Building a runnable jar with Maven 2

Question

I'm relatively new to the Maven mantra, but I'm trying to build a command-line runnable jar with Maven. I've setup my dependencies, but when I run mvn install and attempt to run the jar, two things happen. First, no main class is found, which is correctable. When I've corrected this, I get errors on run stating that classes cannot be found.

Maven is not packaging my dependency libraries inside of the jar, so I am unable to run the jar as a stand-alone application. How do I correct this?

Answer 1

The easiest way to do this would be to create an assembly using the maven-assembly-plugin and the predefined jar-with-dependencies descriptor. You'll also need to generate a manifest with a main-class entry for this uber jar. The snippet below shows how to configure the assembly plugin to do so:

<build>   <plugins>     <plugin>       <artifactId>maven-assembly-plugin</artifactId>       <configuration>         <descriptorRefs>           <descriptorRef>jar-with-dependencies</descriptorRef>         </descriptorRefs>         <archive>           <manifest>             <mainClass>fully.qualified.MainClass</mainClass>           </manifest>         </archive>       </configuration>     </plugin>   </plugins> </build> 

Then, to generate the assembly, just run:

mvn assembly:assembly 

If you want to generate the assembly as part of your build, simply bind the assembly:single mojo to the package phase:

<build>   <plugins>     <plugin>       <artifactId>maven-assembly-plugin</artifactId>       <configuration>         <descriptorRefs>           <descriptorRef>jar-with-dependencies</descriptorRef>         </descriptorRefs>         <archive>           <manifest>             <mainClass>fully.qualified.MainClass</mainClass>           </manifest>         </archive>       </configuration>       <executions>         <execution>           <phase>package</phase>           <goals>             <goal>single</goal>           </goals>         </execution>       </executions>     </plugin>   </plugins> </build> 

And simply run:

mvn package