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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