Pattern for processing custom Java annotations

I have read a lot of tutorials about Java annotations lately and I like the idea of creating a custom one. Most articles cover the very basic idea and fairly simple implementations. I'm missing a proper pattern to process my annotation, though.

Lets say I have a custom annotation @Foobar to initialize fields. I need to pass all classes that use this annotation to my processor, let's call it FoobarProcessor:

public class AnnotatedClass {
  @Foobar
  private String test = "";

  static {
    FoobarProcessor.process(AnnotatedClass.class);
  }
}

Is there any approach to overcome this drawback? Is there any single point that all classes pass, where I can easily apply my annotation processor?