Hello,

I have three tables, for instance user (id, name), category (id, name) and entity_category (entity_id, entity_type, category_id). How to do join them in annotation to get Category JPA object in User JPA (I need join by constant entity_type and user id) and have possibility to save relations to entity_category table when I save User JPA?

Code works, but entity_type isn't saved when I save user JPA object.
If possible to solve it using Hibernate 4?

Yes, you can! But not with JPA, with the Hibernate @Any annotation.

Your mapping will become something like this: