[스프링 핵심](1) 회원, 주문과 할인 예제

먼저 Enum으로 회원 등급을 구현한다.

package hello.core.member;
 public enum Grade {
     BASIC,
     VIP
}

 

Member 도메인 객체를 구현한다.

package hello.core.member;

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;
    }

    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;
    }

    public Grade getGrade() {
        return grade;
    }

    public void setGrade(Grade grade) {
        this.grade = grade;
    }
}

 

MemberRepository도 구현한다. 추후에 리포지토리를 변경할 수 있으니(요구사항) 인터페이스로 구현이 필요하다.

package hello.core.member;

public interface MemberRepository {
    void save(Member member);
    Member findById(Long memberId);
}

 

인터페이스를 구현한 구현체를 만든다.

package hello.core.member;

import org.springframework.context.annotation.Primary;
import org.springframework.stereotype.Component;

import java.util.HashMap;
import java.util.Map;

public class MemoryMemberRepository implements MemberRepository {

    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);
    }
}

 

MemberService도 인터페이스를 만든다.

package hello.core.member;

public interface MemberService {

    void join(Member member);
    Member findMember(Long memberId);
}

 

MemberService를 구현한 MemberServiceImpl를 만든다.

package hello.core.member;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Primary;
import org.springframework.stereotype.Component;

public class MemberServiceImpl implements MemberService {

    private final MemberRepository memberRepository = new MemoryMemberRepository();

    @Override
    public void join(Member member) {
        memberRepository.save(member);
    }

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

 

잘 구현되었나 회원가입 테스트 코드를 작성한다.

package hello.core.member;

import hello.core.AppConfig;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class MemberServiceTest {

    MemberService memberService = new MemberServiceImpl();

    @Test
    void join() {
        //given
        Member member = new Member(1L, "memberA", Grade.VIP);

        //when
        memberService.join(member);
        Member findMember = memberService.findMember(1L);

        //then
        Assertions.assertThat(member).isEqualTo(findMember);
    }
}

 

할인 정책 인터페이스도 구현한다.

package hello.core.discount;

import hello.core.member.Member;

public interface DiscountPolicy {
    int discount(Member member, int price);
}

 

정액 할인 정책 구현체를 만든다.

package hello.core.discount;

import hello.core.member.Grade;
import hello.core.member.Member;

public class FixDiscountPolicy implements DiscountPolicy {

    private int discountFixAmount = 1000;

    @Override
    public int discount(Member member, int price) {
        if (member.getGrade() == Grade.VIP) {
            return discountFixAmount;
        } else {
            return 0;
        }
    }
}

 

 

주문 도메인 객체를 구현한다.

package hello.core.order;

public class Order {
    private Long memberId;
    private String itemName;
    private int itemPrice;
    private int discountPrice;

    public Order(Long memberId, String itemName, int itemPrice, int discountPrice) {
        this.memberId = memberId;
        this.itemName = itemName;
        this.itemPrice = itemPrice;
        this.discountPrice = discountPrice;
    }

    public int calculatePrice() {
        return itemPrice - discountPrice;
    }

    public Long getMemberId() {
        return memberId;
    }

    public void setMemberId(Long memberId) {
        this.memberId = memberId;
    }

    public String getItemName() {
        return itemName;
    }

    public void setItemName(String itemName) {
        this.itemName = itemName;
    }

    public int getItemPrice() {
        return itemPrice;
    }

    public void setItemPrice(int itemPrice) {
        this.itemPrice = itemPrice;
    }

    public int getDiscountPrice() {
        return discountPrice;
    }

    public void setDiscountPrice(int discountPrice) {
        this.discountPrice = discountPrice;
    }

    @Override
    public String toString() {
        return "Order{" +
                "memberId=" + memberId +
                ", itemName='" + itemName + '\'' +
                ", itemPrice=" + itemPrice +
                ", discountPrice=" + discountPrice +
                '}';
    }
}

 

 

주문 서비스 인터페이스를 구현한다.

package hello.core.order;

public interface OrderService {
    Order createOrder(Long memberId, String itemName, int itemPrice);
}

 

주문 서비스 인터페이스를 구현한 클래스를 만든다.

package hello.core.order;

import hello.core.annotation.MainDiscountPolicy;
import hello.core.discount.DiscountPolicy;
import hello.core.member.Member;
import hello.core.member.MemberRepository;
import lombok.RequiredArgsConstructor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

public class OrderServiceImpl implements OrderService{

    private final MemberRepository memberRepository = new MemoryMemberRepository();
    private final DiscountPolicy discountPolicy = new FixDiscountPolicy();

    @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);
    }
}

 

마지막으로, 주문과 할인 정책 테스트 코드를 작성한다.

package hello.core.order;

import hello.core.AppConfig;
import hello.core.member.Grade;
import hello.core.member.Member;
import hello.core.member.MemberService;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class OrderServiceTest {
    MemberService memberService = new MemberServiceImpl();
    OrderService orderService = new OrderServiceImpl();

    @Test
    void createOrder() {
        Long memberId = 1L;
        Member member = new Member(memberId, "memberA", Grade.VIP);
        memberService.join(member);

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

        Assertions.assertThat(order.getDiscountPrice()).isEqualTo(1000);

    }
}

 

 

이렇게 구현한 코드에는 의존관계가 인터페이스 뿐만 아니라 구현까지 모두 의존하는 문제점이 있다.

다음 글에서는 이러한 문제점을 해결해보고자 한다.