[2025 겨울방학 스프링 스터디] 정채은 #4주차

섹션 7 ..............

 

[ H2 데이터베이스 설치 ]

다운로드 on https://www.h2database.com 

실행 : h2.bat

데이터베이스 파일 생성 :  jdbc:h2:~/test

파일 생성 확인 : ~/test.mv.db

이후 접속 : jdbc:h2:tcp://localhost/~/test

 

 

테이블 생성하기

 

- sql/ddl.sql 파일 

drop table if exists member CASCADE;
create table member
(
	id bigint generated by default as identity,  
	name varchar(255),
	primary key (id)
);

 

- member 테이블 생성

drop table if exists member CASCADE;
create table member
(
	id bigint generated by default as identity,  
	name varchar(255),
	primary key (id)
);

 

- 실행 결과

 

 

오류 해결 방안

100.1.2.3  →  localhost

[ 순수 Jdbc ]

환경 설정

 

- build.gradle 파일에 추가

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

 

- resources/application.properties 에 추가

spring.datasource.url=jdbc:h2:tcp://localhost/~test
spring.datasource.diriver-class-name=org.h2.Driver
spring.datasource.username=sa

 

Jdbc 리포지토리 구현

 

- 구현 클래스 추가 이미지

- 스프링 설정 이미지

 

스프링의 DI 사용 → 기존 코드를 전혀 손대지 않고, 설정만으로 구현 클 래스를 변경

[ 스프링 통합 테스트 ]

회원 서비스 스프링 통합 테스트

package hello.hellospring.service;

import hello.hellospring.domain.Member;
import hello.hellospring.repository.MemberRepository;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.transaction.annotation.Transactional;
import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;
@SpringBootTest
@Transactional
class MemberServiceIntegrationTest {

  @Autowired MemberService memberService;
  @Autowired MemberRepository memberRepository;
 
  @Test
  public void 회원가입() throws Exception {
   
   //Given
     Member member = new Member();
     member.setName("hello");
 
   //When
     Long saveId = memberService.join(member);
 
   //Then
     Member findMember = memberRepository.findById(saveId).get();
     assertEquals(member.getName(), findMember.getName());
 }
 
 @Test
 public void 중복_회원_예외() throws Exception {
 
    //Given
    Member member1 = new Member();
    member1.setName("spring");
      
    Member member2 = new Member();
    member2.setName("spring");
    
    //When
    memberService.join(member1);
    IllegalStateException e = assertThrows(IllegalStateException.class,
            () -> memberService.join(member2));//예외가 발생해야 한다.
            
    assertThat(e.getMessage()).isEqualTo("이미 존재하는 회원입니다.");
  }
}

 

[ 스프링 JdbcTemplate ]

스프링 JdbcTemplate 회원 리포지토리

 

package hello.hellospring.repository;

import hello.hellospring.domain.Member;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
import org.springframework.jdbc.core.simple.SimpleJdbcInsert;

import javax.sql.DataSource;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;

public class JdbcTemplateMemberRepository implements MemberRepository {
 
 private final JdbcTemplate jdbcTemplate;
 
 public JdbcTemplateMemberRepository(DataSource dataSource) {
 jdbcTemplate = new JdbcTemplate(dataSource);
 }
 
 @Override
 public Member save(Member member) {
  SimpleJdbcInsert jdbcInsert = new SimpleJdbcInsert(jdbcTemplate);
  jdbcInsert.withTableName("member").usingGeneratedKeyColumns("id");
  
  Map<String, Object> parameters = new HashMap<>();
  parameters.put("name", member.getName());
  
  Number key = jdbcInsert.executeAndReturnKey(new  
MapSqlParameterSource(parameters));
  member.setId(key.longValue());
  return member;
 }

 @Override
 public Optional<Member> findById(Long id) {
  List<Member> result = jdbcTemplate.query("select * from member where id
= ?", memberRowMapper(), id);
  return result.stream().findAny();
 }

 

JdbcTemplate을 사용하도록 스프링 설정 변경

package hello.hellospring;

import hello.hellospring.repository.JdbcMemberRepository;
import hello.hellospring.repository.JdbcTemplateMemberRepository;
import hello.hellospring.repository.MemberRepository;
import hello.hellospring.repository.MemoryMemberRepository;
import hello.hellospring.service.MemberService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class SpringConfig {

    private DataSource dataSource;

    @Autowired
    public SpringConfig(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    // memberService를 스프링 빈으로 등록
    @Bean
    public MemberService memberService() {
        return new MemberService(memberRepository());
    }

    // memberRepository를 스프링 빈으로 등록
    @Bean
    public MemberRepository memberRepository() {
        //return new MemoryMemberRepository();
        return new JdbcTemplateMemberRepository(dataSource);
    } 
}

 

[ JPA ]

기존 반복 코드 감소

기본적 SGL 제공

패러다임 전환 (SGL과 데이터 중심의 설계 → 객체 중심의 설계)

 

JPA ( Java Persistence API ) : OMR 기술 , 데이터 단위로 객체 구현하고 데이터간의 관계 형성 

 

- build.gradle에 다음 내용 추가

//implementation 'org.springframework.boot:spring-boot-starter-jdbc'
	implementation 'org.springframework.boot:spring-boot-starter-data-jpa'

 

- application.properties 에 다음 내용 추가

spring.jpa.show-sql=true  
spring.jpa.hibernate.ddl-auto=none

 

JPA 엔티티 매핑

package hello.hellospring.domain;

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

@Entity  //JPA가 관리하는 엔티티가 된다.
public class Member {

    @Id      //primary key
    @GeneratedValue(strategy = GenerationType.IDENTITY) // DB에 값을 입력하면, 자동으로 id값 설정.(identity 전략)
    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;
    }
}

 

 

JPA 회원 리포지토리 생성

package hello.hellospring.repository;

import hello.hellospring.domain.Member;

import javax.persistence.EntityManager;
import java.util.List;
import java.util.Optional;

public class JpaMemberReporitory implements MemberRepository {

    private final EntityManager em; 
    public JpaMemberReporitory(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();
    }
}

 

서비스 계층에 트랜잭션 추가

import org.springframework.transaction.annotation.Transactional

@Transactional
public class MemberService {}

 

JPA를 통한 모든 데이터 변경은 트랜잭션 안에서 실행해야 한다.

 

 

[ 스프링 데이터 JPA ]

스프링 데이터 JPA 회원 리포지토리

package hello.hellospring.repository;

import hello.hellospring.domain.Member;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.Optional;

public interface SpringDataJpaMemberRepository extends JpaRepository<Member, Long>, MemberRepository {

    @Override
    Optional<Member> findByName(String name);
}

 

SpringDataJpaMemberRepository 인터페이스가 JpaRepository를 가지면, 구현체 자동 생성  → 스프링 빈으로 자동 등록

 

스프링 데이터 JPA 회원 리포지토리를 사용하도록 스프링 설정 변경

 

package hello.hellospring;

import hello.hellospring.repository.*;
import hello.hellospring.service.MemberService;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class SpringConfig {

   private final MemberRepository memberRepository;
   
   public SpringConfig(MemberRepository memberRepository) {
     this.memberRepository = memberRepository;
   }
 
   @Bean
   public MemberService memberService() {
     return new MemberService(memberRepository);
   }
   
}

 

스프링 데이터 JPA 제공 클래스