How to configure EntityManager in jersey / hk2 app?

Question

I have a jersey-2 / hk2 app that uses JPA persistence. EntityManager bound at startup like this

 public MyApplication() { // ... register(new AbstractBinder() { @Override public void configure() { bindFactory(EmFactory.class) .to(EntityManager.class) .in(RequestScoped.class); } }); } 

with factory class being

 public class EmFactory implements Factory<EntityManager> { private static final String PERSISTENCE_UNIT = "unit"; private EntityManagerFactory emf; private CloseableService closeableService; @Inject public EmFactory(@Named(PERSISTENCE_UNIT) String persistenceUnit, CloseableService closeableService) { emf = Persistence.createEntityManagerFactory(persistenceUnit); this.closeableService = closeableService; } @Override public EntityManager provide() { final EntityManager entityManager = emf.createEntityManager(); closeableService.add(new Closeable() { @Override public void close() throws IOException { if(entityManager.isOpen()) { entityManager.close(); } } }); return entityManager; } @Override public void dispose(EntityManager entityManager) { if(entityManager.isOpen()) { entityManager.close(); } } } 

this works, but then for each request I get a warning in the logs about the already registered EntityManager:

 HHH000436: Entity manager factory name (unit) is already registered. \ If entity manager will be clustered or passivated, specify a unique \ value for property 'hibernate.ejb.entitymanager_factory_name' 

What am I doing wrong? What is the correct way to initialize EntityManager in jersey-2 / hk2 app?

Answer 1

One option is that instead of creating a new EntityManagerFactory in EMFactory (which is in the request area), you can create a singleton factory for EntityManagerFactory , and then just enter EntityManagerFactory in EMFactory .

 public class EMFFactory implements Factory<EntityManagerFactory> { private final EntityManagerFactory emf; public EMFFactory (){ emf = Persistence.createEntityManagerFactory(persistenceUnit); } public EntityManagerFactory provide() { return emf; } ... } public class EMFactory implements Factory<EntityManager> { private final EntityManager em; @Inject public EMFactory (EntityManagerFactory emf){ em = emf.createEntityManager(); } public EntityManager provide() { return em; } ... } 

We have not tested this exact implementation, but it should look something like this. I have used this template before.

 register(new AbstractBinder() { @Override public void configure() { bindFactory(EMFFactory.class).to(EntityManagerFactory.class).in(Singleton.class); bindFactory(EMFactory.class).to(EntityManager.class).in(RequestScoped.class); } }); 

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UPDATE

One comment on the above example is that it does not clear resources, i.e. EntityManager should be close; it will not close. There is a dispose method in the Factory class that we need to override, but from my experience it is never called Jersey.

What we can do is add an EntityManager to [ CloseableService ] [1]

 public class EMFactory implements Factory<EntityManager> { private final EntityManagerFactory emf; private final CloseableService closeService; @Inject public EMFactory (EntityManagerFactory emf, CloseableService closeService){ this.emf = emf; this.closeService = closeService; } public EntityManager provide() { final EntityManager em = emf.createEntityManager(); this.closeService.add(new Closeable(){ @Override public void close() { em.close(); } }); return em; } ... } 

Thus, the EntityManager will be closed at the end of the request.