h2. Using the openjpa-maven-plugin

The Maven plugin, formerly provided by the Codehaus project is now part of OpenJPA 2.2.0. The plugins documentation can be found [here|http://people.apache.org/~mikedd/openjpa/openjpa-maven-plugin/] until it finds a permanent home one the openjpa site. 

The previous versions of the plugin can be found at the [Codehaus project|http://mojo.codehaus.org/openjpa-maven-plugin/index.html]

For example, to enhance you source entity classes after they have been compiled (but exclude any POJO classes that rely upon orm.xml maappings), add the openjpa-maven-plugin to the <build> section of your pom.xml, like -
{code}
    <build>
        ...
        <plugin>
            <groupId>org.apache.openjpa</groupId>
            <artifactId>openjpa-maven-plugin</artifactId>
            <version>2.2.0-SNAPSHOT</version>
            <configuration>
                <includes>**/entities/*.class</includes>
                <excludes>**/entities/XML*.class</excludes>
                <addDefaultConstructor>true</addDefaultConstructor>
                <enforcePropertyRestrictions>true</enforcePropertyRestrictions>
            </configuration>
            <executions>
                <execution>
                    <id>enhancer</id>
                    <phase>process-classes</phase>
                    <goals>
                        <goal>enhance</goal>
                    </goals>
                </execution>
            </executions>
            <dependencies>
                <dependency>
                    <groupId>org.apache.openjpa</groupId>
                    <artifactId>openjpa</artifactId>
                    <!-- set the version to be the same as the level in your runtime -->
                    <version>1.2.2</version>
                </dependency>
            </dependencies>
        </plugin>
        ...
    </build>
{code}

There are other goals available to create the Entity to SQL mapping and Entity to XML Schema mapping, which are documented under the [Goals section|http://mojo.codehaus.org/openjpa-maven-plugin/plugin-info.html] on the plugin website.

h2. Using the maven-antrun-plugin

You can use the maven-antrun-plugin to launch the OpenJPA enhancer task using ANT.  The steps are nearly identical to the ones for [Enhancing with ANT] (again, you may not need to move the persistence.xml file to the build directory, but I did for this write-up).

{code}
      <build>
      <!-- Copy the persistence.xml file to the build dir -->
      <!-- You can skip this step if you put the persistence.xml in src/main/resources/META-INF instead of src/main/java/META-INF -->
      <resources>
          <resource>
            <directory> src/main/java </directory>
            <includes>
              <include> **/*.xml </include>
              </includes>
          </resource>
        </resources>
        <plugins>
    .....           
          <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-antrun-plugin</artifactId>
            <version>1.2</version>
            <executions>
              <execution>
                  <phase>process-classes</phase>
                <configuration>
                  <tasks>
                      <taskdef name="openjpac" classname="org.apache.openjpa.ant.PCEnhancerTask" classpathref="maven.compile.classpath"/>
                      <openjpac>
                          <classpath refid="maven.compile.classpath"/>
                      </openjpac>
                  </tasks>
                </configuration>
                <goals>
                  <goal>run</goal>
                </goals>
              </execution>
            </executions>
          </plugin>
        </plugins>
    ....
      </build>
{code}