The WEB4J tool is likely worth a look.
It has a much smaller number of classes in comparison with other tools. It is "full stack", so it helps you build all parts of your web app. Thus, you don't have to learn several different tools - just one.
A college instructor related to me that he felt it was "almost perfect" for his students, since it was at just the right level, and didn't hide things behind complicated abstractions - it was plain to see how all the parts worked together.
