스프링 핵심 원리 - 조회한 빈이 모두 필요할 때, List , Map

의도적으로 정말 해당 타입의 스프링 빈이 다 필요한 경우도 있다.

예를 들어서 할인 서비스를 제공하는데, 클라이언트가 할인의 종류(rate, fix)를 선택할 수 있다고 가정해보자.

스프링을 사용하면 소위 말하는 전략 패턴을 매우 간단하게 구현할 수 있다

 

public class AllBeanTest {

    @Test
    void findAllBean(){
        ApplicationContext ac = new AnnotationConfigApplicationContext(DiscountService.class);
        //DiscountService가 스프링 컨테이너에 등록되면서
    }

    static class DiscountService{
        private final Map<String, DiscountPolicy> policyMap;
        private final List<DiscountPolicy> policies;
        
        @Autowired
        DiscountService(Map<String, DiscountPolicy> policyMap, List<DiscountPolicy> policies) {
            this.policyMap = policyMap;
            this.policies = policies;

            System.out.println("policyMap = " + policyMap);
            System.out.println("policies = " + policies);
        }
    }
}

아무것도 뜨지 않음. DiscountPolicy도 등록해줘야함

ApplicationContext ac = new AnnotationConfigApplicationContext(AutoAppConfig.class,DiscountService.class);

AutoAppConfig.class도 스프링빈에 등록해준다

package hello.core.autowired.allbean;

import hello.core.AutoAppConfig;
import hello.core.discount.DiscountPolicy;
import hello.core.member.Grade;
import hello.core.member.Member;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import java.util.List;
import java.util.Map;

import static org.assertj.core.api.Assertions.*;

public class AllBeanTest {

    @Test
    void findAllBean(){
        ApplicationContext ac = new AnnotationConfigApplicationContext(AutoAppConfig.class,DiscountService.class);
        //AutoAppConfig.class와 DiscountService가 스프링 컨테이너에 등록된다.
        DiscountService discountService = ac.getBean(DiscountService.class);
        Member member = new Member(1L, "userA", Grade.VIP);
        int discountPrice = discountService.discount(member,10000,"fixDiscountPolicy");


        assertThat(discountService).isInstanceOf(DiscountService.class);
        assertThat(discountPrice).isEqualTo(1000);

    }

    static class DiscountService{
        private final Map<String, DiscountPolicy> policyMap;
        private final List<DiscountPolicy> policies;

        @Autowired
        DiscountService(Map<String, DiscountPolicy> policyMap, List<DiscountPolicy> policies) {
            this.policyMap = policyMap;
            this.policies = policies;

            System.out.println("policyMap = " + policyMap);
            System.out.println("policies = " + policies);
        }

        public int discount(Member member, int price, String discountCode) {
            DiscountPolicy discountPolicy = policyMap.get(discountCode);
            return discountPolicy.discount(member,price);
        }
    }
}