14강. 관심사의 분리

결국, 역할은 있지만 그걸 구체적으로 누가 할지 선택하는 감독자 역할이 필요.

그 감독자가 컨테이너

 

 

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);
    }
}

기존처럼 구현체를 직접생성하지 말고, 오직 추상체만 의존한 뒤, 생성자를 통해 외부에서 주입.

잘 보면 아름답게도 모든 코드들이 추상체에만 의존하고 있음.

 

public class OrderServiceImpl implements OrderService{
    private MemberRepository memberRepository;
    private DiscountPolicy discountPolicy;

    public OrderServiceImpl(MemberRepository memberRepository, DiscountPolicy discountPolicy) {
        this.memberRepository = memberRepository;
        this.discountPolicy = discountPolicy;
    }
    @Override
    public Order createOrder(Long memberId, String itemName, int itemPrice) {
        Member member = memberRepository.findById(memberId);
        int discountPrice = discountPolicy.discount(member, itemPrice);

        return new Order(memberId, itemName, itemPrice, discountPrice);
    }
}

이것도

 

 

 

public class AppConfig {
    public MemberService memberService(){
        return new MemberServiceImpl(new MemoryMemberRepository());
    }

    public OrderService orderService(){
        return new OrderServiceImpl(new MemoryMemberRepository(), new FixDscountPolicy());
    }
}

주입해주는 역할, 역할을 관리해주는 역할.

 

 

정확히 역할만 의존하고, 실행하는 역할은 위가 해줌.

관심사의 분리.

 

 

 

public class MemberApp {
    public static void main(String[] args) {
        AppConfig appConfig = new AppConfig();

        MemberService memberService = appConfig.memberService();
        //MemberService memberService = new MemberServiceImpl();

        Member member1 = new Member(1L, "kim", Grade.BASIC);
        memberService.join(member1);

        Member findMember = memberService.findMember(1L);
        System.out.println("findMember = " + findMember.getName());
        System.out.println("member1 = " + member1.getName());
    }
}

appConfig를 통해 의존관계 주입.

 

public class OrderApp {
    public static void main(String[] args) {
        AppConfig appConfig = new AppConfig();
        MemberService memberService = appConfig.memberService();
        OrderService orderService = appConfig.orderService();

        Long memberId = 1L;
        Member member = new Member(memberId, "memberA", Grade.VIP);
        memberService.join(member);

        Order order = orderService.createOrder(memberId,"itemA", 10000);

        System.out.println("order = " + order);
        System.out.println("order.calculatePrice() = " + order.calculatePrice());

    }
}