BeanFactory和ApplicationContext容器的bean后置处理器方式的不同

•Bean 后置处理器允许在调用初始化方法前后对 Bean 进行额外的处理.

一：BeanFactory

若使用BeanFactory，则必须要显示的调用其addBeanPostProcessor()方法进行注册，参数为BeanPostProcessor实现类的实例

1.spring.xml

 <bean class="test7" id="ts7" init-method="init" destroy-method="destroy">
      
      </bean>
     
   <bean class="test5"></bean>

2.

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;


public class test5 implements BeanPostProcessor{
	
	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName)
			throws BeansException {
		System.out.println("bean  "+beanName+"已经消亡");
		return null;
	}

	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName)
			throws BeansException {
		System.out.println("bean  "+beanName+"已经初始化");
		return null;
	}


}

3.

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;


public class test1{
      public static void main(String args[]){
    	 
    	  test5 beanPostProcessor = new test5();
    	  Resource resource = new FileSystemResource("applicationContext.xml");
    	   
    	  ConfigurableBeanFactory factory = new XmlBeanFactory(resource);
    	  
    	  factory.addBeanPostProcessor(beanPostProcessor);
    	   
    	  factory.getBean("ts7");//运行完这句完成注册输出：bean  ts5已经初始化
//bean  ts5已经消亡
    	  
      }
    
}

3.输出

bean  ts7已经初始化
我是init方法
bean  ts7已经消亡

二：ApplicationContext

如果是使用ApplicationContext，那么容器会在配置文件在中自动寻找实现了BeanPostProcessor接口的Bean，然后自动注册，我们要做的只是配置一个BeanPostProcessor实现类的Bean就可以了。

1.spring.xml

//配置一个BeanPostProcessor实现类的Bean,不需要像上面那样调用其addBeanPostProcessor()方法进行注册

      <bean class="test7" id="ts7" init-method="init" destroy-method="destroy">
      
      </bean> 
     
      <bean class="test5" ></bean>

2.

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;


public class test1{
      public static void main(String args[]){
    	/*注册方法一  */
    	  ConfigurableApplicationContext cf=new ClassPathXmlApplicationContext("applicationContext.xml"); 
    	  cf.close();//destroy-method="destroy"这里的方法消亡，不关
//postProcessAfterInitialization的事

} }

3.

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;


public class test5 implements BeanPostProcessor{
	
	
	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName)
			throws BeansException {
		System.out.println("bean  "+beanName+"已经消亡");
		return bean;
	}

	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName)
			throws BeansException {
		System.out.println("bean  "+beanName+"已经初始化");
		return bean;//返回不能为空
	}

	


}

4.

public class test7 {

	public void init(){
		System.out.println("我是init方法");
	}
	
	public void destroy(){
		System.out.println("我是destroy方法");
	}
	
}

5.输出

bean  ts7已经初始化
我是init方法
bean  ts7已经消亡
我是destroy方法