Question

I’d like to call Maven goals from within a plugin and am reluctant to accept the cost of forking a process as the initialisation. Is there any way of doing this?

Answer 1

I doubt this is a supported approach but it worked for me.

/**
 * @parameter expression="${session}"
 * @required
 * @readonly
 */
 private MavenSession session;

/**
 * @component
 * @readonly
 */
 private Maven maven;
/**
 * @parameter default-value="${project.remoteArtifactRepositories}"
 * @readonly
 **/
protected List<ArtifactRepository> remoteArtifactRepositories;
/**
 * The project's remote repositories to use for the resolution of plugins
 * and their dependencies.
 * 
 * @parameter default-value="${project.pluginArtifactRepositories}"
 * @readonly
 */
private List<ArtifactRepository> pluginArtifactRepositories;
/**
 * @parameter default-value="${localRepository}"
 * @readonly
 * */
private ArtifactRepository localRepository;

…

List<String> goals = ...
File pomFile = ...
MavenExecutionRequest req = new DefaultMavenExecutionRequest();
req.setPom(pomFile);
req.setBaseDirectory(pomFile.getParentFile());
req.setGoals(goals);
req.setProxies(session.getSettings().getProxies());
req.setMirrors(session.getSettings().getMirrors());
req.setLocalRepository(localRepository);
req.setRemoteRepositories(remoteArtifactRepositories);
req.setPluginArtifactRepositories(pluginArtifactRepositories);
MavenExecutionResult result = session.execute(req);

To introspect the processing, you can subclass AbstractExecutionListener and use req.setExecutionListener() to apply it.