If your expertise is in Java as you say. You should have a look at Play Framework - it's a web framework inspired by Ruby on Rails with a very short development cycle - just save your Java source file and update your web browser. And if you want to try another language, Play Framework has a module that let you use Scala instead.
I like Play Framework since it's easy to understand and has good performance. You can also use JPA and Hibernate for the ORM-layer if you want.
