Develop Reference

Compiling mysql dependincy with maven Spigot

I personally prefer to keep my coding problem off of here unless I think I'm stumped. I'm trying to add the mysql java dependency to my project (I'm coding a Minecraft-Spigot 1.12.2 plugin).
I've been coding MySQL for years but I've never had to use it with Java until now so I'm following this tutorial: https://www.spigotmc.org/wiki/connecting-to-databases-mysql/
Which redirected me to this page: https://mvnrepository.com/artifact/mysql/mysql-connector-java/8.0.26
Naturally adding a Maven dep is easy enough you just copy and paste it! Beyond that, I'm not very in tune with the inner workings of the system.
Whenever I compile (it does in-fact compile without throwing any fits) and upload it to my servers I get this error: java.lang.NoClassDefFoundError: com/mysql/cj/jdbc/MysqlDataSource. Now, I know that this has to do with the class being undefined or something. So obviously, I searched the error code. A lot of the problems I saw didn't seem to apply to me.
I double checked and I DO see mysql-connector-java inside of my "External Libraries" section in my IDE (InteliJ IDEA)
I also saw some people sending this link: How can I create an executable JAR with dependencies using Maven?
Which, the answer didn't seem to help me out either (unless I missed something).
My hope is that by sending my file someone can help me out here?
I've seen some people mention that it could be a problem with a classpath? How exactly can I go about fixing that (if it is the problem). I couldn't seem to find anything to help me with that problem (tho in this case classpath is a little over my head. Def want to read up on it more in the future).
Here's my pom.xml any helpful assistance is appreciated!
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>example</artifactId>
<version>1.12.2-SNAPSHOT</version>
<packaging>jar</packaging>
<name>example</name>
<properties>
<java.version>1.8</java.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>8</source>
<target>8</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.2.4</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<createDependencyReducedPom>false</createDependencyReducedPom>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
</build>
<repositories>
<repository>
<id>spigotmc-repo</id>
<url>https://hub.spigotmc.org/nexus/content/repositories/snapshots/</url>
</repository>
<repository>
<id>sonatype</id>
<url>https://oss.sonatype.org/content/groups/public/</url>
</repository>
<repository>
<id>dmulloy2-repo</id>
<url>https://repo.dmulloy2.net/repository/public/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>org.spigotmc</groupId>
<artifactId>spigot-api</artifactId>
<version>1.12.2-R0.1-SNAPSHOT</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.comphenix.protocol</groupId>
<artifactId>ProtocolLib</artifactId>
<version>4.6.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.25</version>
</dependency>
</dependencies>
</project>

Did you use the right SNAPSHOT jar? Because that should work for you and
jar tf <the snapshot>.jar | find "com/mysql/cj/jdbc/MysqlDataSource"
on Windows or
jar tf <the snapshot>.jar | grep "com/mysql/cj/jdbc/MysqlDataSource"
on *nix should find that 'missing' class in the jar

Lambda error during maven build

I am using Maven build to build my project(using Eclipse IDE).
I have put jdk1.8 as default jdk, but still, I am getting an error as the source is 1.6.
Is there a configuration problem I am missing out? Please let me know?
(use -source 8 or higher to enable lambda expressions)
1. "clean install" as goals in "Run Configurations" in Eclipse.
2.pom.xml file
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mastercard.ayman</groupId>
<artifactId>Spring_MVC</artifactId>
<version>0.0.1-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.2.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-rest-webmvc</artifactId>
<version>3.0.7.RELEASE</version>
</dependency>
</dependencies>
<repositories>
<repository>
<id>spring-libs-release</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/libs-release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</project>
Compiler is JavaSE-1.8

Either set the maven-compiler-plugin as #Horst says or set the maven.compiler.source and maven.compiler.target properties like this.
<project ...>
...
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
...
</dependencies>
<build>
...
</build>
</project>

This is something I have dealt with too many times.
Could you post the following things as an answer?
Your current build command/query.
Your pom.xml code.
Your compiler version.
With these file(s) I could help you further to resolve your problem!

Setting the JDK in eclipse is only half the story, as maven manages the compiler itself.
Try adding the maven compiler plugin to you build configuration:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.2</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>

404 error when Running Jar [Spring Boot]

i'm stuck with a problem and can't figure what's wrong.
I have a multi-module maven project, using spring boot.
Layout of the project
I'm using STS, and everything is fine. If i run the app, it runs the server, and i have my index in localhost:8080.
However, i'd like to generate a jar from this. So, i'm using mvn clean install. It generates a jar in /target. The layout in the jar is fine, with the source, and the source of the client.
Then, i'm running my jar with java -jar myJar.jar. The server runs properly, but when i'm trying to access to the site, i have an error 404. It can't find the views.
The error :
Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.
Wed Dec 28 19:45:52 CET 2016
There was an unexpected error (type=Not Found, status=404).
No message available
Here's my pom.xml of the web and client module.
Client pom.xml
<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>projet.si</groupId>
<artifactId>projetsi</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>projet.si</groupId>
<artifactId>ProjetSI_client</artifactId>
<name>ProjetSI_client</name>
<url>http://maven.apache.org</url>
<build>
<resources>
<resource>
<directory>${basedir}/src/main/webapp</directory>
</resource>
<resource>
<directory>${project.build.directory}/dist</directory>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<configuration>
<outputDirectory>${project.build.directory}/classes/</outputDirectory>
</configuration>
</plugin>
</plugins>
</build>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
</project>
Module web pom.xml :
<?xml version="1.0"?>
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>projet.si</groupId>
<artifactId>projetsi</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<groupId>projet.si</groupId>
<artifactId>ProjetSI_web</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>ProjetSI_web</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<artifactId>spring-boot-starter-tomcat</artifactId>
<groupId>org.springframework.boot</groupId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>projet.si</groupId>
<artifactId>ProjetSI_business</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>projet.si</groupId>
<artifactId>ProjetSI_client</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<configuration>
<outputDirectory>${project.build.directory}/dist/</outputDirectory>
<includeArtifactIds>ProjetSI_client</includeArtifactIds>
<includeGroupIds>projet</includeGroupIds>
<includes>**/*</includes>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
I've search over stackoverflow but haven't find anything :/
If you need more details or code, ask me i'll edit.
Thanks !

Please check if you have any method attached to the url your are hitting from the browser. 404 - not found, the resource or url you are trying to access does not exists. You should have a Method of a controller mapped to "/" or whatever url you are hitting.

Maven EAR multimodule project not packaging persistence.xml

I`m working in a EAR project with Maven which has 2 modules. Images speaks louder than words, so let me show you the structure:
Parent pom project and modules
sigea-model contains model, repository and service layers (The "M" in MVC). sigea-web contains web pages and controller beans (VC) and sigea-ear is just a wrapper to package the other 2 modules in a EAR package.
Configuration files in modules
As you can see, sigea-ear has an empty META-INF folder. Both beans.xml files in sigea-model and sigea-web are just empty marker files because AFAIK, CDI by default search in all annotated classes (but this is not the problem right now). persistence.xml is a simple file which uses JTA transactions with a connection pool (which is working because I ping from the Glassfish's admin console and is successful).
Finally, when I package the application I get the following:
As you can see, there's no persistence.xml. All this came out because I deployed the application successfully but in the first click I got the Exception
javax.ejb.TransactionRolledbackLocalException: Exception thrown from bean
...
Caused by: java.lang.IllegalStateException: Unable to retrieve EntityManagerFactory for unitName null
Here are my pom files:
pom.xml[sigea-app] (parent project)
<project ...>
<modelVersion>4.0.0</modelVersion>
<groupId>ar.edu.unt.sigea</groupId>
<artifactId>sigea-app</artifactId>
<version>1.0</version>
<packaging>pom</packaging>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<modules>
<module>sigea-model</module>
<module>sigea-web</module>
<module>sigea-ear</module>
</modules>
<build>
<pluginManagement>
...
</pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencyManagement>
<!-- I suppress some lines for brevity -->
<dependencies>
<dependency>
<artifactId>sigea-model</artifactId>
</dependency>
<dependency>
<artifactId>sigea-model</artifactId>
<type>ejb</type>
</dependency>
<dependency>
<artifactId>sigea-model</artifactId>
<type>test-jar</type>
<scope>test</scope>
</dependency>
<dependency>
<artifactId>sigea-web</artifactId>
<type>war</type>
</dependency>
<dependency>
<artifactId>sigea-web</artifactId>
<type>pom</type>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
...
</dependencies>
</project>
pom.xml[sigea-ear]
<project ...>
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>ar.edu.unt.sigea</groupId>
<artifactId>sigea-app</artifactId>
<version>1.0</version>
</parent>
<artifactId>sigea-ear</artifactId>
<packaging>ear</packaging>
<dependencies>
<dependency>
<artifactId>sigea-model</artifactId>
<type>ejb</type>
</dependency>
<dependency>
<artifactId>sigea-web</artifactId>
<type>war</type>
</dependency>
<dependency>
<artifactId>sigea-web</artifactId>
<type>pom</type>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-ear-plugin</artifactId>
<configuration>
<defaultLibBundleDir>lib/</defaultLibBundleDir>
<skinnyWars>true</skinnyWars>
<modules>
<webModule>
<groupId>${project.groupId}</groupId>
<artifactId>sigea-web</artifactId>
<contextRoot>/sigea</contextRoot>
</webModule>
<ejbModule>
<groupId>${project.groupId}</groupId>
<artifactId>sigea-model</artifactId>
</ejbModule>
</modules>
</configuration>
</plugin>
</plugins>
</build>
</project>
pom.xml[sigea-web]
<project ...>
<modelVersion>4.0.0</modelVersion>
<parent>
<artifactId>sigea-app</artifactId>
<groupId>ar.edu.unt.sigea</groupId>
<version>1.0</version>
</parent>
<groupId>ar.edu.unt.sigea</groupId>
<artifactId>sigea-web</artifactId>
<version>1.0</version>
<packaging>war</packaging>
<name>sigea-web</name>
<dependencies>
<!-- Some dependencies including sigea-model -->
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<configuration>
<packagingExcludes>WEB-INF/lib/*.jar</packagingExcludes>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>
</project>
pom.xml[sigea-model] is not important as it just defines some dependencies for test and is configured to generate a package with the test classes, which are used in sigea-web for test purposes also.
Finally the question: What's failing in my configuration that doesn't package the persistence.xml file? If that's not the problem for the IllegalStateException with the message shown above: What are posible causes for that exception?
Thanks in advance for your answers.

I solved the problem by changing a dependency. In sigea-model I had
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>5.1.0.Final</version>
<scope>test</scope>
</dependency>
Which I used to manage the persistence context for my test methods. I didnt inquire very much in the Glassfish JPA provided implementation but maybe it's Eclipse Link instead of Hibernate. Apparently there are some incompatibility issue between those libraries. I movedhibernate-entitymanager` to compile scope, like this:
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>5.1.0.Final</version>
</dependency>
And now the projects compile with no problem. It was also useful the comment made by khmarbaise, it simplified the project configuration, thank you very much.

Spring application context unable to find property files under maven resources folder

I am using maven in my project & I've put database.properties file under
maven resources folder.
I am accessing it in spring application context
<context:property-placeholder location="classpath:database.properties" />
But I don't understand why I am getting this file not found error on server start.
Could not load properties; nested exception is
java.io.FileNotFoundException: class path resource
[database.properties] cannot be opened because it does not exist
To my knowledge whatever resource is put under resources folder it is added to the classpath automatically by maven.
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.myapp</groupId>
<artifactId>myapp</artifactId>
<packaging>war</packaging>
<version>0.0.1-SNAPSHOT</version>
<name>myapp Maven Webapp</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>myapp</finalName>
</build>
</project>
NOTE: Seems like there is some problem with the M2E plugin of eclipse luna. Executed the same code in Juno & it worked fine.

That's not enough to build a deployable war file with maven. You need at least the war plugin. There's a thorough tutorial here:
http://crunchify.com/how-to-create-a-war-file-from-eclipse-using-maven-plugin-apache-maven-war-plugin-usage/
Your pom will look something like below, and you'll need to run mvn clean install against that.
Also I see you have a spring app, where are the spring dependencies in the pom file?
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>CrunchifyTutorial</groupId>
<artifactId>CrunchifyTutorial</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>war</packaging>
<build>
<sourceDirectory>src</sourceDirectory>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<version>2.4</version>
<configuration>
<warSourceDirectory>WebContent</warSourceDirectory>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
</dependency>
</dependencies>
</project>