[Spring] 실습 4일차_Component_Scan

실습 4일차_Component_Scan

 

 

 

 Spring Component_Scan

MainClass.java

import java.util.List;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
import com.service.UserService;

public class MainClass {
	public static void main(String[] args) {
		
		// IoC Container
		ApplicationContext ctx = 
				new GenericXmlApplicationContext("classpath:com/config/user.xml");

		UserService service = ctx.getBean("service", UserService.class);
		List<String> list = service.list();
		System.out.println(list);
	}
}

UserDAO.java

package com.dao;
import java.util.Arrays;
import java.util.List;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;

// @Component // @Component는 전부 Class Level
@Repository("dao")
public class UserDAO {
	
	public UserDAO() {
		System.out.println("UserDAO 생성자");
	}

	// DB 연동 가정
	public List<String> list(){
		List<String> list = Arrays.asList("고길동", "홍길동", "신길동");
		return list;
	}
}

UserService.java

package com.service;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;
import com.dao.UserDAO;

// POJO Class
// @Component // @Component는 전부 Class Level
@Service("service")
public class UserService {
	
	@Autowired
	UserDAO dao; // property (인스턴스 변수)
	
	public UserService() {
		System.out.println("UserService 생성자");
	}
	
	public List<String> list(){
		return dao.list();
	}
}

user.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd">

	<!-- @ 어노테이션 활성화 -->
	<!-- <context:annotation-config /> --> <!-- empty tag -->
	
	<!-- 내부적으로 <context:annotation-config /> 기능 포함 -->

	<!-- 마킹된(Component) Bean들의 Pakage Name 지정 -->
	<context:component-scan base-package="com.service, com.dao" /> <!-- empty tag -->
	<!-- <context:component-scan base-package="com.*" /> -->
</beans>

<!-- @ 어노테이션 활성화 -->
<context:annotation-config />

* context 활성화 방법

[Namespaces 탭] → [context] Check → Configure Namespaces 알림창 OK 버튼 마우스로 클릭 

 

 

 

* 출력 화면 

 

 출처

 

* Component_Scan : 

+ 강의 교재