Java: What is the difference between @PersistenceContext and @Autowired?

@PersistenceContext — injects EntityManager. @Autowired — injects any Spring bean.

@PersistenceContext:

• Injects EntityManager.
• JPA-specific.
• Transaction-scoped.
• Manages persistence context lifecycle.

1@Stateless
2public class UserDao {
3    @PersistenceContext
4    private EntityManager em;
5
6    public User findById(Long id) {
7        return em.find(User.class, id);
8    }
9}

@Autowired:

• Injects Spring beans.
• Framework-agnostic.
• Constructor, field, setter injection.
• General-purpose injection.

1@Service
2public class UserService {
3    @Autowired
4    private UserRepository repo;
5}

How it works:

1. @PersistenceContext injects a transaction-scoped EntityManager.
2. @Autowired injects Spring-managed beans.
3. @PersistenceContext is JPA-specific.
4. @Autowired is framework-agnostic.

Key difference:

• @PersistenceContext — JPA EntityManager.
• @Autowired — Spring bean injection.

Best practice:

• Use @PersistenceContext for EntityManager injection.
• Use @Autowired for Spring beans.
• Prefer constructor injection over field injection.