設計と設計発注と割引ドメイン

オーダーと割引ドメインの設計

注文および割引ポリシー

割引ポリシーインタフェース

package hello.core.discount;
import hello.core.member.Member;
public interface DiscountPolicy {

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

固定割引政策実施体

package hello.core.discount;

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

public class FixDiscountPolicy 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;
        }
    }
}

受注エンティティ

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;
    }

    //비즈니스 로직
    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 +
                '}';
    }
}

オーダーサービスインタフェース

package hello.core.order;

public interface OrderService {

    Order createOrder(Long memberId, String itemName, int itemPrice);
}

オーダーサービス実施機関

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);

    }
}

受注および割引ポリシーの実行

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(1L, "memberA", Grade.VIP);

        memberService.join(member);
        Order order = orderService.createOrder(memberId, "itemA", 10000);
        System.out.println("order = " + order.toString());


    }
}

テストコード

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;

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, "memberA", 10000);

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