There are numerous ways to integrate and build RESTfull web services in Java, Bill de hÓra takes a look at three server-side Java projects which can aid you in the process.
RESTFaces
Sadly, there isn’t very much that is “RESTful” about RESTFaces."
Unfortunately, I have to agree. REST is becoming something of a buzzword these days and I suspect RESTfaces might be suffering from that instead of focusing on what it actually does, which is provided a patch for JSF to allow CGI style links
Struts2 REST
On a more positive note, Stefan Tilkov links to some material about REST support in Struts2; it looks like someone did some digging into the Web's design. Check it out.
SpringMVC + Restlet
Personally, I think unifying SpringMVC, RESTlet routers and JSR311 annotations would give you most of what you need.
"So how does Spring 2.5's annotation-based controller approach fit into this picture? Quite simple: It is essentially an alternative controller type supported by the DispatcherServlet / DispatcherPortlet, not implementing a specific interface but rather using annotations to express request mappings for specific handler methods. It is primarily a next-generation style for implementing multi-action controllers, superseding Spring's good old MultiActionController class"
Read Bill de hÓra's complete post:
http://www.dehora.net/journal/2007/11/19/java-rest/