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1. Basic Controller
controller 파일을 만들어준다.
/src/main/java/com.example.demo/controller/TeepoController
package com.example.demo.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
public class TeepoController {
@GetMapping("teepo-string")
@ResponseBody
public String teepoString(@RequestParam("name") String name) {
return "hello-template" + name;
}
}여기서 @ResponseBody 는 API 응답으로 Body 안에 원하는 데이터를 넣어주겠다는 뜻이다.
브라우저에서 접속해보면
return 값이 정상적으로 반환되는 것을 확인할 수 있다.
2. JSON return Controller
json 형식으로 반환할 땐 아래와 같이 할 수 있다.
@GetMapping("teepo-api")
@ResponseBody
public Teepo teepoApi(@RequestParam("name") String name) {
Teepo teepo = new Teepo();
teepo.setName(name);
return teepo;
}
static class Teepo {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
서버를 키고 확인해보면,
이와같이 json 형식으로 데이터를 받은 것을 확인할 수 있다.
3. Member 객체 생성
domain 폴더를 만들고 Member 에 대한 객체를 만들어보자.
com.example.demo/domain/Member
package com.example.demo.domain;
public class Member {
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;
}
}
멤버 리포지토리 인터페이스를 만든다.
com.example.demo/repository/MemberRepository
package com.example.demo.repository;
import com.example.demo.domain.Member;
import java.util.List;
import java.util.Optional;
public interface MemberRepository {
Member save(Member member);
Optional<Member> findById(Long id);
Optional<Member> findByName(String name);
List<Member> findAll();
}여기서 Optional 이란 null 값을 처리하기 위해 한 번 감싸서 선언함을 의미한다.
리포지토리 메모리 구현체를 파일을 만든다.
com.example.demo/repository/MemoryMemberRepository
package com.example.demo.repository;
import com.example.demo.domain.Member;
import java.util.*;
/**
* 동시성 문제가 고려되어 있지 않음, 실무에서는 ConcurrentHashMap, AtomicLong 사용 고려
*/
public class MemoryMemberRepository implements MemberRepository {
private static Map<Long, Member> store = new HashMap<>();
private static long sequence = 0L;
@Override
public Member save(Member member) {
member.setId(++sequence);
store.put(member.getId(), member);
return member;
}
@Override
public Optional<Member> findById(Long id) {
return Optional.ofNullable(store.get(id));
}
@Override
public List<Member> findAll() {
return new ArrayList<>(store.values());
}
@Override
public Optional<Member> findByName(String name) {
return store.values().stream()
.filter(member -> member.getName().equals(name))
.findAny();
}
public void clearStore() {
store.clear();
}
}
4. Member Test
/src/text/java/com.example.demo/repository/MemoryMemberRepositoryTest
package com.example.demo.repository;
import com.example.demo.domain.Member;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Test;
import java.util.List;
import static org.assertj.core.api.Assertions.*;
class MemoryMemberRepositoryTest {
MemoryMemberRepository repository = new MemoryMemberRepository();
@AfterEach
public void afterEach() {
repository.clearStore();
}
@Test
public void save() {
//given
Member member = new Member();
member.setName("spring");
//when
repository.save(member);
//then
Member result = repository.findById(member.getId()).get();
assertThat(result).isEqualTo(member);
}
@Test
public void findByName() {
//given
Member member1 = new Member();
member1.setName("spring1");
repository.save(member1);
Member member2 = new Member();
member2.setName("spring2");
repository.save(member2);
//when
Member result = repository.findByName("spring1").get();
//then
assertThat(result).isEqualTo(member1);
}
@Test
public void findAll() {
//given
Member member1 = new Member();
member1.setName("spring1");
repository.save(member1);
Member member2 = new Member();
member2.setName("spring2");
repository.save(member2);
//when
List<Member> result = repository.findAll();
//then
assertThat(result.size()).isEqualTo(2);
}
}여기서 get 메소드는 Optional 객체 에서 데이터를 빼오는 방법이다.
5. Member Service
/src/main/java/com.example.demo/service/MemberService
package com.example.demo.service;
import com.example.demo.domain.Member;
import com.example.demo.repository.MemberRepository;
import com.example.demo.repository.MemoryMemberRepository;
import java.util.List;
import java.util.Optional;
public class MemberService {
private final MemberRepository memberRepository = new
MemoryMemberRepository();
/**
* 회원가입
*/
public Long join(Member member) {
validateDuplicateMember(member); //중복 회원 검증 memberRepository.save(member);
memberRepository.save(member);
return member.getId();
}
private void validateDuplicateMember(Member member) {
memberRepository.findByName(member.getName())
.ifPresent(m -> {
throw new IllegalStateException("이미 존재하는 회원입니다.");
});
}
/**
*전체 회원 조회
*/
public List<Member> findMembers() {
return memberRepository.findAll();
}
public Optional<Member> findOne(Long memberId) {
return memberRepository.findById(memberId);
} }
6. Member Service Test
먼저 회원 서비스 코드를 DI 가능하게 변경한다.
/src/main/java/com.example.demo/service/MemberService
...
private final MemberRepository memberRepository;
public MemberService(MemberRepository memberRepository) {
this.memberRepository = memberRepository;
}
...
클래스 안에서 마우스를 클릭하고 command + shift + t 를 누르면 Test를 자동으로 생성해줄 수 있다.
/src/test/java/com/example.demo/service/MemberServiceTest
package com.example.demo.service;
import com.example.demo.domain.Member;
import com.example.demo.repository.MemoryMemberRepository;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import static org.assertj.core.api.Assertions.*;
import static org.junit.jupiter.api.Assertions.*;
class MemberServiceTest {
MemberService memberService;
MemoryMemberRepository memberRepository;
@BeforeEach
public void beforeEach() {
memberRepository = new MemoryMemberRepository();
memberService = new MemberService(memberRepository);
}
@AfterEach
public void afterEach() {
memberRepository.clearStore();
}
@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.");
}
}
7. 컴포넌트 스캔과 자동 의존관계 설정
Service 를 사용하는 Controller를 만들어 보자.
/src/main/java/com.example.demo/controller/MemberController
package com.example.demo.controller;
import com.example.demo.service.MemberService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
@Controller
public class MemberController {
private final MemberService memberService;
@Autowired
public MemberController(MemberService memberService) {
this.memberService = memberService;
}
}생성자에 @Autowired 가 있으면 스프링이 연관된 객체를 스프링 컨테이너에서 찾아서 넣어준다. 이렇게 객체 의존관계를 외부에서 넣어주는 것을 DI (Dependency Injection), 의존성 주입이라 한다.
@Controller 가 있으면 스프링 빈으로 자동 등록된다.
Service 와 Repository에도 annotation 을 달아주자.
...
@Service
public class MemberService {
...
@Autowired
public MemberService(MemberRepository memberRepository) {
this.memberRepository = memberRepository;
}
...
...
@Repository
public class MemoryMemberRepository implements MemberRepository {
...
8. 자바 코드로 직접 스프링 빈 등록하기
회원 서비스와 회원 리포지토리의 @Service, @Repository, @Autowired 애노테이션을 제거하고 진행한다.
/src/test/java/com.example.demo/SpringConfig
package com.example.demo;
import com.example.demo.repository.MemberRepository;
import com.example.demo.repository.MemoryMemberRepository;
import com.example.demo.service.MemberService;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class SpringConfig {
@Bean
public MemberService memberService() {
return new MemberService(memberRepository());
}
@Bean
public MemberRepository memberRepository() {
return new MemoryMemberRepository();
}
}이렇게 하면 스프링이 실행되면서 의존성을 주입해준다.
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