[Spring project] JPA

JPA

---

1. build.gradle 파일에 jpa, h2 관련 라이브러리 추가

 

implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
runtimeOnly 'com.h2database:h2'

 

 

2. application.properties 수정

spring.datasource.url=jdbc:h2:tcp://localhost/~/test
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.username=sa
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=none

=> jpa가 만드는 sql을 볼 수 있다.

  하이버네이트가 객체를 보고 테이블을 자동으로 생성해주는 기능도 있다. 테이블은 이미 생성했으므로 옵션을 끈다. 

 

3. domain/member 에 Entity 관련 어노테이션 추가

 

package hello.hello_spring.domain;

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;

@Entity
public class Member {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

 

 

4. JpaMemberRepository

package hello.hello_spring.repository;

import hello.hello_spring.domain.Member;

import jakarta.persistence.EntityManager;
import jakarta.transaction.Transactional;

import java.util.List;
import java.util.Optional;


public class JpaMemberRepository implements MemberRepository {

    private final EntityManager em;

    public JpaMemberRepository(EntityManager em) {
        this.em = em;
    }


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

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

    @Override
    public Optional<Member> findByName(String name) {
        List<Member> result = em.createQuery("select m from Member m where m.name = :name", Member.class)
                .setParameter("name", name)
                .getResultList();
        return result.stream().findAny();
    }

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

    }
}

 

 

5. MemberService에 @Transactional 어노테이션 추가

 

6. SpringConfig 파일 수정

package hello.hello_spring;

import hello.hello_spring.domain.Member;
import hello.hello_spring.repository.JpaMemberRepository;
import hello.hello_spring.repository.MemberRepository;
import hello.hello_spring.repository.MemoryMemberRepository;
import hello.hello_spring.service.MemberService;
import jakarta.persistence.EntityManager;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
import java.util.List;
import java.util.Optional;

@Configuration
public class SpringConfig {

    private EntityManager em;
    
    @Autowired
    public SpringConfig(EntityManager em) {
        this.em = em;
    }
    
    @Bean
    public MemberService memberService() {
        return new MemberService(memberRepository());
    }

    @Bean
    public MemberRepository memberRepository() {
        return new JpaMemberRepository();
    }
}

 

 

6. 테스트