spring 后置处理器BeanFactoryPostProcessor和BeanPostProcessor的用法...

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http://blog.csdn.net/xiao_jun_0820/article/details/7242379

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：
[java] view plaincopyprint?

• package com.springdemo.postProcessor;
• public class PostProcessorBean {
•     private String username;
•     private String password;
•     public String getPassword() {
•         return password;
•     }
•     public void setPassword(String password) {
•         this.password = password;
•     }
•     public String getUsername() {
•         return username;
•     }
•     public void setUsername(String username) {
•         this.username = username;
•     }
• }
  

package com.springdemo.postProcessor;public class PostProcessorBean {        private String username;                private String password;        public String getPassword() {                return password;        }        public void setPassword(String password) {                this.password = password;        }        public String getUsername() {                return username;        }        public void setUsername(String username) {                this.username = username;        }}
MyBeanPostProcessor类，实现了BeanPostProcessor接口:
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• package com.springdemo.postProcessor;
• import org.springframework.beans.BeansException;
• import org.springframework.beans.factory.config.BeanPostProcessor;
• import com.springdemo.form.LoginForm;
• public class MyBeanPostProcessor implements BeanPostProcessor {
•     public Object postProcessAfterInitialization(Object bean, String beanName)
•             throws BeansException {
•         // TODO Auto-generated method stub
•         //如果是PostProcessorBean则username信息
•         if(bean instanceof PostProcessorBean)
•         {
•             System.out.println("PostProcessorBean Bean initialized");
•             PostProcessorBean pb = (PostProcessorBean)bean;
•             System.out.println("username:"+pb.getUsername());
•         }
•         return bean;
•     }
•     public Object postProcessBeforeInitialization(Object bean, String beanName)
•             throws BeansException {
•         // TODO Auto-generated method stub
•         if(bean instanceof PostProcessorBean)
•         {
•             System.out.println("PostProcessorBean Bean initializing");
•             PostProcessorBean pb = (PostProcessorBean)bean;
•             System.out.println("username:"+pb.getUsername());
•         }
•         return bean;
•     }
• }
  

package com.springdemo.postProcessor;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanPostProcessor;import com.springdemo.form.LoginForm;public class MyBeanPostProcessor implements BeanPostProcessor {                        public Object postProcessAfterInitialization(Object bean, String beanName)                        throws BeansException {                // TODO Auto-generated method stub                //如果是PostProcessorBean则username信息                if(bean instanceof PostProcessorBean)                {                        System.out.println("PostProcessorBean Bean initialized");                        PostProcessorBean pb = (PostProcessorBean)bean;                                                System.out.println("username:"+pb.getUsername());                }                return bean;        }        public Object postProcessBeforeInitialization(Object bean, String beanName)                        throws BeansException {                // TODO Auto-generated method stub                if(bean instanceof PostProcessorBean)                {                        System.out.println("PostProcessorBean Bean initializing");                        PostProcessorBean pb = (PostProcessorBean)bean;                                                System.out.println("username:"+pb.getUsername());                }                return bean;        }}
MyBeanFactoryPostProcessor实现了BeanFactoryPostProcessor接口:
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• package com.springdemo.postProcessor;
• import org.springframework.beans.BeansException;
• import org.springframework.beans.MutablePropertyValues;
• import org.springframework.beans.factory.config.BeanDefinition;
• import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
• import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
• public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {
•     public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
•             throws BeansException {
•         // TODO Auto-generated method stub
•         //BeanFactoryPostProcessor可以修改BEAN的配置信息而BeanPostProcessor不能
•         //我们在这里修改postProcessorBean的username注入属性
•         BeanDefinition bd = beanFactory.getBeanDefinition("postProcessorBean");
•         MutablePropertyValues pv =  bd.getPropertyValues();
•         if(pv.contains("username"))
•         {
•             pv.addPropertyValue("username", "xiaojun");
•         }
•     }
• }
  

package com.springdemo.postProcessor;import org.springframework.beans.BeansException;import org.springframework.beans.MutablePropertyValues;import org.springframework.beans.factory.config.BeanDefinition;import org.springframework.beans.factory.config.BeanFactoryPostProcessor;import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {        public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)                        throws BeansException {                // TODO Auto-generated method stub                //BeanFactoryPostProcessor可以修改BEAN的配置信息而BeanPostProcessor不能                //我们在这里修改postProcessorBean的username注入属性                BeanDefinition bd = beanFactory.getBeanDefinition("postProcessorBean");                MutablePropertyValues pv =  bd.getPropertyValues();                if(pv.contains("username"))                {                        pv.addPropertyValue("username", "xiaojun");                }                        }}
编写测试用例：
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• package com.springdemo.test;
• import org.springframework.context.ApplicationContext;
• import org.springframework.context.support.ClassPathXmlApplicationContext;
• import com.springdemo.factory.ApplicationContextFactory;
• import com.springdemo.postProcessor.PostProcessorBean;
• import junit.framework.TestCase;
• public class BeanPostPorcessorTest extends TestCase {
•     private ApplicationContext context;
•     protected void setUp() throws Exception {
•         super.setUp();
•         String[] paths = {"classpath*:/spring/applicationContext-*.xml"};
•         context = new ClassPathXmlApplicationContext(paths);
•     }
•     protected void tearDown() throws Exception {
•         super.tearDown();
•     }
•     public void testBeanPostProcessor()
•     {
•     }
•     public void testBeanFactoryPostProcessor()
•     {
•         //PostProcessorBean bean =(PostProcessorBean)ServiceLocator.getService("postProcessorBean");
•         PostProcessorBean bean =(PostProcessorBean)context.getBean("postProcessorBean");
•         System.out.println("---------------testBeanFactoryPostProcessor----------------");
•         System.out.println("username:"+bean.getUsername());
•         System.out.println("password:"+bean.getPassword());
•         //
•     }
• }
  

package com.springdemo.test;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.springdemo.factory.ApplicationContextFactory;import com.springdemo.postProcessor.PostProcessorBean;import junit.framework.TestCase;public class BeanPostPorcessorTest extends TestCase {        private ApplicationContext context;        protected void setUp() throws Exception {                super.setUp();                String[] paths = {"classpath*:/spring/applicationContext-*.xml"};                context = new ClassPathXmlApplicationContext(paths);                        }        protected void tearDown() throws Exception {                super.tearDown();        }                public void testBeanPostProcessor()        {                        }        public void testBeanFactoryPostProcessor()        {                //PostProcessorBean bean =(PostProcessorBean)ServiceLocator.getService("postProcessorBean");                PostProcessorBean bean =(PostProcessorBean)context.getBean("postProcessorBean");                System.out.println("---------------testBeanFactoryPostProcessor----------------");                System.out.println("username:"+bean.getUsername());                System.out.println("password:"+bean.getPassword());                //        }}
spring配置文件如下（先不启用MyBeanFactoryPostProcessor）：
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• <?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 class="com.springdemo.postProcessor.MyBeanPostProcessor"></bean>
•     <!--我们先把BeanFactoryPostProcessor注释掉，不启用,然后查看测试输出结果
•     <bean class="com.springdemo.postProcessor.MyBeanFactoryPostProcessor"></bean>
•     -->
•     <bean id="postProcessorBean" class="com.springdemo.postProcessor.PostProcessorBean" >
•         <property name="username" value="test"></property>
•         <property name="password" value="test"></property>
•     </bean>
• </beans>
  

<?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 class="com.springdemo.postProcessor.MyBeanPostProcessor"></bean>        <!--我们先把BeanFactoryPostProcessor注释掉，不启用,然后查看测试输出结果          <bean class="com.springdemo.postProcessor.MyBeanFactoryPostProcessor"></bean>        -->        <bean id="postProcessorBean" class="com.springdemo.postProcessor.PostProcessorBean" >                <property name="username" value="test"></property>                <property name="password" value="test"></property>        </bean></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).
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