I'm thinking if i use maps like Map<String,List<Entity>> or Map<Long,List<Entity>> it will help me with a few things, but I couldn't find any example to map that kind of map.
My question is, is it possible to do that kind of mapping in JPA standards, and what kind of annotation I should use?
Yes, it's possible to create either of those Maps. Why not try it and answer your own question? It would be faster than passively asking here.
As for JPA, I would suggest a better abstraction than a Map for holding onto that data. This feels too generic for me. That might be what you're going for, but JPA ORM ought to map to a more robust object model than collections.
来源：https://stackoverflow.com/questions/9784101/is-it-possible-to-map-a-mapstring-listentity-in-jpa