스프링 핵심 원리 이해1 - 주문과 할인 도메인 개발

hello.core 밑에 discount 패키지를 만들고 DiscountPolicy라는 interface를 만든다.

 

// DiscountPolicy interface

package hello.core.discount;

import hello.core.member.Member;

public interface DiscountPolicy {

    /**
     * @return 할인 대상 금액
     */
    int discount(Member member, int price);
}

 

이거에 대한 구현체도 만들어 준다.

// FixDiscountPolicy

package hello.core.discount;

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

public class FixDicountPolicy implements DiscountPolicy{

    private int discountFixAmount = 1000; // 1000원 할인

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

 

 

주문쪽도 만들어 보자.

// Order class

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 서비스의 인터페이스도 만들어 보자.

package hello.core.order;

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

 

 

// OrderService interface

package hello.core.order;

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

주문 생성 = CreateOrder

 

이제 구현을 해주자.

OrderServiceImpl는 두개가 필요(MemoryMemberRepository / FixDiscountPolicy)

// OrderServiceImpl class

package hello.core.order;

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

public class OrderServiceImpl implements OrderService{


	// MemoryMemberRepository, FixDicountPolicy(고정할인정책)을 구현체로 씀
    private final MemberRepository memberRepository = new MemoryMemberRepository();
    private final DiscountPolicy discountPolicy = new FixDicountPolicy();

    @Override
    public Order createOrder(Long memberId, String itemName, int itemPrice) {
        Member member = memberRepository.findById(memberId);
        
        // 할인에 대한거는 discountPrice 니가 알아서 해라 => 단일 책임의 원칙 지킴
        // member을 통으로 넘김
        int discountPrice = discountPolicy.discount(member, itemPrice);

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

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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