Plexus Container Annotations and Maven 2 Mojos

I’ll make it short: it’s a mess. You can’t use plexus container 1.5-tooling (with java annotations), if you have to load your components in a plexus 1.0.x-container – which is the case, if your components are utilized in a Maven 2.2.x Mojo. This is simply because plexus container 1.5.x uses “default” as a default role-hint, while NULL is the default in plexus 1.0.x.

But you can use the old tooling, plexus-maven-plugin. But by default it fails if it sees any annotation in your source code, because it uses a version of qdox that doesn’t know annotations yet.

Also, when generating the component descriptor it doesn’t merge with the manually defined one in src/resources (the new one does).

And since, by default, the merge-descriptors goal runs before descriptor (generate) goal, you have to do some back flips to get that running too.

Well here is a configuration that works. At least in my project. Today.

<plugin>
  <groupId>org.codehaus.plexus</groupId>
  <artifactId>plexus-maven-plugin</artifactId>
  <version>1.3.8</version>
  <dependencies>
    <dependency>
      <groupId>com.thoughtworks.qdox</groupId>
      <artifactId>qdox</artifactId>
      <version>1.12</version>
    </dependency>
  </dependencies>
  <executions>
    <execution>
      <phase>process-classes</phase>
      <goals>
        <goal>descriptor</goal>
        <goal>merge-descriptors</goal>
      </goals>
      <configuration>
        <!-- descriptor config -->
        <outputDirectory>${project.build.directory}</outputDirectory>
        <fileName>plexus/auto-components.xml</fileName>

        <!-- merge config -->
        <descriptors>
          <descriptor>${project.build.directory}/plexus/auto-components.xml</descriptor>
          <descriptor>${basedir}/src/main/resources/META-INF/plexus/components.xml</descriptor>
        </descriptors>
      </configuration>
    </execution>
  </executions>
</plugin>

Note: If you only want to use automatic descriptors, remove all <configuration>…</configuration> contents. The defaults will work then.

You can define that in build/pluginManagement/plugins in your parent pom. Then in your project pom, you just put these four lines in build/plugins:

<plugin>
  <groupId>org.codehaus.plexus</groupId>
  <artifactId>plexus-maven-plugin</artifactId>
</plugin>