[011] Spring - Injecting Inner Beans

Spring - Injecting Inner Beans

(원문 위치 : http://www.tutorialspoint.com/spring/spring_injecting_inner_beans.htm )

다른 class의 범위안에서 정의되어지는 java inner class와 유사하게 inner bean은 다른 bean의 범위내에서 정의되어지는 bean이다. 따라서 <property/> 또는 <constructor-arg/> 요소 내부의 <bean/> 요소는 inner bean으로 불려지고 아래와 같이 보여진다.

<?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-3.0.xsd">

   <bean id="outerBean" class="...">
      <property name="target">
         <bean id="innerBean" class="..."/>
      </property>
   </bean>

</beans>

Example:

[003] HelloWorld Example을 참조하여 프로젝트를 생성한다.

TextEditor.java:

package com.tutorialspoint;

public class TextEditor {
   private SpellChecker spellChecker;

   // a setter method to inject the dependency.
   public void setSpellChecker(SpellChecker spellChecker) {
      System.out.println("Inside setSpellChecker." );
      this.spellChecker = spellChecker;
   }
   
   // a getter method to return spellChecker
   public SpellChecker getSpellChecker() {
      return spellChecker;
   }

   public void spellCheck() {
      spellChecker.checkSpelling();
   }
}

SpellChecker.java:

package com.tutorialspoint;

public class SpellChecker {
   public SpellChecker(){
      System.out.println("Inside SpellChecker constructor." );
   }

   public void checkSpelling(){
      System.out.println("Inside checkSpelling." );
   }
   
}

MainApp.java:

package com.tutorialspoint;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainApp {
   public static void main(String[] args) {
      ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");

      TextEditor te = (TextEditor) context.getBean("textEditor");

      te.spellCheck();
   }
}

Beans.xml : inner bean을 사용하는  setter기반 삽입 설정

<?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-3.0.xsd">

   <!-- Definition for textEditor bean using inner bean -->
   <bean id="textEditor" class="com.tutorialspoint.TextEditor">
      <property name="spellChecker">
         <bean id="spellChecker" class="com.tutorialspoint.SpellChecker"/>
       </property>
   </bean>

</beans>

실행결과는 아래아 같다. inner bean을 사용하여 textEditor의 setSpellChecker()함수의 인자로 spellChecker를 전달하였다. 

Inside SpellChecker constructor.
Inside setSpellChecker.
Inside checkSpelling.