Develop Reference

Java Project with modules in one Jar

I have a project called BigProject.
The structure is:
BigProject
-firstModule
--pom.xml
-secondModule
--pom.xml
-thirdModule
--pom.xml
-pom.xml
I want to create a unique jar called BigProject.jar
At the moment, if I do a clean install, I have returned a jar for each module.
Can you explain me how to do?
thanks

Well you'd need a custom class loader for that. Thankfully folks have already contributed some plugins to ease up your life. You can have a look over Ant's create jar task or spring-boot's repackage goal, whatever stays convenient for you. Example below:
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>2.0.1.RELEASE</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>

Each module-info.java which lives in the default package will be compiled to module-info.class.
Therefore, one JAR cannot contain multiple modules.

How to create an additional JAR for a specific folder with maven

I have a maven project, I need to generate three separate jars
one for the main application (default)
one for the source code (maven-source-plugin)
and one for my app documentation which reside in target/docs
Question: How can I create a jar containing only the target/docs folder?

You could add the following to your maven pom.xml file, build/plugins section:
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.1</version>
<executions>
<execution>
<configuration>
<classifier>docs</classifier>
<classesDirectory>${project.build.directory}/docs</classesDirectory>
<includes>**/*</includes>
</configuration>
<id>pack-docs</id>
<phase>package</phase>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
Which is basically:
Using the maven-jar-plugin, jar goal to pack a new artefact for the project
Adding (or attaching) it as a classifier (docs suffix appended to the normal convention for project artefacts, e.g. artifactId-version.jar)
Setting the target\docs as source of files, using the standard ${project.build.directory} property instead of target (which is its value by default)
Running
mvn clean package
You would then have as part of the output
The jar file normally created, e.g. sample-project-1.0.0-SNAPSHOT.jar
The new docs file, e.g. sample-project-1.0.0-SNAPSHOT-docs.jar

build-helper-maven-plugin adding additional source

I am trying to add an additional source folder to my current maven project by using build-helper-maven plugin.
This source folder contains some common classes, like utility classes.
For that, here is my relevant pom.xml
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>1.9.1</version>
<executions>
<execution>
<id>add-source</id>
<phase>generate-sources</phase>
<goals>
<goal>add-source</goal>
</goals>
<configuration>
<sources>
<source>C:/Users/CommonIncludes/src</source>
</sources>
</configuration>
</execution>
</executions>
</plugin>
Eclipse is showing the following error :
Build path entry is missing.
Project->Right Click->Java build path->Source->
Project/Users/CommonIncludes/src(missing)
Here the additional source location : "C:/Users/CommonIncludes/src" is outside of the workspace of the current project. But eclipse always treating this as a location from current project.
I am using Eclipse 4.3 and m2e.
How can I overcome this error through MAVEN, so that Eclipse can identify the linked source from correct location.? Or is there any alternate way to do this using MAVEN?
Any help will be greatly appreciated. Thanks in advance.

Found it in an alternate way..works great.!
Steps include
1. Removed build-helper-maven-plugin from pom .
2. Created another maven project and added the common classes in it. Added maven-source-plugin in this pom to generate sources.
3. To the same pom, added maven-dependency-plugin to copy this generated sources to the desired location (My project's src/main/java).
4. Run a maven build for common classes project.
Now the common code in my project. Thanks.

I had a lot of inconsistent trouble with this plugin.
by far the simplest workaround in my case was simply to apply the addition via the standard 'resources' options.
hope this helps someone.
<build>
<resources>
...
<resource>
<directory>${project.build.directory}/generated-sources</directory>
<targetPath>${project.build.outputDirectory}</targetPath>
</resource>
</build>

maven copy a particular dependency jar to a specific directory in the .war file

I am trying out a Simple Java Web Start project based on the Oracle Tutorial. I am using maven to package it as a webapp and deploy it to application server. The full source code is available here
https://github.com/KiranMohan/dynamic-tree-javaws-sample-project
The maven project structure is like
parent
|--lib
|--webapp
The webapp module is a maven war module. It is required to package lib.jar at the root of webapp.war. NOT under WEB-INF/lib.
How to achieve this in maven?

I found that the right way to do this is to use the maven-dependency-plugin.
Since "lib.jar" is not used in the compile phase of "webapp" module, it is only a package time dependency. Using maven-dependency-plugin, I can copy lib.jar to any required directory during the prepare-package phase. The maven-war package would then include the lib.jar in the .war package.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy</id>
<phase>prepare-package</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<artifactItems>
<artifactItem>
<groupId>[ group id ]</groupId>
<artifactId>[artifact id]</artifactId>
<version>[ version ]</version>
<outputDirectory>${project.build.directory}/${project.artifactId}</outputDirectory>
</artifactItem>
</artifactItems>
<!-- other configurations here -->
</configuration>
</execution>
</executions>
</plugin>
Update:
There is a webstart-maven-plugin that does a better job of packaging javaws applications. See my sample project
https://github.com/KiranMohan/dynamic-tree-javaws-sample-project
for details

Well how i said in the comments for sake of readability here is a part of the answer:
Since Maven will always store the dependencies of a web project under its WEB-INF/lib folder by default i (i am no Maven expert ...) would try to place my lib.jar inside the /target folder of the project before the phase package is executed.
NOTE: I havent tried it out so you will have to adjust the paths - expecially the output path so your lib.jar is placed properly to be packed into the root of the war (e.g. if you open your war there will be a lib.jar next to folders such as WEB-INF).
<!--
lets assume the root of my project would be under C:/devjba/projectX this equals the maven
variable ${project.basedir}.
from there the output-directory would be located under C:/devjba/projectX/target which equals the
maven variable ${project.build.directory}. This is the location a .war would be placed in after
the build
lets assume the required jar lib.jar is located under C:/devjba/projectX/misc which would equal to
the expression: ${project.basedir}/misc
-->
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>2.6</version>
<executions>
<execution>
<id>foo</id>
<!-- may adjust to another phase before package but make sure your plugin is bound to a phase
because otherwise it wont be invoked during build! Now its bound to the first phase of the
default lifecycle for packaging type war -->
<phase>process-resources</phase>
<goals>
<!-- use the copy-resources goal of this plugin - it will copy resources :) -->
<goal>copy-resources</goal>
</goals>
<configuration>
<!-- this points to /target of the current project, you may adjust it to wherever it must be placed to be packed into the root of the war (just try&error) -->
<outputDirectory>${project.build.directory}</outputDirectory>
<resources>
<resource>
<!-- this points to a folder /misc under the project root where we expect the lib.jar -->
<directory>${project.basedir}/misc</directory>
<!-- unless you specify what to include anything of the above directory will be included -->
<includes>
<include>lib.jar</include>
</includes>
</resource>
</resources>
</configuration>
</execution>
</executions>
</plugin>
As i said i have no experience in signing JARs at all but there is a plugin called maven-jarsigner-plugin which i guess will do the job (i would sign it, then move it, then package the war) with a manual - i recomend you try to configure it according to my "example configuration of the maven-resource-plugin and post a new question directly containing your two plugin configurations. Dont forget to link to this question in that case. And also leave this question open so someone with a better approach may correct my way).

maven properties-maven-plugin doesn't work when deploying artifact to Nexus

I am using properties-maven-plugin to read a external property file under root dir to maintain the version of parent module since there are quite a number of sub-modules in my project and the dependency tree is kinda deep.
It works fine when I build locally and install the artifacts into local repo but got the 401 error when I try to use "mvn clean deploy" to publish them to Nexus. I am pretty sure this is caused by the ineligible artifact name(releaseurl/{external.version}), external.version is supposed to be the property read from the external file. However, it ended up not being read and it just worked fine when I explicitly declare the version in the project.parent.version tag. Any thoughts or workaround? or even how you handle the version control when trying to use same version for parent and child in all the modules when dealing with a multi-module porject.
The maven pom for the plugin is as below, I saw some comments online regarding the phase, not sure if it will work if change initialize to something else:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>properties-maven-plugin</artifactId>
<executions>
<execution>
<phase>initialize</phase>
<goals>
<goal>read-project-properties</goal>
</goals>
<configuration>
<files>
<file>external-file.properties</file>
</files>
</configuration>
</execution>
</executions>
</plugin>