PersistenceUnit vs PersistenceContext

java jakarta-ee jpa persistence entitymanager
user2377971 picture user2377971 · Jan 10, 2014 · Viewed 29k times · Source

In few project I have been successfully using 

@PersistenceUnit(unitName = "MiddlewareJPA")
EntityManagerFactory emf;
...
EntityManager entityManager = emf.createEntityManager();

to obtain EntityManager for Database connection, but some days ago I was trying to move my project to Jboss EAP 6.2 and it couldn't create EntityManager. I was googling it and I found that I should try change @PersistenceUnit to

@PersistenceContext(unitName = "MiddlewareJPA")
private EntityManager entityManager;

to obtain EntityManager. It worked but I don't know why. What is the difference bettween PersistenceUnit and PersistenceContext? What are pros and cons of each one? Where should we be using one of them?

Answer

chrylis -cautiouslyoptimistic- picture chrylis -cautiouslyoptimistic- · Jan 10, 2014

PersistenceUnit injects an EntityManagerFactory, and PersistenceContext injects an EntityManager. It's generally better to use PersistenceContext unless you really need to manage the EntityManager lifecycle manually.

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