JpaInjectionServicesImpl.java 文件源码

private synchronized EntityManager getEntityManager(final PersistenceUnitInfo unit) {
    if (entityManagers.containsKey(unit.getPersistenceUnitName())) {
        return entityManagers.get(unit.getPersistenceUnitName());
    }
    final String providerClassName = unit.getPersistenceProviderClassName();
    try {
        final PersistenceProvider provider = (PersistenceProvider) Class.forName(providerClassName).newInstance();
        final EntityManagerFactory emf = provider.createContainerEntityManagerFactory(unit, new HashMap());
        final EntityManager entityManager = emf.createEntityManager();
        entityManagers.put(unit.getPersistenceUnitName(), entityManager);
        entityManager.getTransaction().begin();
        return entityManager;
    } catch (final IllegalAccessException | InstantiationException | ClassNotFoundException e) {
        throw new TestEEfiException("Failed to load persistence provider class " + providerClassName, e);
    }
}