Fetching Maven artifacts programmatically [closed]

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I'm looking for a Java API which can be used to retreive Maven artifacts from a remote repository. I've found Eclipse Ather so far but it looks over complicated for my needs so i'm seeking for something more simple.

What i need is:

• I have to specify the location of the remote Maven repository
• I like to fetch an artifact based on it's groupId + artifactId + version
• The API have to provide the current remote version of the artifact (think about SNAPSHOT artifacts which are regularly built so they have a generated part in their versions)
• Return the location of the artifact, a HTTP URL is preferred (i'll fetch it on my own with eg. Apache HTTP Client)
• Optionally retreive the artifact's which are the dependants of the requested one.

Answer 1

jcabi-aether may help you (I'm a developer). It's a simple wrapper around Aether, that lets you find all transitive dependencies of a Maven artifact:

File repo = this.session.getLocalRepository().getBasedir();
Collection<Artifact> deps = new Aether(this.getProject(), repo).resolve(
  new DefaultArtifact("junit", "junit-dep", "", "jar", "4.10"),
  JavaScopes.RUNTIME
);

Thus, all you need to provide as an input is:

• Local repo location, as a directory name
• List of repote repositories (MavenProject#getRemoteRepositories())
• Maven coordinates of the artifact
• Maven scope to look for

Absolute paths of every dependency found can be obtained as Artifact#getPath()

Answer 2

    public List<Artifact> findDependencies(Artifact artifact) throws DependencyCollectionException {

    CollectRequest collectRequest = new CollectRequest();
    collectRequest.setRoot( new Dependency(artifact, "" ) );
    collectRequest.addRepository(repository);

    final MavenServiceLocator locator = new MavenServiceLocator();
    locator.addService( RepositoryConnectorFactory.class, FileRepositoryConnectorFactory.class );
    locator.addService( RepositoryConnectorFactory.class, WagonRepositoryConnectorFactory.class );
    locator.setServices( WagonProvider.class, new WagonProvider() {
        public Wagon lookup(String roleHint) throws Exception {
            if (Arrays.asList("http", "https").contains(roleHint)) {
                return new LightweightHttpWagon();
            }
            return null;
        }

        public void release(Wagon wagon) {

        }
    });

    final RepositorySystem system = locator.getService(RepositorySystem.class);
    MavenRepositorySystemSession session = new MavenRepositorySystemSession();

    session.setLocalRepositoryManager( system.newLocalRepositoryManager(localRepository) );
    session.setTransferListener( new LoggingTransferListener() );
    session.setRepositoryListener( new LoggingRepositoryListener() );

    final List<Artifact> artifacts = new ArrayList<Artifact>();

    system.collectDependencies(session, collectRequest).getRoot().accept( new DependencyVisitor() {
        public boolean visitEnter(DependencyNode dependencyNode) {
            artifacts.add(dependencyNode.getDependency().getArtifact());
            return true;
        }

        public boolean visitLeave(DependencyNode dependencyNode) {
            return true;
        }
    });
    return artifacts;
}

Answer 3

Aether jest actually pretty simple and elegant way of doing this. It's one of major enhancements in Maven 3 and many was looking for it. Look at this for some initial code to work with. I don't remember a method to get exact URL of the artifact, but other requirements are supported AFAIR.

Answer 4

Have you tried using Apache Ivy? It supports fetching maven dependencies.

The documentation for this use case is a little bit sparse, but I found some information on programmatic use of Ivy here.