@Repository public class MemberJpaRepository { ..... public void save(Member member){ em.persist(member); } public Optional findById(Long id){ Member findMember = em.find(Member.class, id); return Optional.ofNullable(findMember); } public List findAll(){ return em.createQuery("select m from Member m", Member.class) .getResultList(); } public List findByUsername(String username){ return em.create..