스프링 빈 조회 - 기본

스프링 컨테이너에서 스프링 빈을 찾는 가장 기본적인 조회 방법

# ApplicationContext.getBean(빈이름, 타입)
# ApplicationContext.getBean(타입)
# ApplicationContext.getBean(빈이름)

-> 빈 이름, 타입으로 빈 객체(인스턴스) 조회

조회 대상 스프링 빈이 없으면 예외 발생

NoSuchBeanDefinitionException: No bean named 'xxxxx' available

예제)
- src/test/java/hello/core/beanfind/ApplicationContextBasicFindTest.java

package hello.core.beanfind;

import hello.core.AppConfig;
import hello.core.member.MemberService;
import hello.core.member.MemberServiceImpl;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

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

class ApplicationContextBasicFindTest {

    AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(AppConfig.class);

    @Test
    @DisplayName("빈 이름, 타입으로 조회")
    void findBeanByName() {
        MemberService memberService = ac.getBean("memberService", MemberService.class);
        assertThat(memberService).isInstanceOf(MemberServiceImpl.class);
    }

    @Test
    @DisplayName("이름 없이 타입만으로 조회")
    void findBeanByType() {
        MemberService memberService = ac.getBean(MemberService.class);
        assertThat(memberService).isInstanceOf(MemberServiceImpl.class);
    }

    @Test
    @DisplayName("구현체 타입으로 조회")
    void findBeanByName2() {
        MemberServiceImpl memberService = ac.getBean("memberService", MemberServiceImpl.class);
        assertThat(memberService).isInstanceOf(MemberServiceImpl.class);
    }

    @Test
    @DisplayName("빈 이름으로만 조회")
    void findBeanByName3() {
        MemberService memberService = (MemberService) ac.getBean("memberService");
        assertThat(memberService).isInstanceOf(MemberServiceImpl.class);
    }

    @Test
    @DisplayName("빈 이름으로 조회X")
    void findBeanByNameX() {
        // ac.getBean("xxxxx", MemberService.class);
        assertThrows(NoSuchBeanDefinitionException.class, () -> ac.getBean("xxxxx", MemberService.class));
    }

}

구현체 타입으로 조회하면, 변경시 유연성이 떨어진다. (구현에 의존하지 않고 역할에 의존하도록 하기)


참고링크 : https://www.inflearn.com/course/%EC%8A%A4%ED%94%84%EB%A7%81-%ED%95%B5%EC%8B%AC-%EC%9B%90%EB%A6%AC-%EA%B8%B0%EB%B3%B8%ED%8E%B8?cid=325969

스프링 핵심 원리 - 기본편| 김영한 - 인프런 강의