German Gonzalez-Morris wrote:perhaps POJOs and EJBs was a better vocabulary to narrow down the question's context.
Anyway, about Spring/JPA and EJBs, I think we can discuss about it for long...
About the future I don't think it is worth caring about it at this moment, I guess if you learn Java you are not going to be working with it all your life, the important point is to get the concepts.
When it comes to the back-end, there are any number of choices. I'd recommend staying away from platform-prioprietary technologies (aka .Net) and focus on those that are multi-platform. That could be PHP, Ruby/Rails, or Java. Pick your poison.
If you want to learn Java, then the choice is obvious. If you want to get something off the ground quickly, PHP has a lower barrier to entry. If you want to land a job, either (or both) is a good choice.