[Spring] 실습 2일차_Injection_Constructor & Setter 혼합

실습 2일차_Injection_Constructor & Setter 혼합

 

 Spring Injection_Constructor & Setter 혼합

MainClass.java

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);
		System.out.println(service);
		
		UserService service2 =
				ctx.getBean("service2", UserService.class);
		System.out.println(service2);
		
	}
}

UserService.java

package com.service;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

// POJO Class
public class UserService {
	// 인스턴스
	String mesg; // null ==> 외부에서 문자열을 주입
	int num; 	 // 0 ==> 외부에서 값을 주입
	
	// 생성자 주입
	public UserService(String m) {
		this.mesg = m;
	}
	
	// setter 메서드 주입
	public void setNum(int num) {
		this.num = num;
	}

	public UserService(int n) {
		this.num = n;
	}
	
	// overriding?
	public UserService(String m, int n) {
		this.mesg = m;
		this.num = n;
	}
	
	// getter
	public String getMesg() {
		return mesg;
	}
	
	public int getNum() {
		return num;
	}

	// toString
	@Override
	public String toString() {
		return "UserService [mesg=" + mesg + ", num=" + num + "]";
	}
	
}

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:c="http://www.springframework.org/schema/c"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

	<bean id="service" class="com.service.UserService">
		<constructor-arg name="m" value="고길동" />
		<property name="num" value="20"/> 
		<!-- 고길동이 생성자에 의해서 mesg 변수에 저장이 됨 -->
	</bean>

	<!-- 
		c namespace
		p namespace
	 -->
	 
	 <bean id="service2" class="com.service.UserService" c:m="고길동" p:num="30" />
	
</beans>

* 출력 화면 

 

 Spring Injection_shortcut_p 2

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);
		
		UserService service2 = ctx.getBean("service2", UserService.class);
		List<String> list2 = service2.list();
		System.out.println(list2);
		
	}
}

UserService.java

package com.service;
import java.util.List;
import com.dao.UserDAO;

// POJO Class
public class UserService {
	// property (인스턴스 변수)
	UserDAO dao;
	
	// setter 메서드 주입
	public UserService(UserDAO dao) {
		this.dao = dao;
	}
	
	public List<String> list(){
		return dao.list();
	}

}

UserDAO.java

package com.dao;
import java.util.Arrays;
import java.util.List;

public class UserDAO {

	// DB 연동 가정
	public List<String> list(){
		List<String> list = Arrays.asList("고길동", "신길동", "홍길동");
		return 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:c="http://www.springframework.org/schema/c"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

	<bean id="dao" class="com.dao.UserDAO" /> 		<!-- bean 태그로 등록하면 기본 생성자 호출 가능 -->
	<!--  다음 코드와 동일
		UserDAO userDAO = new UserDAO();
	 --> 
	<bean id="service" class="com.service.UserService"> <!-- id는 식별 가능한 값, class는 클래스 입력 -->
		<constructor-arg name="dao" ref="dao" />
	</bean>
	<!-- 다음 코드와 동일
		UserService service = new UserService();
		service.setDAO(UserDAO);
	 -->
	
	<!-- 
		c namespace
	 -->
	 
	 <bean id="service2" class="com.service.UserService" c:dao-ref="dao" />
	<!--  
		UserService service2= new UserService(dao);
	 --> 
</beans>

* 출력 화면 :

 

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