《Pro Spring》学习笔记之beanFactory的嵌套使用

Spring支持BeanFactory的嵌套使用，我们可以把一个大的配置文件拆分成多个配置文件，然后参考面向对象的继承机制，进行配置文件的“继承”，当嵌套bean工厂时，Spring允许其中的beans讲字工厂作为父工厂的参考bean,唯一缺点是这只能在配置文件中使用，调用子bean工厂的getBean来访问父工厂的一个bean是不可能的 

嵌套BeanFacotry

 

realpathParent=System.getProperty("user.dir")+File.separator+"src"+File.separator+"ch4_BeanFactoryIterator"+File.separator+"applicationContext-parent.xml";

realpathChild=System.getProperty("user.dir")+File.separator+"src"+File.separator+"ch4_BeanFactoryIterator"+File.separator+"applicationContext-child.xml"; 

XmlBeanFactory  parentFactory=new XmlBeanFactory(new FileSystemResource(realpathParent));
 XmlBeanFactory  factory=new XmlBeanFactory(new FileSystemResource(realpathChild),parentFactory);

 

applicationContext-parent.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-2.0.xsd">
<bean id="injectBean" class="java.lang.String">
 <constructor-arg>
   <value>Bean in Parent</value>
 </constructor-arg>
</bean>

<bean id="injectBeanParent" class="java.lang.String">
 <constructor-arg>
   <value>Bean in Parent</value>
 </constructor-arg>
</bean>
</beans>

 

applicationContext-child.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-2.0.xsd">

<!-- 应用父bean的injectBeanParent -->
<bean id="target1" class="ch4_BeanFactoryIterator.SimpleTarget">
  <property name="val">
    <ref bean="injectBeanParent"/>
  </property>
</bean>
<!-- 应用子bean重写的injectBean -->
<bean id="target2" class="ch4_BeanFactoryIterator.SimpleTarget">
  <property name="val">
    <ref bean="injectBean"/>
  </property>
</bean>
<!-- 强制引用父bean的injectBean -->
<bean id="target3" class="ch4_BeanFactoryIterator.SimpleTarget">
  <property name="val">
    <ref parent="injectBean"/>
  </property>
</bean>


<!-- 重写injectBean -->
<bean id="injectBean" class="java.lang.String">
 <constructor-arg>
   <value>Bean in Child</value>
 </constructor-arg>
</bean>


</beans>

SimpleTarget.java

 

package ch4_BeanFactoryIterator;

public class SimpleTarget ...{
  private String val;

public String getVal() ...{
    return val;
}

public void setVal(String val) ...{
    this.val = val;
}
}

 

完整测试代码：

 

package ch4_BeanFactoryIterator;

import java.io.File;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;



public class TestSpring ...{
  public static void main(String args[])  throws Exception...{
      //获取bean factory
      BeanFactory factory=(BeanFactory)getBeanFactory();  //使用子beanFactory
      SimpleTarget target1=(SimpleTarget)factory.getBean("target1");
      SimpleTarget target2=(SimpleTarget)factory.getBean("target2");
      SimpleTarget target3=(SimpleTarget)factory.getBean("target3");
      System.out.println(target1.getVal());
      System.out.println(target2.getVal());
      System.out.println(target3.getVal());
      
      
  }
  public static BeanDefinitionRegistry getBeanFactory() ...{
      //获取bean factory
      String realpathParent="";
      String realpathChild="";
         //加载配置项
      realpathParent=System.getProperty("user.dir")+File.separator+"src"+File.separator+"ch4_BeanFactoryIterator"+File.separator+"applicationContext-parent.xml";
      realpathChild=System.getProperty("user.dir")+File.separator+"src"+File.separator+"ch4_BeanFactoryIterator"+File.separator+"applicationContext-child.xml"; 
      XmlBeanFactory  parentFactory=new XmlBeanFactory(new FileSystemResource(realpathParent));
      XmlBeanFactory  factory=new XmlBeanFactory(new FileSystemResource(realpathChild),parentFactory);
      
      return factory;
  }
}

 

运行结果

Bean in Parent
Bean in Child
Bean in Parent