spring 后置处理器BeanFactoryPostProcessor和BeanPostProcessor的用法和区别

Posted 2020-06-13

 

主要区别就是： BeanFactoryPostProcessor可以修改BEAN的配置信息而BeanPostProcessor不能，下面举个例子说明

BEAN类：

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1. package com.springdemo.postProcessor;  
2.   
3. public class PostProcessorBean {  
4.     private String username;  
5.       
6.     private String password;  
7.   
8.     public String getPassword() {  
9.         return password;  
10.     }  
11.   
12.     public void setPassword(String password) {  
13.         this.password = password;  
14.     }  
15.   
16.     public String getUsername() {  
17.         return username;  
18.     }  
19.   
20.     public void setUsername(String username) {  
21.         this.username = username;  
22.     }  
23. }  

MyBeanPostProcessor类，实现了BeanPostProcessor接口:

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1. package com.springdemo.postProcessor;  
2.   
3. import org.springframework.beans.BeansException;  
4. import org.springframework.beans.factory.config.BeanPostProcessor;  
5.   
6. import com.springdemo.form.LoginForm;  
7.   
8. public class MyBeanPostProcessor implements BeanPostProcessor {  
9.   
10.       
11.       
12.     public Object postProcessAfterInitialization(Object bean, String beanName)  
13.             throws BeansException {  
14.         // TODO Auto-generated method stub  
15.         //如果是PostProcessorBean则username信息  
16.         if(bean instanceof PostProcessorBean)  
17.         {  
18.             System.out.println("PostProcessorBean Bean initialized");  
19.             PostProcessorBean pb = (PostProcessorBean)bean;  
20.               
21.             System.out.println("username:"+pb.getUsername());  
22.         }  
23.         return bean;  
24.     }  
25.   
26.     public Object postProcessBeforeInitialization(Object bean, String beanName)  
27.             throws BeansException {  
28.         // TODO Auto-generated method stub  
29.         if(bean instanceof PostProcessorBean)  
30.         {  
31.             System.out.println("PostProcessorBean Bean initializing");  
32.             PostProcessorBean pb = (PostProcessorBean)bean;  
33.               
34.             System.out.println("username:"+pb.getUsername());  
35.         }  
36.         return bean;  
37.     }  
38.   
39. }  

MyBeanFactoryPostProcessor实现了BeanFactoryPostProcessor接口:

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1. package com.springdemo.postProcessor;  
2.   
3. import org.springframework.beans.BeansException;  
4. import org.springframework.beans.MutablePropertyValues;  
5. import org.springframework.beans.factory.config.BeanDefinition;  
6. import org.springframework.beans.factory.config.BeanFactoryPostProcessor;  
7. import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;  
8.   
9. public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {  
10.   
11.     public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)  
12.             throws BeansException {  
13.         // TODO Auto-generated method stub  
14.         //BeanFactoryPostProcessor可以修改BEAN的配置信息而BeanPostProcessor不能  
15.         //我们在这里修改postProcessorBean的username注入属性  
16.         BeanDefinition bd = beanFactory.getBeanDefinition("postProcessorBean");  
17.         MutablePropertyValues pv =  bd.getPropertyValues();  
18.         if(pv.contains("username"))  
19.         {  
20.             pv.addPropertyValue("username", "xiaojun");  
21.         }  
22.           
23.     }  
24.   
25. }  

编写测试用例：

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1. package com.springdemo.test;  
2.   
3.   
4. import org.springframework.context.ApplicationContext;  
5. import org.springframework.context.support.ClassPathXmlApplicationContext;  
6.   
7. import com.springdemo.factory.ApplicationContextFactory;  
8.   
9. import com.springdemo.postProcessor.PostProcessorBean;  
10.   
11. import junit.framework.TestCase;  
12.   
13. public class BeanPostPorcessorTest extends TestCase {  
14.     private ApplicationContext context;  
15.     protected void setUp() throws Exception {  
16.         super.setUp();  
17.         String[] paths = {"classpath*:/spring/applicationContext-*.xml"};  
18.   
19.         context = new ClassPathXmlApplicationContext(paths);  
20.           
21.     }  
22.   
23.     protected void tearDown() throws Exception {  
24.         super.tearDown();  
25.     }  
26.       
27.     public void testBeanPostProcessor()  
28.     {  
29.           
30.     }  
31.     public void testBeanFactoryPostProcessor()  
32.     {  
33.         //PostProcessorBean bean =(PostProcessorBean)ServiceLocator.getService("postProcessorBean");  
34.         PostProcessorBean bean =(PostProcessorBean)context.getBean("postProcessorBean");  
35.         System.out.println("---------------testBeanFactoryPostProcessor----------------");  
36.         System.out.println("username:"+bean.getUsername());  
37.         System.out.println("password:"+bean.getPassword());  
38.         //  
39.     }  
40. }  

spring配置文件如下（先不启用MyBeanFactoryPostProcessor）：

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1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans xmlns="http://www.springframework.org/schema/beans"  
3.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
4.     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd">  
5.       
6.     <bean class="com.springdemo.postProcessor.MyBeanPostProcessor"></bean>  
7.     <!--我们先把BeanFactoryPostProcessor注释掉，不启用,然后查看测试输出结果    
8.     <bean class="com.springdemo.postProcessor.MyBeanFactoryPostProcessor"></bean>  
9.     -->  
10.     <bean id="postProcessorBean" class="com.springdemo.postProcessor.PostProcessorBean" >  
11.         <property name="username" value="test"></property>  
12.         <property name="password" value="test"></property>  
13.     </bean>  
14. </beans>  

测试输出结果如下：

PostProcessorBean Bean initializing
username:test
PostProcessorBean Bean initialized
username:test
---------------testBeanFactoryPostProcessor----------------
username:test
password:test

然后我们取消注释启用MyBeanFactoryPostProcessor，测试结果如下：

PostProcessorBean Bean initializing
username:xiaojun
PostProcessorBean Bean initialized
username:xiaojun
---------------testBeanFactoryPostProcessor----------------
username:xiaojun
password:test

从结果可以看出：BeanFactoryPostProcessor的回调比BeanPostProcessor要早，因为 BeanPostProcess中输出的username已经变成了xiaojun,而不是test.还有就是 BeanFactoryPostProcessor确实有能力改变初始化BEAN的内容，您可以试试在MyBeanPostProcess中试一试set 一下username看看能不能改变BEAN实例的内容(答案应该是否定的).

原文：

spring 后置处理器BeanFactoryPostProcessor和BeanPostProcessor的用法和区别