how to create JPAQueryFactory correctly with QueryDsl

Question

I heard about EntityManager is not thread-safe , so we use @PersistenceContext instead of @Autowired .

However, I found about two ways to create JPAQueryFactory on the Internet.

1. define a bean like this

@Configuration
public class JPAQueryFactoryConfiguration {
    
    @Bean
    public JPAQueryFactory jpaQueryFactory(@Autowired EntityManager entityManager) {
        return new JPAQueryFactory(entityManager);
    }
}

2. @PersistenceContext on EntityManager,new JPAQueryFactory(entityManager) every time

@Service
public class TestServiceImpl implements TestService {
    @PersistenceContext
    private EntityManager entityManager;

    @Override
    public void test(){
        JPAQueryFactory jpaQueryFactory = new JPAQueryFactory(entityManager);
        xxxxxxxxxxxx
    }
}

I'm counfused. But, I think the first way is not correct according to the difference between @PersistenceContext and @Autowired

Answer 1

i am just biginer in EJB , type of JPAQueryFactory is Provider is not EntityManager , just Cast

JPAQueryFactory query = new JPAQueryFactory((Provider<EntityManager>) em);

or use the declaration of JPAQueryFactory

EntityManagerFactory emf = 
  Persistence.createEntityManagerFactory("com.baeldung.querydsl.intro");
EntityManager em = entityManagerFactory.createEntityManager();
JPAQueryFactory queryFactory = new JPAQueryFactory(em);

Answer 2

This article show how to use both entity manager and JPAQueryFactory: https://dzone.com/articles/spring-data-jpa-querydsl-taking-best-from-both-wor