has a similar requirement, but with many Maven dependencies,
Just right-click on your project folder (in Eclipse) and select Export
Then select Java → Runnable JAR
You will be asked to choose the location of the JAR file
Finally, select the class that has the Main method that you want to run and choose *Package dependencies with the JAR file and click Finish

Add to file pom.xml:
<dependency>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
</dependency>
And
<plugin>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
<executions>
<execution>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
That’s it. Next, the mvn package will also create one fat JAR additionally, including all dependency JAR files.

The maven-assembly-plugin worked great for me.
I spent hours with the maven-dependency-plugin and couldn't make it work. The main reason was that I had to define the artifact items explicitly in the configuration section which should be included as it is described in the documentation.
There is an example there for the cases when you want to use it like: mvn dependency:copy, where there are not included any artifactItems, but it doesn't work.

I tried multiple solutions, but this is the one that worked perfectly in the scenario where we wanted to create a non-executable fat JAR file with all internal dependencies for external systems having no previous relevance. A production scenario was tested.
Include this in the pom.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
The command to run to build the fat JAR file:
mvn assembly:assembly

This blog post shows another approach with combining the maven-jar and maven-assembly plugins. With the assembly configuration XML file from the blog post it can also be controlled if dependencies will be expanded or just be collected in a folder and referenced by a classpath entry in the manifest:
The ideal solution is to include the jars in a lib folder and the manifest.mf file of the main jar include all the jars in classpath.
And exactly that one is described here: Executable JAR file with dependent JAR files using Maven

Maven assembly plugin creates two unexpected jars

I want to use maven-assembly-plugin to pack external dependencies into the application's jar file. When I call mvn install it creates two jar files, one with and one without the dependencies. (appname-version.jar and appname-version-jar-with-dependencies.jar)
My question is that why it creates two jar files?
Here is the plugin: (im not using any other plugin at the moment)
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>com.coolapp.mainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
Thank you!

You need to define the maven-jar-plugin to avoid creating the default jar. This is done by adding <phase>none</phase> under execution:
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
<executions>
<execution>
<id>default-jar</id>
<phase>none</phase>
</execution>
</executions>
</plugin>
All the resources/classes are still moved to the target folder, so maven-assembly can still execute itself correctly.

Maven - why the built JAR can't find a jar that's in its lib folder? [duplicate]

I want to package my project in a single executable JAR for distribution.
How can I make a Maven project package all dependency JARs into my output JAR?

<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
and you run it with
mvn clean compile assembly:single
Compile goal should be added before assembly:single or otherwise the code on your own project is not included.
See more details in comments.
Commonly this goal is tied to a build phase to execute automatically. This ensures the JAR is built when executing mvn install or performing a deployment/release.
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>

You can use the dependency-plugin to generate all dependencies in a separate directory before the package phase and then include that in the classpath of the manifest:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>theMainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
Alternatively, use ${project.build.directory}/classes/lib as OutputDirectory to integrate all JAR files into the main JAR file, but then you will need to add custom classloading code to load the JAR files.

See executable-jar-with-maven-example (GitHub)
Notes
Those pros and cons are provided by Stephan.
For Manual Deployment
Pros
Cons
Dependencies are out of the final jar.
Copy Dependencies to a specific directory
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/${project.build.finalName}.lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
Make the JAR File Executable and Classpath Aware
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>${project.build.finalName}.lib/</classpathPrefix>
<mainClass>${fully.qualified.main.class}</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
At this point the JAR file is actually executable with external classpath elements.
java -jar target/${project.build.finalName}.jar
Make Deployable Archives
The JAR file is only executable with the sibling ...lib/ directory. We need to make archives to deploy with the directory and its content.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<id>antrun-archive</id>
<phase>package</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<target>
<property name="final.name" value="${project.build.directory}/${project.build.finalName}"/>
<property name="archive.includes" value="${project.build.finalName}.${project.packaging} ${project.build.finalName}.lib/*"/>
<property name="tar.destfile" value="${final.name}.tar"/>
<zip basedir="${project.build.directory}" destfile="${final.name}.zip" includes="${archive.includes}" />
<tar basedir="${project.build.directory}" destfile="${tar.destfile}" includes="${archive.includes}" />
<gzip src="${tar.destfile}" destfile="${tar.destfile}.gz" />
<bzip2 src="${tar.destfile}" destfile="${tar.destfile}.bz2" />
</target>
</configuration>
</execution>
</executions>
</plugin>
Now you have target/${project.build.finalName}.(zip|tar|tar.bz2|tar.gz) which each contains the jar and lib/*.
Apache Maven Assembly Plugin
Pros
Cons
No class relocation support (use maven-shade-plugin if class relocation is needed).
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<archive>
<manifest>
<mainClass>${fully.qualified.main.class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.bulid.finalName}-jar-with-dependencies.jar.
Apache Maven Shade Plugin
Pros
Cons
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<shadedArtifactAttached>true</shadedArtifactAttached>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>${fully.qualified.main.class}</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.build.finalName}-shaded.jar.
onejar-maven-plugin
Pros
Cons
Not actively supported since 2012.
<plugin>
<!--groupId>org.dstovall</groupId--> <!-- not available on the central -->
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<executions>
<execution>
<configuration>
<mainClass>${fully.qualified.main.class}</mainClass>
<attachToBuild>true</attachToBuild>
<!-- https://code.google.com/p/onejar-maven-plugin/issues/detail?id=8 -->
<!-- classifier>onejar</classifier -->
<filename>${project.build.finalName}-onejar.${project.packaging}</filename>
</configuration>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
Spring Boot Maven Plugin
Pros
Cons
Add potential unnecessary Spring and Spring Boot related classes.
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
<configuration>
<classifier>spring-boot</classifier>
<mainClass>${fully.qualified.main.class}</mainClass>
</configuration>
</execution>
</executions>
</plugin>
You have target/${project.bulid.finalName}-spring-boot.jar.

Taking IAdapter's answer and reformatting it, we have:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
Next, I would recommend making this a natural part of your build, rather than something to call explicitly. To make this a integral part of your build, add this plugin to your pom.xml and bind it to the package lifecycle event. However, a gotcha is that you need to call the assembly:single goal if putting this in your pom.xml, while you would call 'assembly:assembly' if executing it manually from the command line.
<project>
[...]
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
[...]
</plugins>
[...]
</build>
</project>

Use the maven-shade-plugin to package all dependencies into one über-JAR file. It can also be used to build an executable JAR file by specifying the main class. After trying to use maven-assembly and maven-jar, I found that this plugin best suited my needs.
I found this plugin particularly useful as it merges the content of specific files instead of overwriting them. This is needed when there are resource files that are have the same name across the JAR files and the plugin tries to package all the resource files.
See the example below:
<plugins>
<!-- This plugin provides the capability to package
the artifact in an über-JAR file, including
its dependencies and to shade - i.e. rename -
the packages of some of the dependencies. -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.4</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<artifactSet>
<!-- Signed JAR files-->
<excludes>
<exclude>bouncycastle:bcprov-jdk15</exclude>
</excludes>
</artifactSet>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<!-- Main class -->
<mainClass>com.main.MyMainClass</mainClass>
</transformer>
<!-- Use resource transformers to prevent file overwrites -->
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>properties.properties</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.XmlAppendingTransformer">
<resource>applicationContext.xml</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/cxf/cxf.extension</resource>
</transformer>
<transformer
implementation="org.apache.maven.plugins.shade.resource.XmlAppendingTransformer">
<resource>META-INF/cxf/bus-extensions.xml</resource>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>

You can use the maven-shade plugin to build an über JAR file like below:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

I have long used the Maven assembly plugin, but I could not find a solution to the problem with "already added, skipping". Now, I'm using another plugin - onejar-maven-plugin. An example is below (mvn package builds the JAR file):
<plugin>
<groupId>org.dstovall</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.3.0</version>
<executions>
<execution>
<configuration>
<mainClass>com.company.MainClass</mainClass>
</configuration>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
You need to add a repository for that plugin:
<pluginRepositories>
<pluginRepository>
<id>onejar-maven-plugin.googlecode.com</id>
<url>http://onejar-maven-plugin.googlecode.com/svn/mavenrepo</url>
</pluginRepository>
</pluginRepositories>

You can add the following to your pom.xml file:
<build>
<defaultGoal>install</defaultGoal>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.1</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.mycompany.package.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>com.mycompany.package.MainClass</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Afterwards you have to switch via the console to the directory, where the pom.xml file is located. Then you have to execute mvn assembly:single and then your executable JAR file with dependencies will be hopefully build. You can check it when switching to the output (target) directory with cd ./target and starting your JAR with a command similar to java -jar mavenproject1-1.0-SNAPSHOT-jar-with-dependencies.jar.
I tested this with Apache Maven 3.0.3.

You can use maven-dependency-plugin, but the question was how to create an executable JAR file. To do that requires the following alteration to Matthew Franglen's response (btw, using the dependency plugin takes longer to build when starting from a clean target):
<build>
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>fully.qualified.MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
<resources>
<resource>
<directory>${basedir}/target/dependency</directory>
</resource>
</resources>
</build>

I went through every one of these responses looking to make a fat executable JAR file containing all dependencies and none of them worked right. The answer is the shade plugin, it’s very easy and straightforward.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.3</version>
<executions>
<!-- Run shade goal on package phase -->
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>path.to.MainClass</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
Be aware that your dependencies need to have a scope of compile or runtime for this to work properly.
This example came from mkyong.com

Another option if you really want to repackage the other JARs contents inside your single resultant JAR is the Maven Assembly plugin. It unpacks and then repacks everything into a directory via <unpack>true</unpack>. Then you'd have a second pass that built it into one massive JAR.
Another option is the OneJar plugin. This performs the above repackaging actions all in one step.

You could combine the maven-shade-plugin and maven-jar-plugin.
The maven-shade-plugin packs your classes and all dependencies in a single JAR file.
Configure the maven-jar-plugin to specify the main class of your executable JAR file (see Set Up The Classpath, chapter "Make The Jar Executable").
Example POM configuration for maven-jar-plugin:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.example.MyMainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
Finally create the executable JAR file by invoking:
mvn clean package shade:shade

It will work like:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>generate-resources</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
Unpacking has to be in the generate-resources phase or it will not be included as resources.

Ken Liu has it right in my opinion. The Maven dependency plugin allows you to expand all the dependencies, which you can then treat as resources. This allows you to include them in the main artifact. The use of the assembly plugin creates a secondary artifact which can be difficult to modify - in my case I wanted to add custom manifest entries. My POM file ended up as:
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
...
<resources>
<resource>
<directory>${basedir}/target/dependency</directory>
<targetPath>/</targetPath>
</resource>
</resources>
</build>
...
</project>

What is the problem with locating shared assembly files with maven-assembly-plugin-2.2.1?
Try using the descriptorId configuration parameter instead of descriptors/descriptor or descriptorRefs/descriptorRef parameters.
Neither of them do what you need: look for the file on classpath.
Of course you need adding the package where the shared assembly resides on the maven-assembly-plugin's classpath (see below).
If you're using Maven 2.x (not Maven 3.x), you may need adding this dependency in top-most parent pom.xml in the pluginManagement section.
See this for more details.
Class: org.apache.maven.plugin.assembly.io.DefaultAssemblyReader
Example:
<!-- Use the assembly plugin to create a zip file of all our dependencies. -->
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2.1</version>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptorId>assembly-zip-for-wid</descriptorId>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>cz.ness.ct.ip.assemblies</groupId>
<artifactId>TEST_SharedAssemblyDescriptor</artifactId>
<version>1.0.0-SNAPSHOT</version>
</dependency>
</dependencies>
</plugin>

To resolve this issue, we will use the Maven Assembly plugin that will create the JAR file together with its dependency JAR files into a single executable JAR file. Just add the below plugin configuration in your pom.xml file.
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.your.package.MainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</build>
After doing this, don’t forget to run the Maven tool with this command:
mvn clean compile assembly:single
Maven - Creating a JAR file together with its dependency JAR files into a single executable JAR file

It may not be a good idea to embed all the dependencies in the project's JAR file itself.
I see the point (ease of deployment / usage), but it depends of the use case of your project (and there may be alternatives (see below)).
If you use it fully standalone, why not?
But if you use your project in other contexts (like in a web application, or dropped in a folder where other JARs are sitting), you may have JAR duplicates in your classpath (the ones in the folder, the one in the JAR files). Maybe not a bid deal, but I usually avoid this.
A good alternative:
deploy your application as a ZIP or WAR file: the archive contains your project's JAR file and all dependent JAR files;
use a dynamic classloader mechanism (see Spring Framework, or you can easily do this yourself) to have a single entry point of your project (a single class to start - see the Manifest mechanism in another answer), which will add (dynamically) to the current classpath all the other needed JAR files.
Like this, with in the end just a manifest and a "special dynamic classloader main", you can start your project with:
java -jar ProjectMainJar.jar com.stackoverflow.projectName.MainDynamicClassLoaderClass

I compared the tree plugins mentioned in this post. I generated two JAR files and a directory with all the JAR files. I compared the results and definitely the maven-shade-plugin is the best.
My challenge was that I have multiple Spring resources that needed to be merged, as well as jax-rs, and JDBC services. They were all merged properly by the shade plugin in comparison with the maven-assembly-plugin. In which case Spring will fail unless you copy them to your own resources folder and merge them manually one time.
Both plugins output the correct dependency tree. I had multiple scopes like test, provide, compile, etc. The test and provided were skipped by both plugins. They both produced the same manifest, but I was able to consolidate licenses with the shade plugin using their transformer.
With the maven-dependency-plugin of course you don't have those problems, because the JAR files are not extracted. But like some other have pointed out, you need to carry one extra file(s) to work properly.
Here is a snip of the pom.xml file:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
<includeScope>compile</includeScope>
<excludeTransitive>true</excludeTransitive>
<overWriteReleases>false</overWriteReleases>
<overWriteSnapshots>false</overWriteSnapshots>
<overWriteIfNewer>true</overWriteIfNewer>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.6</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.rbccm.itf.cdd.poller.landingzone.LandingZonePoller</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-my-jar-with-dependencies</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.4.3</version>
<configuration>
<shadedArtifactAttached>false</shadedArtifactAttached>
<keepDependenciesWithProvidedScope>false</keepDependenciesWithProvidedScope>
<transformers>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/services/javax.ws.rs.ext.Providers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.factories</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.handlers</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.schemas</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
<resource>META-INF/spring.tooling</resource>
</transformer>
<transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
<transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"/>
<transformer implementation="org.apache.maven.plugins.shade.resource.ApacheLicenseResourceTransformer">
</transformer>
</transformers>
</configuration>
<executions>
<execution>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
</plugin>

For anyone looking for options to exclude specific dependencies from the über JAR file, this is a solution that worked for me:
<project...>
<dependencies>
<dependency>
<groupId>org.apache.spark</groupId>
<artifactId>spark-core_2.11</artifactId>
<version>1.6.1</version>
<scope>provided</scope> <!-- <============= -->
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>...</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
It's not a configuration of the mvn-assembly-plugin, but a property of the dependency.

Something that has worked for me was:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>prepare-package</phase>
<goals>
<goal>unpack-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/classes</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<executions>
<execution>
<id>unpack-dependencies</id>
<phase>package</phase>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>SimpleKeyLogger</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
I had an extraordinary case, because my dependency was system one:
<dependency>
..
<scope>system</scope>
<systemPath>${project.basedir}/lib/myjar.jar</systemPath>
</dependency>
I have changed the code provided by user189057 with changes:
maven-dependency-plugin is executed in "prepare-package" phase
I am extracting unpacked classes directly to "target/classes"

This is the best way I found:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.myDomain.etc.MainClassName</mainClass>
<classpathPrefix>dependency-jars/</classpathPrefix>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.5.1</version>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>
${project.build.directory}/dependency-jars/
</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
With this configuration, all dependencies will be located in /dependency-jars. My application has no Main class, just context ones, but one of my dependencies do have a Main class (com.myDomain.etc.MainClassName) that starts the JMX server, and receives a start or a stop parameter. So with this I was able to start my application like this:
java -jar ./lib/TestApp-1.0-SNAPSHOT.jar start

There are millions of answers already. I wanted to add you don't need <mainClass> if you don't need to add entryPoint to your application. For example, APIs may not have necessarily have a main method.
Maven plugin configuration
<build>
<finalName>log-enrichment</finalName>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
Build
mvn clean compile assembly:single
Verify
ll target/
total 35100
drwxrwx--- 1 root vboxsf 4096 Sep 29 16:25 ./
drwxrwx--- 1 root vboxsf 4096 Sep 29 16:25 ../
drwxrwx--- 1 root vboxsf 0 Sep 29 16:08 archive-tmp/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 classes/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 generated-sources/
drwxrwx--- 1 root vboxsf 0 Sep 29 16:25 generated-test-sources/
-rwxrwx--- 1 root vboxsf 35929841 Sep 29 16:10 log-enrichment-jar-with-dependencies.jar*
drwxrwx--- 1 root vboxsf 0 Sep 29 16:08 maven-status/

I wanted to migrate my Spring application (using Apereo Foundation's CAS client) to Spring Boot 1.5. I ran into many problems, like:
no main manifest attribute, in target/cas-client-web.jar
I tried to make one unique JAR file with all dependencies. After searching on the Internet, I was able to do it with these lines:
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<fork>true</fork>
<mainClass>${start-class}</mainClass>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>${start-class}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
start-class is my main class:
<properties>
<java.version>1.8</java.version>
<start-class>com.test.Application</start-class>
</properties>
And my Application is:
package com.test;
import java.util.Arrays;
import com.test.TestProperties;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
#SpringBootApplication
#EnableAutoConfiguration
#EnableConfigurationProperties({TestProperties.class})
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
return args -> {
System.out.println("Let's inspect the beans provided by Spring Boot:");
String[] beanNames = ctx.getBeanDefinitionNames();
Arrays.sort(beanNames);
for (String beanName : beanNames) {
System.out.println(beanName);
}
};
}
}

To create an executable JAR from the command line itself, just run the below command from the project path:
mvn assembly:assembly

This could also be an option. You will be able to build your JAR file.
<build>
<plugins>
<plugin>
<!-- Build an executable JAR -->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>WordListDriver</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>

I tried the most upvoted answer here and was able to get the JAR file runnable. But the program didn't run correctly. I do not know what the reason was. When I try to run from Eclipse, I get a different result, but when I run the JAR file from command line I get a different result (it crashes with a program-specific runtime error).
I had a similar requirement as the OP just that I had too many (Maven) dependencies for my project. Fortunately, the only solution that worked for me was that using Eclipse. It is very simple and very straightforward. This is not a solution for the OP, but it is a solution for someone who has a similar requirement, but with many Maven dependencies,
Just right-click on your project folder (in Eclipse) and select Export
Then select Java → Runnable JAR
You will be asked to choose the location of the JAR file
Finally, select the class that has the Main method that you want to run and choose *Package dependencies with the JAR file and click Finish

Add to file pom.xml:
<dependency>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
</dependency>
And
<plugin>
<groupId>com.jolira</groupId>
<artifactId>onejar-maven-plugin</artifactId>
<version>1.4.4</version>
<executions>
<execution>
<goals>
<goal>one-jar</goal>
</goals>
</execution>
</executions>
</plugin>
That’s it. Next, the mvn package will also create one fat JAR additionally, including all dependency JAR files.

The maven-assembly-plugin worked great for me.
I spent hours with the maven-dependency-plugin and couldn't make it work. The main reason was that I had to define the artifact items explicitly in the configuration section which should be included as it is described in the documentation.
There is an example there for the cases when you want to use it like: mvn dependency:copy, where there are not included any artifactItems, but it doesn't work.

I tried multiple solutions, but this is the one that worked perfectly in the scenario where we wanted to create a non-executable fat JAR file with all internal dependencies for external systems having no previous relevance. A production scenario was tested.
Include this in the pom.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
The command to run to build the fat JAR file:
mvn assembly:assembly

This blog post shows another approach with combining the maven-jar and maven-assembly plugins. With the assembly configuration XML file from the blog post it can also be controlled if dependencies will be expanded or just be collected in a folder and referenced by a classpath entry in the manifest:
The ideal solution is to include the jars in a lib folder and the manifest.mf file of the main jar include all the jars in classpath.
And exactly that one is described here: Executable JAR file with dependent JAR files using Maven

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

How to compile a Maven Java with the librarys? [duplicate] - java

You can use the maven-shade-plugin. After configuring the shade plugin in your build the command mvn package will create one single jar with all dependencies merged into it.

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