9장 DI 자동주입

package kr.co.softcampus.beans;

public class DataBean1 {
	
}

DataBean1클래스

 

package kr.co.softcampus.beans;

public class TestBean1 {
	private DataBean1 data1;
	private DataBean1 data2;
	public DataBean1 getData1() {
		return data1;
	}
	public void setData1(DataBean1 data1) {
		this.data1 = data1;
	}
	public DataBean1 getData2() {
		return data2;
	}
	public void setData2(DataBean1 data2) {
		this.data2 = data2;
	}
}

TestBean1클래스

 

<?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">
				<!-- 직접주입방법 -->		
	<bean id='obj1' class='kr.co.softcampus.beans.TestBean1'>
		<property name='data1' ref='data_bean1'/>
		<property name='data2' ref='data_bean1'/>
	</bean>
	
	<bean id='data_bean1' class='kr.co.softcampus.beans.DataBean1' scope='prototype'/><!-- 주입될때마다 새로운객체생성 -->

위 xml은 직접 주입해주는 방법이다

1. TestBean1객체를 생성하여 obj1라는 id만든다

2. 주입할때 마다 새로운 객체를 만드는 scope='prototype을 사용하여 DataBean1객체를 생성한다

3.setter 주입을 사용하여 2번에서 만든 DataBean1객체를 data1에 data2에 각각 주입시킨다.

 

<!-- 자동주입방법 -->
	
	
	<bean id='obj2' class='kr.co.softcampus.beans.TestBean1' autowire="byName"/>
	<bean id='data1' class='kr.co.softcampus.beans.DataBean1'/>
	<bean id='data2' class='kr.co.softcampus.beans.DataBean1'/>

 

위 xml은 자동으로 주입해주는 방법이다

autowire="byname"을 사용하면 빈 객체의 프로터피와 정의된 빈의 이름이 같은 것을 찾아 자동으로 주입해준다

자동주입은 클래스 객체타입만 가능하다 정수형이나 문자열타입은 직접주입해줘야함

 

package kr.co.softcampus.main;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import kr.co.softcampus.beans.TestBean1;
import kr.co.softcampus.beans.TestBean2;

public class MainClass {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("kr/co/softcampus/config/beans.xml");
		
		TestBean1 obj1 = ctx.getBean("obj1",TestBean1.class);
		System.out.println(obj1.getData1());
		System.out.println(obj1.getData2());
		
		System.out.println("------------------------");
		TestBean1 obj2 = ctx.getBean("obj2",TestBean1.class);
		System.out.println(obj2.getData1());
		System.out.println(obj2.getData2());
		
		ctx.close();//ioc컨테이너 해제 객체들 소멸됨
	}

}

 

직접 주입과 자동 주입을 main클래스에 객체화한 후 결과를 보겠다.

 

결과창

kr.co.softcampus.beans.DataBean1@15b204a1
kr.co.softcampus.beans.DataBean1@77167fb7
------------------------
kr.co.softcampus.beans.DataBean1@1fe20588
kr.co.softcampus.beans.DataBean1@6ce139a4

 

직접주입과 자동주입 두 방법다 객체가 잘 주입된것을 볼 수 있다.

 

 

타입을 통한 주입

 

TestBean2 클래스

package kr.co.softcampus.beans;

public class TestBean2 {
	private DataBean2 data1;
	private DataBean2 data2;
	
	public DataBean2 getData1() {
		return data1;
	}
	public void setData1(DataBean2 data1) {
		this.data1 = data1;
	}
	public DataBean2 getData2() {
		return data2;
	}
	public void setData2(DataBean2 data2) {
		this.data2 = data2;
	}
	
	
	
}

 

 

xml

    <bean id='obj3' class="kr.co.softcampus.beans.TestBean2" autowire="byType"/>
	<bean class='kr.co.softcampus.beans.DataBean2'/> 

TestBean2객체에서 프로퍼티 타입이 DataBean2가 있다면 자동으로 주입시켜줍니다

(이때 DataBean2객체가 한개이상 선언되어있다면 오류가 발생합니다)

 

main 클래스

package kr.co.softcampus.main;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import kr.co.softcampus.beans.TestBean1;
import kr.co.softcampus.beans.TestBean2;

public class MainClass {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("kr/co/softcampus/config/beans.xml");

		TestBean2 obj3 = ctx.getBean("obj3", TestBean2.class);
		System.out.println(obj3.getData1());
		System.out.println(obj3.getData2());

		ctx.close();// ioc컨테이너 해제 객체들 소멸됨
	}

}

 

출력창

kr.co.softcampus.beans.DataBean2@4f933fd1
kr.co.softcampus.beans.DataBean2@4f933fd1

 

생성자를 통한 주입

 

 

TestBean3

package kr.co.softcampus.beans;

public class TestBean3 {
	private int data1;
	private String data2;
	private DataBean2 data3;
	private DataBean2 data4;
	
	public TestBean3(DataBean2 data3, DataBean2 data4) {
		this.data3 = data3;
		this.data4 = data4;
	}
	
	public TestBean3(int data1, String data2, DataBean2 data3, DataBean2 data4) {
		this.data1 = data1;
		this.data2 = data2;
		this.data3 = data3;
		this.data4 = data4;
	}
	
	public int getData1() {
		return data1;
	}
	public void setData1(int data1) {
		this.data1 = data1;
	}
	public String getData2() {
		return data2;
	}
	public void setData2(String data2) {
		this.data2 = data2;
	}
	public DataBean2 getData3() {
		return data3;
	}
	public void setData3(DataBean2 data3) {
		this.data3 = data3;
	}
	public DataBean2 getData4() {
		return data4;
	}
	public void setData4(DataBean2 data4) {
		this.data4 = data4;
	}
	
	
}

 

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='data_bean2' class='kr.co.softcampus.beans.DataBean2'/>
	<!-- <bean class='kr.co.softcampus.beans.DataBean2'/>-->
	
	<bean id='obj5' class='kr.co.softcampus.beans.TestBean3' autowire="constructor"/>
	

</beans>

생성자의 매개변수타입과 xml에서 생성된 객체의 타입이 같다면 자동으로 주입시켜줍니다.

 

 

main class

package kr.co.softcampus.main;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import kr.co.softcampus.beans.TestBean1;
import kr.co.softcampus.beans.TestBean2;
import kr.co.softcampus.beans.TestBean3;

public class MainClass {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("kr/co/softcampus/config/beans.xml");
		

		
		TestBean3 obj5 = ctx.getBean("obj5", TestBean3.class);
		System.out.printf("obj5.data1 : %d\n", obj5.getData1());
		System.out.printf("obj5.data2 : %s\n", obj5.getData2());
		System.out.printf("obj5.data3 : %s\n", obj5.getData3());
		System.out.printf("obj5.data4 : %s\n", obj5.getData4());
		
		
		ctx.close();
	}

}

 

출력창

obj5.data1 : 0
obj5.data2 : null
obj5.data3 : kr.co.softcampus.beans.DataBean2@28feb3fa
obj5.data4 : kr.co.softcampus.beans.DataBean2@28feb3fa

 

xml 파일 namespace에 기본 자동주입설정 -> bean객체를 생성할때 autowire가 선언되있지않은 객체는 모두 이 기본값이 적용됨

 

<?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"
	default-autowire="byName">

 

기본값적용 해제하는방법

<bean id='obj9' class='kr.co.softcampus.beans.TestBean1' autowire="no"/>