🌱마음을 정하지 않은 사장과 Spring을 사용해서 유연하게 코드를 진행하는 개발자

1. 상황

할인 정책 마음을 안 정한 사장과 머리가 아픈 개발자

현 상황은 vip에게 고정 할인 or 회원 등급에 따라 할인 등을 고민중이다.

 

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2. 주문 도메인 협력,역할,책임

 

 클라이언트가 주문을 하면,
 서비스는 회원 조회를 하고 그에 따른 할인을 적용하고 할인 결과를 포함한 주문 결과를 클라이언트에게 돌려준다. 

주문 도메인 전체

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3. 고정 할인 코드 설계

member 패키지는 회원 정보 로직이 / discount 페키지에는 할인 로직이  / order 페키지에는 주문 로직이 담겨있다.

순서는 각 패키지마다 DTO/Repository /Service/Main순서로 코드를 보여주겠다.

🥑 member 패키지

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🔻 member 객체 (DTO)

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;
    }
}

🔻 member Grade(enum)[고객 등급]

package hello.core.member;

public enum Grade {
    BASIC,
    VIP
}

🔻 MemberRepository (interface)

package hello.core.member;

public interface MemberRepository {
    void save(Member member);

    Member findById(Long memberId);
}

🔻 MemoryMemberRepository (구현체)

package hello.core.member;

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);
    }
}

🔻 MemberService(인터페이스)

package hello.core.member;

public interface MemberService {
    void join(Member member);
    
    Member findMember(Long memberId);
}

🔻 MemberServiceImpl(구현체)

package hello.core.member;

public class MemberServiceImpl implements MemberService {
    MemberRepository memberRepository=new MemoryMemberRepository();

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

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

🔻 MemberApp(메인클레스)

package hello.core;

import hello.core.member.*;

public class MemberApp {
    public static void main(String[] args) {
        MemberService memberService=new MemberServiceImpl();
        Member member=new Member(1L,"easy", Grade.VIP);
        memberService.join(member);
        Member findMember = memberService.findMember(1L);
        
    }
}

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🔻 TestCode

package hello.core.Member;


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

public class MemberServiceTest {
    MemberService memberService=new MemberServiceImpl();
    
    @Test
    void join(){
        Member member = new Member(1L,"easy", Grade.VIP);
        
        memberService.join(member);
        Member findMember= memberService.findMember(1L);

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

🥑 Discount패키지

 

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🔻 DiscountPolicy (인터페이스)

package hello.core.discount;

import hello.core.member.Member;

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

🔻 FixDiscountPolicy(fix할인률 구현체)

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;
        }
    }
}

---

🥑 Order패키지

🔻 Order(DTO)

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 String getItemName() {
        return itemName;
    }

    public int getItemPrice() {
        return itemPrice;
    }

    public int getDiscountPrice() {
        return discountPrice;
    }

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

🔻 orderService(인터페이스)

package hello.core.order;

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

🔻 orderServiceImpl

package hello.core.order;

import hello.core.discount.DiscountPolicy;
import hello.core.discount.FixDiscountPolicy;
import hello.core.member.Member;
import hello.core.member.MemberRepository;
import hello.core.member.MemoryMemberRepository;

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);
    }
}

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🥑 Main

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package hello.core;

import hello.core.member.Grade;
import hello.core.member.Member;
import hello.core.member.MemberService;
import hello.core.member.MemberServiceImpl;
import hello.core.order.Order;
import hello.core.order.OrderService;
import hello.core.order.OrderServiceImpl;

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

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

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

    }
}

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🥑 Test

package hello.core.order;

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

import static org.junit.jupiter.api.Assertions.*;

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);

    }

}

사실상.. 비즈니스 로직은 테스트를 통해서 확인해보는 습관을 가지는게 좋다.. !!

 

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4. 서비스 정책 전환..

 

이렇게 코드를 완성해봤는데...만약... 할인 정책이 바뀌면 어떻게 될까..???

만약 특정한 금액이 아니라, % 만큼 할인을 하게 된다면....???

어떤 코드들을 더 추가해야할까..?

다음글에서 이어서 작성하겠다!