JPA and PostgreSQL
I'm on a project that uses the EclipseLink implementation of JPA to talk to a PostgreSQL database. I have a task for which PostgreSQL NOTIFY/LISTEN seems like a perfect fit. Unfortunately, I'm a JPA newb, and am struggling to figure out how to make it work. So I guess I really have two questions; answering either one will make me happy.
1) What's the best way for me to get a hold o开发者_如何学Pythonf the direct JDBC connection to the database? (Which I sincerely hope will prove to be of type org.postgresql.PGConnection
.)
OR
2) What's the best way for me to emulate/access org.postgresql.PGConnection.getNotifications()
via EclipseLink JPA?
Thank you very much for your help.
Edit: Two working solutions! I love this site. If anybody has anything to say about hidden gotchas/benefits that would make either Pascal's or Balus's solution better than the other before I hand out the checkmark, I'd like to hear it.
Getting a JDBC connection from an EntityManager
in EclipseLink is answered in the EclipseLink wiki.
The way differs per JPA API version. Here's an extract from the wiki:
JPA 2.0
entityManager.getTransaction().begin();
java.sql.Connection connection = entityManager.unwrap(java.sql.Connection.class);
...
entityManager.getTransaction().commit();
JPA 1.0
entityManager.getTransaction().begin();
UnitOfWorkImpl unitOfWork = (UnitOfWorkImpl)((JpaEntityManager)entityManager.getDelegate()).getActiveSession();
unitOfWork.beginEarlyTransaction();
java.sql.Connection connection = unitOfWork.getAccessor().getConnection();
...
entityManager.getTransaction().commit();
You should be able to get it from org.eclipse.persistence.internal.jpa.EntityManagerImpl
that is returned by EntityManager.getDelegate()
:
java.sql.Connection conn = ((EntityManagerImpl)(em.getDelegate())).getServerSession().getAccessor().getConnection();
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