As far as I see, what you really want to know is, if you're using JRebel with Eclipse, would you be able to see the changes instantly. So if I'm right about that, then JRebel will do the job you want.
With JRebel you can see all changes to Java code instantly in the browser. Save and refresh! The same is true for your other project files.
I've used it and it deploys your java file as soon as you save it, without even popping up some window which happens when you use build automatically in eclipse.