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BeanFactoryPostProcessor
注意 BeanPostProcessor 引言 Spring的后处理器是spring对外开发的重要扩展点#xff0c;允许我们介入到Bean的整个实例化流程来#xff0c;以达到动态注册BeanDefintion#xff0c;动态修改BeanDefintion#xff0c;以及动态修改Be…目录 引言
BeanFactoryPostProcessor
注意 BeanPostProcessor 引言 Spring的后处理器是spring对外开发的重要扩展点允许我们介入到Bean的整个实例化流程来以达到动态注册BeanDefintion动态修改BeanDefintion以及动态修改Bean的作用。 Spring主要有两种后处理器 BeanFactoryPostProcessorBean工厂后处理器BeanDefintionMap填充完毕Bean实例化之前执行 BeanPostProcessorBean后处理器一般在Bean实例化之后填充单例池singletonObjects之前执行
BeanFactoryPostProcessor BeanFactoryPostProcessor是一个接口规范实现该接口的类只要交由Spring容器管理的话那么Spring就会回调该接口的方法用于对BeanDefinition注册和修改的功能 完善Bean实例化图 package com.xfy.processor;import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.beans.factory.support.RootBeanDefinition;public class MyBeanFactorypostprocessor implements BeanFactoryPostProcessor {public void postProcessBeanFactory(ConfigurableListableBeanFactory BeanFactory) throws BeansException {System.out.println(pPBF);//修改某个BeanDifinition的全限定名将某个Bean的类型改变BeanDefinition userDao BeanFactory.getBeanDefinition(userDao);userDao.setBeanClassName(com.xfy.service.impl.UserServiceImpl);//动态的去注册一个BeanDefinitionBeanDefinition BeanDefinition new RootBeanDefinition();BeanDefinition.setBeanClassName(com.xfy.dao.Impl.PersonDaoImpl);DefaultListableBeanFactory DBeanFactory (DefaultListableBeanFactory) BeanFactory;DBeanFactory.registerBeanDefinition(personDao,BeanDefinition);}
} bean classcom.xfy.processor.MyBeanFactorypostprocessor/bean
注意
Spring提供了一个BeanFactoryPostProcessor的子接口DBeanFactoryRegisterPostProcessor专门用于注册BeanDefintion操作 如下代码
package com.xfy.processor;import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.beans.factory.support.RootBeanDefinition;public class MyBeanFactorypostRegistryprocessor implements BeanDefinitionRegistryPostProcessor {public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {RootBeanDefinition beanDefinition new RootBeanDefinition(com.xfy.dao.Impl.PersonDaoImpl);beanDefinitionRegistry.registerBeanDefinition(personDao,beanDefinition);}public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {}
} BeanPostProcessor Bean被实例化后到最终缓存到名为singletonObjects单例池之前中间会经过Bean的初始化过程例如属性填充初始化方法init的执行等其中有一个对外进行扩展的点BeanPostProcessor。我们称为Bean后处理器跟上面的Bean工厂后处理器相似他也是一个接口实现该接口并被容器管理的BeanPostProcessor会在流程节点上被Spring自动调用 完善Bean实例化流程图 代码实现对Bean的属性赋值如下
package com.xfy.processor;import com.xfy.anno.MyComponent;
import com.xfy.dao.Impl.UserDaoImpl;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
MyComponent(mbpp)
public class MyBeanPostProcessor implements BeanPostProcessor {Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {if (bean instanceof UserDaoImpl){UserDaoImpl userDao (UserDaoImpl) bean;userDao.setName(haohao);}System.out.println(beanName postProcessBeforeInitialization);return bean;}Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {System.out.println(beanName postProcessAfterInitialization);return BeanPostProcessor.super.postProcessAfterInitialization(bean, beanName);}
}
