The maven-antrun-plugin has only one goal, run.
This allows maven 2 to run ant tasks. To do so, there must be an existing project and the maven-antrun-plugin must have its <tasks> tag configured (although it would still execute without the <tasks> tag, it would not do anything). Below is the template for the maven-antrun-plugin's pom.xml.
<project>
[...]
<build>
<plugins>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<phase> <!-- a lifecycle phase --> </phase>
<configuration>
<tasks>
<!--
Place any ant task here. You can add anything
you can add between <target> and </target> in a
build.xml.
-->
</tasks>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
[...]
</project>
Moreover, you can add a script to each lifecycle phase, by duplicating the <execution/> section and specifying a new phase.
Below you can see how to indicate that ant has generated some more java source that needs to be included in the compilation phase. Note that the compile phase follows the generate-sources phase in the lifecycle.
<project>
<modelVersion>4.0.0</modelVersion>
<artifactId>my-test-app</artifactId>
<groupId>my-test-group</groupId>
<version>1.0-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<phase>generate-sources</phase>
<configuration>
<tasks>
<!--
Place any ant task here. You can add anything
you can add between <target> and </target> in a
build.xml.
-->
</tasks>
<sourceRoot>${project.build.directory}/generated-sources/main/java</sourceRoot>
<testSourceRoot>${project.build.directory}/generated-sources/test/java</testSourceRoot>
</configuration>
<goals>
<goal>run</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Of course, you can put whatever folder you prefer. The folders in the example above arehandy because they are deleted when you clean since they are in the build directory (which is, by default, "target").
<sourceRoot/> adds a single folder to the list of folders that get compiled with the program source code (compile).
<testSourceRoot/> adds a single folder to the list of folders that get compiled with the test source code (test-compile).
Some Ant expressions have their respective counterparts in Maven. Thus, one can simply invoke the corresponding maven expression instead of using maven-antrun-plugin to avoid the unneccessary overhead.