EntityManager handling

Question

I am new to JPA 2 and I want to find out which are the best practices for handling an EntityManager on RESOURCE_LOCAL and with JTA. From what I have read, I should be able to make a dependency injection, but I do not quite understand how.

I am using EclipseLink as an implementation.

Answer 1

To obtain a reference to EntityManager in your bean, use the following annotation:

@PersistenceContext
private EntityManager entityManager;

Or if you are not using EJB:

EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("myPersistenceUnitName");
EntityManager entityManager = entityManagerFactory.createEntityManager();
//Do some work...
entityManager.close();
entityManagerFactory.close();

See Persistence unit as RESOURCE_LOCAL or JTA? for an explanation of RESOURCE_LOCAL vs JTA.