java - Maven - how to include empty directories

Question

By default during the build process maven is removing the empty directories.
Do you know if a parameter can be specified in the pom to instruct maven to include empty directories in the generated target/test-classes folder?

Answer 1

According to this ticket MRESOURCES-36, there should be a <includeEmptyDirs> element, but only for Maven Resources Plugin 2.3.

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-resources-plugin</artifactId>
  <version>2.3</version>
  <configuration>
    <includeEmptyDirs>true</includeEmptyDirs>
  </configuration>
</plugin>

---

For Maven versions which included an older version of the Resources plugin:

Until this issue is fixed, here is a workaround I've been using successfully.
Add this plugin element into project/build/plugins in your pom.xml, and change the dir in the mkdir task.

You can have multiple <mkdir> elements for multiple directories. The mkdir task does nothing if the directory has already been copied by the resources plugin.

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-antrun-plugin</artifactId>
  <executions>
    <execution>
      <id>create-empty-directory</id>
      <phase>process-classes</phase>
      <goals>
        <goal>run</goal>
      </goals>
      <configuration>
        <tasks>
          <mkdir dir="${basedir}/target/classes/empty" />
        </tasks>
      </configuration>
    </execution>
  </executions>
</plugin>

This originally came from the openejb-standalone pom.xml in the openejb project.