Create multiple runnable Jars (with dependencies included) from a single Maven project [duplicate]

Question

This question already has an answer here:

• Creating Two Executable Jars Using maven-assembly-plugin 1 answer

I have a single maven project that has multiple main classes. I want to generate runnable Jars (that include all dependencies) out of these project. I currently have the following build configuration (using maven.assembly):

<build>
<plugins>
    <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <configuration>
            <archive>
                <manifest>
                    <mainClass>classpath.to.my.mainClass</mainClass>
                </manifest>
            </archive>
            <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
            </descriptorRefs>
        </configuration>
    </plugin>
</plugins>
</build>

Is their a way to achive this with maven-assembly? If not, what is the simplest way to achive my goal?

Answer 1

You can do it. You'll need a separate execution for each artifact that you're building (i.e., give each its own id but you can leave the phase as default), and you'll need to specify the finalName and archive/manifest/mainClass for each.

<build>
<plugins>
    <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <executions>
          <execution>
            <id>build-a</id>
            <configuration>
              <archive>
                <manifest>
                  <mainClass>foobar.Aclass</mainClass>
                </manifest>
              </archive>
              <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
              </descriptorRefs>
              <finalName>foobar_a.jar</finalName>
            </configuration>
          </execution>
          <execution>
            <id>build-b</id>
            <configuration>
              <archive>
                <manifest>
                  <mainClass>foobar.Bclass</mainClass>
                </manifest>
              </archive>
              <descriptorRefs>
                <descriptorRef>jar-with-dependencies</descriptorRef>
              </descriptorRefs>
              <finalName>foobar_b.jar</finalName>
            </configuration>
          </execution>
        </executions>
    </plugin>
</plugins>
</build>

Answer 2

I wasn't able to solve this problem with the maven-assembly-plugin in a satisfying way, so I went for a different solution. I used the onejar-maven-plugin:

<build>
  <plugins>
  <plugin>
    <groupId>org.dstovall</groupId>
    <artifactId>onejar-maven-plugin</artifactId>
    <version>1.4.4</version>
    <executions>
      <execution>
        <id>build-first</id>
          <configuration>
            <mainClass>classpath.to.first.Main</mainClass>
            <attachToBuild>true</attachToBuild>
            <classifier>onejar</classifier>
            <filename>first-runnable.jar</filename>
          </configuration>
          <goals>
            <goal>one-jar</goal>
          </goals>
        </execution>
      <execution>
        <id>build-second</id>
          <configuration>
            <mainClass>classpath.to.second.Main</mainClass>
            <attachToBuild>true</attachToBuild>
            <classifier>onejar</classifier>
            <filename>second-runnable.jar</filename>
          </configuration>
          <goals>
            <goal>one-jar</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

<pluginRepositories>
  <pluginRepository>
     <id>onejar-maven-plugin.googlecode.com</id>
     <url>http://onejar-maven-plugin.googlecode.com/svn/mavenrepo</url>
  </pluginRepository>
</pluginRepositories>

Answer 3

The top answer works if you are not using any configuration (or any resource, for that matter) that gets bundled into your jar file (e.g., configuration for Spring Framework auto-bindings).

Fortunately, this solution also works with maven-shade-plugin and you don't have that aforementioned issue with onejar-maven-plugin.

Also, maven-shade-plugin is actively being maintained as opposed to onejar-maven-plugin which is in the purgatory that is googlecode.

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-shade-plugin</artifactId>
  <version>2.4.1</version>
  <executions>
    <execution>
      <id>build-first</id>
      <phase>package</phase>
      <goals>
         <goal>shade</goal>
      </goals>   
      <configuration>
        <transformers>
          <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">                        
            <mainClass>classpath.to.first.Main</mainClass>
          </transformer>
        </transformers>
        <finalName>first-runnable</finalName>
      </configuration>        
    </execution>
    <execution>
      <id>build-second</id>
      <phase>package</phase>
      <goals>
         <goal>shade</goal>
      </goals>   
      <configuration>
        <transformers>
          <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">                        
            <mainClass>classpath.to.second.Main</mainClass>
          </transformer>
        </transformers>
        <finalName>second-runnable</finalName>
      </configuration>  
    </execution>
  </executions>
</plugin>

Answer 4

To specify a little more previous answer that was very helpful to me, you need to add phase package and goal assembly and run mvn run clean package, pom is as follows :

<plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <executions>
                <execution>
                    <id>build-a</id>
                    <configuration>
                        <archive>
                            <manifest>
                                <mainClass>firstMainClass</mainClass>
                            </manifest>
                        </archive>
                        <descriptorRefs>
                            <descriptorRef>jar-with-dependencies</descriptorRef>
                        </descriptorRefs>
                        <finalName>a.jar</finalName>
                    </configuration>
                    <phase>package</phase>
                    <goals>
                        <goal>assembly</goal>
                    </goals>
                </execution>
                <execution>
                    <id>build-b</id>
                    <configuration>
                        <archive>
                            <manifest>
                                <mainClass>SecondMainClass</mainClass>
                            </manifest>
                        </archive>
                        <descriptorRefs>
                            <descriptorRef>jar-with-dependencies</descriptorRef>
                        </descriptorRefs>
                        <finalName>b.jar</finalName>
                    </configuration>
                    <phase>package</phase>
                    <goals>
                        <goal>assembly</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>