SOLID 규칙 적용 (+순수 자바 버전 , spring)

회원 예제

 

 

기획

• 회원 저장 로직
  1. 회원 저장
  2. 회원 조회
• 저장 방법
  1. 메모리 저장
  2. DB 저장

 

구조도

SOLID 규칙 적용

• 멤버

import lombok.Getter;
import lombok.Setter;

@Getter
@Setter
public class Member {
    private Long id;
    private String name;
    private Grade grade;

    public Member(Long id, String name, Grade grade){
        this.id = id;
        this.name = name;
        this.grade = grade;
    }


}

 

• 멤버서비스 인터페이스

public interface MemberService {
    void join(Member member);

    Member findMember(Long memberId);
}

• 멤버 저장소 인터페이스

public interface MemberRepository {
    void save(Member member);

    Member findById(Long memberId);
}

 

• 멤버와 멤버 저장소 연결 객체

public class MemberServiceImpl implements MemberService{

    private final MemberRepository memberRepository;


    public MemberServiceImpl(MemberRepository memberRepository){
        this.memberRepository = memberRepository;
    }

    @Override
    public void join(Member member) {
        memberRepository.save(member);
    }
    
    @Override
    public Member findMember(Long memberId) {
        return memberRepository.findById(memberId);
    }
}

 

• 멤버 구현체 주입 객체 (Config)

public class AppConfig {

    // 생성자 주입
    public MemberService memberService(){
        //return new MemberServiceImpl(new MemoryMemberRepository());
        return new MemberServiceImpl(new DbMemberRepository());
    }
    
    
}

 

• 멤버 저장소 구현체

public class DbMemberRepository implements MemberRepository{

    @Override
    public void save(Member member) {
        //db 전용 save 구현
    }

    @Override
    public Member findById(Long memberId) {
        //db 전용 findByid 구현
        return null;
    }
}


public class MemoryMemberRepository implements MemberRepository{

    //memory에 저장
    private static Map<Long, Member> store = new HashMap<>();

    @Override
    public void save(Member member) {
        store.put(member.getId(), member);
    }

    @Override
    public Member findById(Long memberId) {
        return store.get(memberId);
    }
}

 

테스트

public static void main(String []args){
    AppConfig appConfig = new AppConfig();
    MemberService memberService = appConfig.memberService();
    
    Member member = new Member(1L, "memberA", Grade.VIP);
    memberService.join(member);
    
    Member findMember = memberService.findMember(1L);
    System.out.println("new member = "+ member.getName());
    System.out.println("find member = "+ findMember.getName());
}

 

순수 자버 버전 SOLID

• 역할과 구현부를 분리하였다
  • 역할 -> MemberServiceImpl (MemberRepository)
  • 구현 -> MemoryMemberRepository,  DBMemberRepository
• 역할에서 실행할 구현부의 부분
  • AppConfig를 이용해서 생성자 주입 (다형성)
  • 추후) 스프링에서 @Configuration을 이용해서 관리하게 됨

 

Spring (+ @Configuration)

 

@Configuration
public class AppConfig {

    // 생성자 주입
    @Bean
    public MemberService memberService(){
        //return new MemberServiceImpl(new MemoryMemberRepository());
        return new MemberServiceImpl(new DbMemberRepository());
    }
    
    
}

• bean 객체를 이용해서 스프링이 관리
• @Configuration을 지정함으로써, 스프링이 config 파일을 인식

 

Spring 테스트

public static void main(String []args){
    //AppConfig appConfig = new AppConfig();
    //MemberService memberService = appConfig.memberService();
    
    ApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig.class);
    applicationContext.getBean("memberService", MemberService.class); // 인터페이스에 의존 (Bean으로 관리)
    
    Member member = new Member(1L, "memberA", Grade.VIP);
    memberService.join(member);
    
    Member findMember = memberService.findMember(1L);
    System.out.println("new member = "+ member.getName());
    System.out.println("find member = "+ findMember.getName());
}