Hibernate EntityManager, is it supposed to be used as a singleton?

Question

I am not using Spring so I am creating an instance of EntityManager within a class.

I used Hibernate-Eclipse reverse engineering to auto-generate the classes. These

Answer 1

You need a dependency injection framework like Spring or Google Guice to inject objects into your class otherwise it may not be injected automatically for you.

Basically this is an annotation provided by JPA which will work with in tandem with hibernate or any other ORM framework per say but you need a DI framework to inject the objects.

Regarding the single instance of entity manager i don't think you need that if you go by Spring since it takes care of managing the instances and the transactions for you by tying your entity manager with the jpa transaction.