[ Spring-Boot ] Data - JPA 사용하기

DB는 H2 DB를 사용하였습니다. 관련 설정이나 설치방법은 제외하겠습니다.

 

테스트에 사용할 엔티티를 생성 

@Entity
@Getter @Setter
@NoArgsConstructor(access = AccessLevel.PROTECTED) // 기본생성자를 만들어 주는 기능
public class Member extends BaseEntity{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "member_id")
    private Long Id;
    private String username;
    private int age;

    @ManyToOne(fetch = LAZY)
    @JoinColumn(name = "team1_id")
    private Team team;


    public Member( String username) {
        this.username = username;
    }

    public Member(String username, int age, Team team) {
        this.username = username;
        this.age = age;
        if(team != null){
            changeTeam(team);
        }
    }

    public Member(String username, int age) {
        this.username = username;
        this.age = age;
    }

    public void changeTeam(Team team) {
        this.team = team;
        team.getMembers().add(this);
    }
}

 

 

Repository로 사용할 인터페이스를 생성하여 준다. 

// Data JPA 사용시 "JpaRepository<엔티티,엔티티의 키값>" 상속받아 사용한다.  
public interface MemberRepository extends JpaRepository<Member,Long> ,MemberRepositoryCustom{


}

 

인터페이스에서 상속받은 JpaRepository를 살펴보면 아래처럼 기본적으로 JPA에서 제공하는 기능들을 사용할 수 있다.

 

/*
 * Copyright 2008-2021 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.data.jpa.repository;

import java.util.List;

import javax.persistence.EntityManager;

import org.springframework.data.domain.Example;
import org.springframework.data.domain.Sort;
import org.springframework.data.repository.NoRepositoryBean;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.data.repository.query.QueryByExampleExecutor;

/**
 * JPA specific extension of {@link org.springframework.data.repository.Repository}.
 *
 * @author Oliver Gierke
 * @author Christoph Strobl
 * @author Mark Paluch
 */
@NoRepositoryBean
public interface JpaRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.CrudRepository#findAll()
	 */
	@Override
	List<T> findAll();

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.PagingAndSortingRepository#findAll(org.springframework.data.domain.Sort)
	 */
	@Override
	List<T> findAll(Sort sort);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.CrudRepository#findAll(java.lang.Iterable)
	 */
	@Override
	List<T> findAllById(Iterable<ID> ids);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.CrudRepository#save(java.lang.Iterable)
	 */
	@Override
	<S extends T> List<S> saveAll(Iterable<S> entities);

	/**
	 * Flushes all pending changes to the database.
	 */
	void flush();

	/**
	 * Saves an entity and flushes changes instantly.
	 *
	 * @param entity
	 * @return the saved entity
	 */
	<S extends T> S saveAndFlush(S entity);

	/**
	 * Deletes the given entities in a batch which means it will create a single {@link Query}. Assume that we will clear
	 * the {@link javax.persistence.EntityManager} after the call.
	 *
	 * @param entities
	 */
	void deleteInBatch(Iterable<T> entities);

	/**
	 * Deletes all entities in a batch call.
	 */
	void deleteAllInBatch();

	/**
	 * Returns a reference to the entity with the given identifier. Depending on how the JPA persistence provider is
	 * implemented this is very likely to always return an instance and throw an
	 * {@link javax.persistence.EntityNotFoundException} on first access. Some of them will reject invalid identifiers
	 * immediately.
	 *
	 * @param id must not be {@literal null}.
	 * @return a reference to the entity with the given identifier.
	 * @see EntityManager#getReference(Class, Object) for details on when an exception is thrown.
	 */
	T getOne(ID id);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.query.QueryByExampleExecutor#findAll(org.springframework.data.domain.Example)
	 */
	@Override
	<S extends T> List<S> findAll(Example<S> example);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.repository.query.QueryByExampleExecutor#findAll(org.springframework.data.domain.Example, org.springframework.data.domain.Sort)
	 */
	@Override
	<S extends T> List<S> findAll(Example<S> example, Sort sort);
}

 

 

Data JPA 관련 문서 

https://spring.io/projects/spring-data-jpa#learn

Spring Data JPA

 

마지막으로 테스트 클래스를 생성한 뒤 확인

 

@SpringBootTest
@Transactional
class MemberJpaRepositoryTest {

    @Autowired
    MemberJpaRepository memberJpaRepository;

    @Test
    public void testMember() {
        Member member = new Member("memberA");
        //Member 객체 저장  
        Member savedMember = memberJpaRepository.save(member);
        //Member 객체 조회
        Member findMember = memberJpaRepository.find(savedMember.getId());
         
        //검증 
        assertThat(findMember.getId()).isEqualTo(member.getId());
        assertThat(findMember.getUsername()).isEqualTo(member.getUsername());
        //영속성 컨텍스트 에서 가져오기 때문에 같은 객체로 가져온다.
        assertThat(findMember).isEqualTo(member);
    }