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{@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName)throws BeansException {System.out.println("bean  "+beanName+"已经消亡");return null;}@Overridepublic 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{@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName)throws BeansException {System.out.println("bean  "+beanName+"已经消亡");return bean;}@Overridepublic 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