Exporting Maven properties from Ant code

Question

I've embedded the following code within my POM:

<plugin name="test">
  <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-antrun-plugin</artifactId>
      <executions>
        <execution>
          <phase>validate</phase>
            <configuration>
              <tasks>
                <pathconvert targetos="unix" property="project.build.directory.portable">
                  <path location="${project.build.directory}"/>
                </pathconvert>
              </tasks>
            </configuration>
          <goals>
        <goal>run</goal>
      </goals>
    </execution>
  </executions>
</plugin>

I then reference ${project.build.directory.portable} from the run project action but it comes back as null. Executing <echo> within the Ant block shows the correct value. What am I doing wrong?

Answer 1

For completeness, the mentioned feature was implemented in the maven-antrun-plugin in October 2010.

The configuration parameter you are looking for is exportAntProperties.

Example of use:

<plugin>
    <artifactId>maven-antrun-plugin</artifactId>
    <version>1.7-SNAPSHOT</version>
    <executions>
        <execution>
            <phase>process-resources</phase>
            <goals>
                <goal>run</goal>
            </goals>
            <configuration>
                <target>
                    <exec outputproperty="svnversion"
                        executable="svnversion">
                        <arg value=".." />
                    </exec>
                </target>
                <exportAntProperties>true</exportAntProperties>
            </configuration>
        </execution>
    </executions>
</plugin>

---

As a side note, at the time of this post (2011-10-20), the official plugin documentation didn't have this option documented. To get the help for 'versionXYZ' of the plugin:

mvn help:describe -Dplugin=org.apache.maven.plugins:maven-antrun-plugin:versionXYZ -Ddetail

Answer 2

The version 1.7 of the maven-antrun-plugin worked for me to pass a property from ant to maven (and from mvn to ant). Some sample code that calculates an md5 checksum of a file and later stores it into a property that is accessed by mvn at a later time:

<artifactId>maven-antrun-plugin</artifactId>
<version>1.7</version>
<executions>
    <execution>
        <id>ant-md5</id>
        <phase>initialize</phase>
        <goals>
        <goal>run</goal>
        </goals>
    <configuration>

<target>
    <property name="compile_classpath" refid="maven.compile.classpath"/>
    <property name="outputDir" value="${project.build.outputDirectory}"/>
    <property name="sourceDir" value="${project.build.sourceDirectory}"/>
    <checksum  file="${sourceDir}/com/blah/db/blah.java" property="blah.md5db"/>
</target>
<exportAntProperties>true</exportAntProperties>
</configuration>
</execution>
</executions>

The property is accessible in later with ${blah.md5db} in a java file.