Spring MVC 서비스 계층

Service 클래스

애플리케이션에서 서비스의 의미는 비즈니스 영역과 관련이 있다. API 계층을 처리하는 controller 클래스와 service 클래스를 메소드 호출을 통해 상호 작용을 하도록 연동한다.

MemberService

public class MemberService {
    public Member createMember(Member member) {
        Member createdMember = member;
        return createdMember;
    }

    public Member updateMember(Member member) {
        Member updatedMember = member;
        return updatedMember;
    }

    public Member findMember(long memberId) {
        Member member = 
                new Member(memberId, "hgd@gmail.com", "홍길동", "010-1234-5678");
        return member;
    }

    public List<Member> findMembers() {
        List<Member> members = List.of(
                new Member(1, "hgd@gmail.com", "홍길동", "010-1234-5678"),
                new Member(2, "lml@gmail.com", "이몽룡", "010-1111-2222")
        );
        return members;
    }

    public void deleteMember(long memberId) {
    }
}

MemberController

@RestController
@RequestMapping("/v2/members")
@Validated
public class MemberController {
    private final MemberService memberService;

    public MemberController() {
        this.memberService = new MemberService(); // (1)
    }

    @PostMapping
    public ResponseEntity postMember(@Valid @RequestBody MemberPostDto memberDto) {
        Member member = new Member();
        member.setEmail(memberDto.getEmail());
        member.setName(memberDto.getName());
        member.setPhone(memberDto.getPhone());

        Member response = memberService.createMember(member);

        return new ResponseEntity<>(response, HttpStatus.CREATED);
    }

    @PatchMapping("/{member-id}")
    public ResponseEntity patchMember(
            @PathVariable("member-id") @Positive long memberId,
            @Valid @RequestBody MemberPatchDto memberPatchDto) {
        memberPatchDto.setMemberId(memberId);
        Member member = new Member();
        member.setMemberId(memberPatchDto.getMemberId());
        member.setName(memberPatchDto.getName());
        member.setPhone(memberPatchDto.getPhone());

        Member response = memberService.updateMember(member);

        return new ResponseEntity<>(response, HttpStatus.OK);
    }

    @GetMapping("/{member-id}")
    public ResponseEntity getMember(
            @PathVariable("member-id") @Positive long memberId) {
        Member response = memberService.findMember(memberId);
        return new ResponseEntity<>(response, HttpStatus.OK);
    }

    @GetMapping
    public ResponseEntity getMembers() {
        List<Member> response = memberService.findMembers();
        return new ResponseEntity<>(response, HttpStatus.OK);
    }

    @DeleteMapping("/{member-id}")
    public ResponseEntity deleteMember(
            @PathVariable("member-id") @Positive long memberId) {
        memberService.deleteMember(memberId);
        return new ResponseEntity(HttpStatus.NO_CONTENT);
    }
}

위 코드처럼 MemberController 클래스에서 MemeberService 클래스의 객체를 생성하여 해당 메소드를 사용한다.

Mapper

DTO(Data Transfer Object)클래스를 Entity 클래스로 변환하는 작업은 컨트롤러와 분리되어야 한다. 사용되는 계층에 따라 관심사(Aspect)가 다르기 때문이다. 그렇기에 이 역할을 하는 Mapper 클래스가 필요하다. Mapper를 사용하는 것이 코드가 더욱 간결해지고 생산성이 좋아진다.

MemberController

@RestController
@RequestMapping("/v4/members")
@Validated
public class MemberController {
    private final MemberService memberService;
    private final MemberMapper mapper;

    public MemberController(MemberService memberService, MemberMapper mapper) {
        this.memberService = memberService;
        this.mapper = mapper;
    }

    @PostMapping
    public ResponseEntity postMember(@Valid @RequestBody MemberPostDto memberDto) {
        Member member = mapper.memberPostDtoToMember(memberDto);
        Member response = memberService.createMember(member);

        return new ResponseEntity<>(mapper.memberToMemberResponseDto(response), 
                HttpStatus.CREATED);
    }

    @PatchMapping("/{member-id}")
    public ResponseEntity patchMember(
            @PathVariable("member-id") @Positive long memberId,
            @Valid @RequestBody MemberPatchDto memberPatchDto) {
        memberPatchDto.setMemberId(memberId);
        Member response = memberService.updateMember(mapper.memberPatchDtoToMember(memberPatchDto));
        return new ResponseEntity<>(mapper.memberToMemberResponseDto(response), 
                HttpStatus.OK);
    }

    @GetMapping("/{member-id}")
    public ResponseEntity getMember(
            @PathVariable("member-id") @Positive long memberId) {
        Member response = memberService.findMember(memberId);

        return new ResponseEntity<>(mapper.memberToMemberResponseDto(response), 
                HttpStatus.OK);
    }

    @GetMapping
    public ResponseEntity getMembers() {
        List<Member> members = memberService.findMembers();
        List<MemberResponseDto> response =
                members.stream()
                        .map(member -> mapper.memberToMemberResponseDto(member))
                        .collect(Collectors.toList());

        return new ResponseEntity<>(response, HttpStatus.OK);
    }

    @DeleteMapping("/{member-id}")
    public ResponseEntity deleteMember(
            @PathVariable("member-id") @Positive long memberId) {
        System.out.println("# delete member");
        memberService.deleteMember(memberId);

        return new ResponseEntity(HttpStatus.NO_CONTENT);
    }
}

컨트롤러에 Mapper를 적용한 모습이다.

MapStruct

MemberMapper

package com.codestates.member.mapstruct.mapper;

import com.codestates.member.dto.MemberPatchDto;
import com.codestates.member.dto.MemberPostDto;
import com.codestates.member.dto.MemberResponseDto;
import com.codestates.member.entity.Member;
import org.mapstruct.Mapper;

@Mapper(componentModel = "spring")
public interface MemberMapper {
    Member memberPostDtoToMember(MemberPostDto memberPostDto);
    Member memberPatchDtoToMember(MemberPatchDto memberPatchDto);
    MemberResponseDto memberToMemberResponseDto(Member member);
}

@Mapper 애너테이션을 통새 해당 인터페이스가 MapStruct의 매퍼 인터페이스로 정의가 된다. componetModel="spring"을 지정하면 스프링 빈으로 등록된다. Gradle의 build task를 실행하면 인터페이스의 구현체가 자동으로 생성된다.