I had to learn Spring and Hibernate. Spring had good documentation that you can read on an ereader. It's also very mature, so there's lots of help on Stackover

I had to learn Spring and Hibernate. Spring had good documentation that you can read on an ereader. It's also very mature, so there's lots of help on Stackoverflow. Hibernate was a bit more difficult, but Vlad Mihalcea has improved the documentation side a lot. Hibernate also allows you to drop down to native queries, which coupled with Spring Data's "projections" are useful.