It depends. When you say "Java" do you mean Java or the JVM? It's certainly not anything like rails, but if I'm forced to work in Java I'm quite fond of Spring

It depends. When you say "Java" do you mean Java or the JVM? It's certainly not anything like rails, but if I'm forced to work in Java I'm quite fond of SpringMVC, especially for building restful services that need to support a bunch of different serialization formats. Once you get over the fact that Spring-done-right is a bit XML-heavy, it's quite good. Also since most of the heavy-lifting is front-loaded into the the context initialization it can be very performant. Otherwise for more simple stuff I just drop down to straight-up servlets and JSP. If you can relax your requirement to just the JVM there are tons and tons of options...