실습 2일차_Setter Injection
의존성 주입의 방법으로는 크게 3가지가 있다.
- 생성자 주입(Constructor Injection)
- 필드 주입(Field Injection)
- 세터 주입(Setter Injection)
Spring Setter Injection 1
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.getMesg());
}
}UserService.java
package com.service;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
// POJO Class
public class UserService {
String mesg; // null ==> 외부에서 문자열을 주입
// setter 메서드 주입
public void setMesg(String mesg) {
System.out.println("setMesg 메서드");
this.mesg = mesg;
}
public String getMesg() {
return mesg;
}
}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"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="service" class="com.service.UserService"> <!-- id는 식별 가능한 값, class는 클래스 입력 -->
<property name="mesg" value="HelloWorld" /> <!-- System.out.println("setMesg 메서드"); property에 의해 출력 -->
</bean>
<!-- 다음 코드와 동일
UserService service = new UserService();
service.setMesg("HelloWorld");
-->
</beans>* 출력 화면
Spring Setter Injection 2
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.getMesg());
System.out.println(service);
UserService service2 =
ctx.getBean("service2", UserService.class);
System.out.println(service2.getMesg());
System.out.println(service2);
UserService service3 =
ctx.getBean("service3", UserService.class);
System.out.println(service3.getMesg());
System.out.println(service3);
}
}UserService.java
package com.service;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
// POJO Class
public class UserService {
// property (인스턴스 변수)
String mesg; // null ==> 외부에서 문자열을 주입
int num; // 0 ==> 외부에서 값을 주입
// setter 메서드 주입
public void setMesg(String mesg) {
this.mesg = mesg;
}
public void setNum(int num) {
this.num = num;
}
public void setMesgNum(String mesg, int num) {
this.mesg = mesg;
this.num = num;
}
// 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"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="service" class="com.service.UserService"> <!-- id는 식별 가능한 값, class는 클래스 입력 -->
<property name="mesg" value="HelloWorld" /> <!-- System.out.println("setMesg 메서드"); property에 의해 출력 -->
</bean>
<!-- 다음 코드와 동일
UserService service = new UserService();
service.setMesg("HelloWorld");
-->
<bean id="service2" class="com.service.UserService">
<property name="num" value="20" />
</bean>
<bean id="service3" class="com.service.UserService">
<property name="mesg" value="Happy" />
<property name="num" value="35" />
</bean>
<!-- setter based injection -->
</beans>* 출력 화면
Spring Setter Injection 3_Service_dao 추가
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.java
package com.service;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.dao.UserDAO;
// POJO Class
public class UserService {
// property (인스턴스 변수)
UserDAO dao;
// setter 메서드 주입
public void setDao(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", "홍길동", "신길동");
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"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="userDAO" class="com.dao.UserDAO" /> <!-- bean 태그로 등록하면 기본 생성자 호출 가능 -->
<!--
UserDAO userDAO = new UserDAO();
-->
<bean id="service" class="com.service.UserService"> <!-- id는 식별 가능한 값, class는 클래스 입력 -->
<property name="dao" ref="userDAO"></property>
</bean>
<!-- 다음 코드와 동일
UserService service = new UserService();
service.setDAO(UserDAO);
-->
</beans>* 출력 화면 :
출처
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