Question

I have pom.xml with the structure like:

<plugins>
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>2.5</version>
    <configuration>
        <includes>
                 ... some directories with .java files to compile.

…

<plugin>  --- some my plugin that generates one more dir with .java files.

At this point I want to compile the newly generated files, so I repeat here step 1 with different content of “includes” element. Second compilation does not happen at all. Please advice.

Answer 1

Your plugin should run in generate-sources phase. Then you have to make sure that the generated source is available during the normal compile phase.

Your plugin should be configured something like this:

<build>
    <plugins>
        <plugin>
            <groupId>your.group</groupId>
            <artifactId>your-generator-plugin</artifactId>
            <version>your-generator-version</version>
            <executions>
                <execution>
                    <phase>generate-sources</phase>
                    <goals>
                        <goal>your-generator-goal</goal>
                    </goals>
                    <configuration>
                        <!-- Here goes all the plugin configuration -->
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

You can directly from your plugin (mojo) add the compilation source path to use.

Here is an example of what you must add to your mojo:

/**
 * The current project representation.
 * @parameter expression="${project}"
 * @required
 * @readonly
 */
private MavenProject project;

/**
 * Directory wherein generated source will be put; main, test, site, ... will be added implictly.
 * @parameter expression="${outputDir}" default-value="${project.build.directory}/src-generated"
 * @required
 */
private File outputDir;

And something like this must be added to your execute() method:

if (!settings.isInteractiveMode()) {
    LOG.info("Adding " + outputDir.getAbsolutePath() + " to compile source root");
}
project.addCompileSourceRoot(outputDir.getAbsolutePath());

---

This will output the generated java source files into target/src-generated/ but that can either be changed to some other default value in your mojo OR by adding this to the configuration part of the plugin:

<outputDir>path/to/my/generated/source/</outputDir>

---

The generated java source files will automatically be included in the compile phase.