순수 JPA 기반 리포지토리

MemberJpaRepository.java

@Repository
public class MemberJpaRepository {

    // 스프링 컨테이너가 JPA 영속성 컨텍스트인 엔티티 매니저를 가져온다.
    @PersistenceContext
    private EntityManager em;

    public Member save(Member member) {
        em.persist(member);
        return member;
    }

    public void delete(Member member) {
        em.remove(member);
    }

    public List<Member> findAll() {
        return em.createQuery("select m from Member m", Member.class)
                .getResultList();
    }

    public Optional<Member> findById(Long id) {
        Member member = em.find(Member.class, id);
        return Optional.ofNullable(member);
    }

    public long count() {
        return em.createQuery("select count(m) from Member m", Long.class)
                .getSingleResult();
    }

    public Member find(Long id) {
        return em.find(Member.class, id);
    }
}

TeamJpaRepository.java

@Repository
public class TeamJpaRepository {
    @PersistenceContext
    private EntityManager em;

    public Team save(Team team) {
        em.persist(team);
        return team;
    }

    public void delete(Team team) {
        em.remove(team);
    }

    public List<Team> findAll() {
        return em.createQuery("select t from Team t", Team.class)
                .getResultList();
    }

    public Optional<Team> findById(Long id) {
        Team team = em.find(Team.class, id);
        return Optional.ofNullable(team);
    }

    public long count() {
        return em.createQuery("select count(t) from Team t", Long.class)
                .getSingleResult();
    }
}

• JPQL을 이용해 쿼리를 만든다.

• 두 리포지토리가 비슷한 로직을 갖는다.

• update는 더티 체킹이 알아서 해주므로 따로 메서드가 없다.

TeamJpaRepositoryTest.java

@SpringBootTest
@Transactional
class TeamJpaRepositoryTest {

    @Autowired
    MemberJpaRepository memberJpaRepository;

    @Test
    public void testMember() {
        Member member = new Member("memberA");
        Member savedMember = memberJpaRepository.save(member);
        Member findMember = memberJpaRepository.find(savedMember.getId());

        assertThat(findMember.getId()).isEqualTo(member.getId());
        assertThat(findMember.getUsername()).isEqualTo(member.getUsername());
        assertThat(findMember).isEqualTo(member); // JPA 엔티티 동일성 보장
    }

    @Test
    public void basicCRUD() {
        Member member1 = new Member("member1");
        Member member2 = new Member("member2");

        memberJpaRepository.save(member1);
        memberJpaRepository.save(member2);

        // 단건 조회 검증
        Member findMember1 =
                memberJpaRepository.findById(member1.getId()).get();
        Member findMember2 =
                memberJpaRepository.findById(member2.getId()).get();

        assertThat(findMember1).isEqualTo(member1);
        assertThat(findMember2).isEqualTo(member2);

        // 리스트 조회 검증
        List<Member> all = memberJpaRepository.findAll();
        assertThat(all.size()).isEqualTo(2);

        // 카운트 검증
        long count = memberJpaRepository.count();
        assertThat(count).isEqualTo(2);

        // 삭제 검증
        memberJpaRepository.delete(member1);
        memberJpaRepository.delete(member2);

        long deletedCount = memberJpaRepository.count();
        assertThat(deletedCount).isEqualTo(0);
    }
}