Configuring staleness checking

By default, the Apt Maven Plugin only processes source files that are deemed to be stale. The definition of staleness depends on the relationship between the source files and the generated resources, which is determined by the annotation processor factory implementation used.

One-to-one factories

An annotation processor factory that generates a unique resource for each unique source file is called a one-to-one factory. It is assumed that one-to-one factories will generate a resource with the same name as the source file except with a different file extension. For example, a factory might generate a com/acme/Main.xml resource for the source file com/acme/Main.java.

To configure staleness checking for this type of factory, use the outputFileEndings configuration parameter as follows:

<project>
  ...
    <build>
      ...
      <plugins>
        ...
        <plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>apt-maven-plugin</artifactId>
          <version>1.0-alpha-4</version>
          <configuration>
            <outputFileEndings>
              <outputFileEnding>.xml</outputFileEnding>
            </outputFileEndings>
          </configuration>
        </plugin>
        ...
      </plugins>
      ...
    </build>
  ...
</project>

This tells the Apt Maven Plugin to only process a source file if its last modified timestamp is later than the last modified timestamp of its corresponding generated resource.

Many-to-one factories

An annotation processor factory that generates a single resource from all source files is called a many-to-one factory. For example, a factory might generate a persistence.xml resource after processing all source files.

To configure staleness checking for this type of factory, use the outputFiles configuration parameter as follows:

<project>
  ...
    <build>
      ...
      <plugins>
        ...
        <plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>apt-maven-plugin</artifactId>
          <version>1.0-alpha-4</version>
          <configuration>
            <outputFiles>
              <outputFile>persistence.xml</outputFile>
            </outputFiles>
          </configuration>
        </plugin>
        ...
      </plugins>
      ...
    </build>
  ...
</project>

This tells the Apt Maven Plugin to only process the source files if at least one source file has a last modified timestamp that is later than the last modified timestamp of the generated resource.

Disabling staleness checking

If the above scenarios are not compatible with your annotation processor factory then you may wish to disable staleness checking altogether. To disable staleness checking, use the force configuration parameter as follows:

<project>
  ...
    <build>
      ...
      <plugins>
        ...
        <plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>apt-maven-plugin</artifactId>
          <version>1.0-alpha-4</version>
          <configuration>
            <force>true</force>
          </configuration>
        </plugin>
        ...
      </plugins>
      ...
    </build>
  ...
</project>

This tells the Apt Maven Plugin to process all source files every time it is invoked.