BuildLauncher

ProjectConnection connection = GradleConnector.newConnector()
   .forProjectDirectory(new File("some-folder"))
   .connect();

try {
   BuildLauncher build = connection.newBuild();

   //select tasks to run:
   build.forTasks("clean", "test");

   //include some build arguments:
   build.withArguments("-i", "--project-dir", "some-project-dir");

   //configure the standard input:
   build.setStandardInput(new ByteArrayInputStream("consume this!".getBytes()));

   //in case you want the build to use java different than default:
   build.setJavaHome(new File("/path/to/java"));

   //if your build needs crazy amounts of memory:
   build.setJvmArguments("-Xmx2048m", "-XX:MaxPermSize=512m");

   //if you want to listen to the progress events:
   ProgressListener listener = null; // use your implementation
   build.addProgressListener(listener);

   //kick the build off:
   build.run();
} finally {
   connection.close();
}