Comment Play framework is the way... (Score 2, Interesting) 253
Rails? Been there. Grails? Done that. Both are decent. Rails is very good, but the abuse of open classes gets old quickly. Grails is ok, but it's really just a thin veneer over a complex mix of Java projects, and God help you if you run into any problems, because you'll be dealing with a stack trace that's 1000s of lines long, and you be troubleshooting these underlying complex java libs.
For me, the play framework (http://www.playframework.org) is the best Rails-like approach on a Java platform. It stays very close to rails, so if you know rails learning it is easy. It's very pragmatic and very fast. It doesn't require a compile step to see your changes. It just works. Best of all, the code is clean and easy to troubleshoot. I suggest you check it out.