인프런 커뮤니티 질문&답변

hello.core.lifecycle.NetworkClient.java

package hello.core.lifecycle;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;

public class NetworkClient implements InitializingBean, DisposableBean {

    private String url;

    public NetworkClient() {
        System.out.println("생성자 호출, url = " + url);
        /*connect();
        call("초기화 연결 메시지");*/
    }

    public void setUrl(String url) {
        this.url = url;
    }

    // 서비스 시작시 호출
    public void connect() {
        System.out.println("Connect: " + url);
    }

    public void call(String message) {
        System.out.println("call: " + url + ", message = " + message);
    }

    public void disconnect() {
        System.out.println("Close: " + url);
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        /* 생성자에 있던 코드를 이곳으로 ---> "생성과 초기화를 분리" */
        System.out.println("NetworkClient.afterPropertiesSet");
        connect();
        call("초기화 연결 메시지");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("NetworkClient.destroy");
        System.out.println("destroy() : url = " + url);
        disconnect();
    }
}

hello.core.lifecycle.BeanLifeCycleTest.java

package hello.core.lifecycle;

import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

public class BeanLifeCycleTest {

    @Test
    public void lifeCycleTest() {
        ConfigurableApplicationContext ac = new AnnotationConfigApplicationContext(NetworkClient.class);
        NetworkClient client = ac.getBean(NetworkClient.class);
        ac.close();
    }

    @Configuration
    static class LifeCycleConfig {

        @Bean
        public NetworkClient networkClient() {
            NetworkClient networkClient = new NetworkClient();
            networkClient.setUrl("http://hello-spring.net");
            return networkClient;
        }
    }
}

제 코드의 실행 결과

생성자 호출, url = null
NetworkClient.afterPropertiesSet
Connect: null
call: null, message = 초기화 연결 메시지
01:08:27.660 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@4a7f959b, started on Fri Dec 11 01:08:27 KST 2020
NetworkClient.destroy
destroy() : url = null
Close: null