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 Using Plugin Tools Java5 Annotations
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 Olivier Lamy
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 2012-05-14
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Using Plugin Tools Java Annotations

 Since version 3.0 of the maven-plugin-plugin, you can use Java5 annotations to generate the 
 plugin descriptor file.

 <<NOTE>> With annotations, your Mojo super class does not have to be in the same project: provided that the super class also uses annotations, it
 can now come from reactor projects or external dependencies. By default all dependencies are scanned, but this can be reduced with the <<<mojoDependencies>>>
 parameter. BUT as javadoc doclets are still useful for goals and parameters description, <<<@since>>> and <<<@deprecated>>>, the sources are still scanned. So if you use an external
 dependency, you must still provide an artifact with sources (<<<sources>>> classifier) to provide documentation (the tooling will skip error if this artifact 
 sources is missing).

* Annotations

  Information for plugin descriptor generation is specified using 4 annotations:

  * 2 class level annotations:

    * <<<@Mojo>>>: This annotation will mark your class as a Mojo,

    * <<<@Execute>>>: Used if your Mojo needs to fork a lifecycle,

    []

  * 1 field or method level annotations:

    * <<<@Parameter>>>: Used to configure your Mojo parameters,

    []

  * 1 field level annotations:

    * <<<@Component>>>: Used to configure injection of Plexus components or Maven context components.

    []

  []

  For more information on these annotations, see the
  {{{../../maven-plugin-tools-annotations/index.html#Supported_Annotations}corresponding documentation}}.

  Notice that Plugin Tools Java Annotations are named after Plugin Tools Javadoc Tags
  with following little differences:

*-------------------------------+---------------+
|| {{{../../maven-plugin-tools-java/index.html}Plugin Tools Javadoc Tags}} || {{{../../maven-plugin-tools-annotations/index.html}Plugin Tools Java Annotation}} ||
*-------------------------------+---------------+
| <<<@goal "goal-name">>>       | <<<@Mojo( name = "goal-name" )>>>
*-------------------------------+---------------+
| <<<@phase "\<phase-name\>">>> | <<<@Mojo( defaultPhase = LifecyclePhase.\<phase\> )>>>
*-------------------------------+---------------+

* POM configuration

  To be able to use these Java annotations, you need to add to your plugin POM
  <<<maven-plugin-annotations>>> dependency, preferably with <<<provided>>> scope.

+-----+
<project>
  ...
  <packaging>maven-plugin</packaging>
  ...
  <dependencies>
    <!-- dependencies to annotations -->
    <dependency>
      <groupId>org.apache.maven.plugin-tools</groupId>
      <artifactId>maven-plugin-annotations</artifactId>
      <version>${project.version}</version>
      <scope>provided</scope> <!-- annotations are not used at runtime because @Retention(value=CLASS), they are needed only to build the plugin -->
    </dependency>
  </dependencies>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-plugin-plugin</artifactId>
        <version>${project.version}</version>
        <executions>
          <!-- if you want to generate help goal -->
          <execution>
            <id>help-goal</id>
            <goals>
              <goal>helpmojo</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  ...
  </build>
  ...
</project>
+-----+
