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Spring注入内部bean

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目录

例如

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正如你所知道的Java内部类是其他类的范围内定义的,同样,内部bean是被其他bean的范围内定义的bean。因此<property/>或<constructor-arg/>元素内<bean/>元件被称为内部bean和它如下所示。 

<?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>


1 例如

我们使用Eclipse IDE,然后按照下面的步骤来创建一个Spring应用程序:

步骤 描述
1 Create a project with a name SpringExample and create a package com.yiibai under the src folder in the created project.
2 Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
3 Create Java classes TextEditorSpellChecker and MainApp under the com.yiibaipackage.
4 Create Beans configuration file Beans.xml under the src folder.
5 The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.

这里是TextEditor.java文件的内容: 

package com.yiibai;

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();
   }
}


下面是另外一个相关的类文件SpellChecker.java内容: 

package com.yiibai;

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

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


以下是MainApp.java文件的内容: 

package com.yiibai;

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();
   }
}


以下是配置文件beans.xml文件里面有配置为基于setter 注入,但使用内部bean: 

<?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.yiibai.TextEditor">
      <property name="spellChecker">
         <bean id="spellChecker" class="com.yiibai.SpellChecker"/>
       </property>
   </bean>

</beans>


创建源代码和bean配置文件来完成,让我们运行应用程序。如果一切顺利,这将打印以下信息:

Inside SpellChecker constructor.
Inside setSpellChecker.
Inside checkSpelling.

Spring注入内部bean


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