Spring之【Bean后置处理器】

目录

BeanPostProcessor

BeanPostProcessor的子接口

InstantiationAwareBeanPostProcessor

MergedBeanDefinitionPostProcessor

SmartInstantiationAwareBeanPostProcessor

DestructionAwareBeanPostProcessor

AutowiredAnnotationBeanPostProcessor

CommonAnnotationBeanPostProcessor 

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BeanPostProcessor

• Spring提供的扩展点
• 提供了两个默认方法，将bean对象和beanName作为参数
• Spring会在合适的时机执行对应的方法逻辑

package org.springframework.beans.factory.config;import org.springframework.beans.BeansException;
import org.springframework.lang.Nullable;public interface BeanPostProcessor {// bean初始化前@Nullabledefault Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {return bean;}// bean初始化后@Nullabledefault Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {return bean;}}

BeanPostProcessor的子接口

InstantiationAwareBeanPostProcessor

package org.springframework.beans.factory.config;public interface InstantiationAwareBeanPostProcessor extends BeanPostProcessor {// bean实例化前@Nullabledefault Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {return null;}// bean实例化后default boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {return true;}@Nullabledefault PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName)throws BeansException {return null;}
}

MergedBeanDefinitionPostProcessor

package org.springframework.beans.factory.support;public interface MergedBeanDefinitionPostProcessor extends BeanPostProcessor {void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName);default void resetBeanDefinition(String beanName) {}}

SmartInstantiationAwareBeanPostProcessor

package org.springframework.beans.factory.config;public interface SmartInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessor {@Nullabledefault Class<?> predictBeanType(Class<?> beanClass, String beanName) throws BeansException {return null;}@Nullabledefault Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName)throws BeansException {return null;}default Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {return bean;}
}

DestructionAwareBeanPostProcessor

package org.springframework.beans.factory.config;public interface DestructionAwareBeanPostProcessor extends BeanPostProcessor {void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException;default boolean requiresDestruction(Object bean) {return true;}}

AutowiredAnnotationBeanPostProcessor

• 将该BeanPostProcessor对应的BeanDefinition存到容器中，也就是DefaultListableBeanFactory中的beanDefinitionMap集合中

•  AbstractApplicationContext中refresh方法的registerBeanPostProcessors步骤中实例化并初始化好AutowiredAnnotationBeanPostProcessor对象，放入AbstractBeanfactory中的beanPostProcessors集合中

•  解析@Autowired、@Value注解

CommonAnnotationBeanPostProcessor 

• 将该BeanPostProcessor对应的BeanDefinition存到容器中，也就是DefaultListableBeanFactory中的beanDefinitionMap集合中

•  AbstractApplicationContext中refresh方法的registerBeanPostProcessors步骤中实例化并初始化好AutowiredAnnotationBeanPostProcessor对象，放入AbstractBeanfactory中的beanPostProcessors集合中

• 解析@Resource、@PostContruct、@PreDestroy