실무 활용 - 순수 JPA와 Querydsl

순수 JPA 리포지토리와 Querydsl

 

순수 JPA 리포지토리

@Repository
public class MemberJpaRepository {
 private final EntityManager em;
 private final JPAQueryFactory queryFactory;
 
 public MemberJpaRepository(EntityManager em) {
 this.em = em;
 this.queryFactory = new JPAQueryFactory(em);
 }
 
 public void save(Member member) {
 em.persist(member);
 }
 
 public Optional<Member> findById(Long id) {
 Member findMember = em.find(Member.class, id);
 return Optional.ofNullable(findMember);
 }
 
 public List<Member> findAll() {
 return em.createQuery("select m from Member m", Member.class)
 .getResultList();
 }
 
 public List<Member> findByUsername(String username) {
 return em.createQuery("select m from Member m where m.username = :username", Member.class)
 .setParameter("username", username)
 .getResultList();
 }
 
}

 

 

순수 JPA 리포지토리 테스트

@SpringBootTest
@Transactional
class MemberJpaRepositoryTest {
 @Autowired
 EntityManager em;
 @Autowired
 MemberJpaRepository memberJpaRepository;
 
 @Test
 public void basicTest() {
 Member member = new Member("member1", 10); memberJpaRepository.save(member);
 Member findMember = memberJpaRepository.findById(member.getId()).get();
 assertThat(findMember).isEqualTo(member);
 
 List<Member> result1 = memberJpaRepository.findAll();
 assertThat(result1).containsExactly(member);
 
 List<Member> result2 = memberJpaRepository.findByUsername("member1");
 assertThat(result2).containsExactly(member);
 }

Querydsl 사용

 

public List<Member> findAll_Querydsl() {
 return queryFactory
 .selectFrom(member).fetch();
 }
 
 public List<Member> findByUsername_Querydsl(String username) {
 return queryFactory
 .selectFrom(member)
 .where(member.username.eq(username))
 .fetch();
 }

 

Querydsl 테스트 추가

@Test
public void basicQuerydslTest() {
 Member member = new Member("member1", 10);
 memberJpaRepository.save(member); Member findMember = memberJpaRepository.findById(member.getId()).get();
 assertThat(findMember).isEqualTo(member);
 
 List<Member> result1 = memberJpaRepository.findAll_Querydsl();
 assertThat(result1).containsExactly(member);
 
 List<Member> result2 = memberJpaRepository.findByUsername_Querydsl("member1");
 assertThat(result2).containsExactly(member);
}

 

JPAQueryFactory 스프링 빈 등록
다음과 같이 JPAQueryFactory 를 스프링 빈으로 등록해서 주입받아 사용해도 된다.

@Bean
JPAQueryFactory jpaQueryFactory(EntityManager em) {
return new JPAQueryFactory(em);
}

 

참고: 동시성 문제는 걱정하지 않아도 된다. 왜냐하면 여기서 스프링이 주입해주는 엔티티 매니저는 실제 동작 시점에 진짜 엔티티 매니저를 찾아주는 프록시용 가짜 엔티티 매니저이다. 이 가짜 엔티티 매니저는 실제 사용 시점에 트랜잭션 단위로 실제 엔티티 매니저(영속성 컨텍스트)를 할당해준다. > 더 자세한 내용은 자바 ORM 표준 JPA 책 13.1 트랜잭션 범위의 영속성 컨텍스트를 참고하자.

 

 

 

 

출처 : 김영한 JPA 스프링 데이터 강의