public static EntityManager getEntityManager() {
		if (entityManagerFactory == null) {
			entityManagerFactory =
					Persistence.createEntityManagerFactory(
							PERSISTENCE_UNIT);
		}
		EntityManager entityManager = threadEntityManager.get();
		if (entityManager == null || !entityManager.isOpen()) {
			entityManager =
					entityManagerFactory.createEntityManager();
			JpaUtil.threadEntityManager.set(entityManager);
		}
		return entityManager;
	}