[Spring] Spring Data JPA 사용 방법

pom.xml에 라이브러리 추가

<dependencies>
    <!-- Spring Boot JPA -->
    <dependency>
    	<groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>

    <!-- JPA 하이버네이트-->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>5.3.10.Final</version>
    </dependency>
    
    <!-- H2 데이터베이스 -->
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <version>1.4.199</version>
    </dependency>

</dependencies>

- H2: 인메모리 DB

 

 

테이블 매핑

@Entity(name = "member")
public class Member{

    @Id
    private Long id;
    private String name;

    @Builder
    public Member(String name){
        this.name = name;
    }
}

Member
(PK) bigint	id
varchar	name

- @Entity: JPA가 관리하는 클래스

> name: 속성 지정, 사용할 엔티티 이름 지정

 

- @Id: 데이터베이스 PK와 매칭

 

 

JPA Repository

@Repository
public interface SpringDataJpaRepository extends SpringDataJpaRepository<T, Long>{


    // 이름으로 조회
    List<T> findListByName(String name);
    
    // 직접 쿼리 설정
    @Query(value = "select c from Table c where c.name = name")
    List<T> findTableListByName(String name);

	...
}

 

JPA CRUD

public class JPATest {
	
	@Autowired
	SchoolRepository schoolRepository;

	@Test
	public void Insert() {
		School school = new School();
		school.setName("청아예술 고등학교");
		school.setRegion("서울");
		school.setRanking(1);
		
		schoolRepository.save(school); // Insert
		List<School> schools = schoolRepository.findAll(); // Select
        for(int i=0; i<schools.size(); i++) { 
			schools.get(i).setRegion("경기");
			schoolRepository.save(schools.get(i)); // Update
		}
        schoolRepository.deleteById(1); // Delete
		// schoolRepository.deleteAll(); // Delete All
	}
}