BeanPostProcessor

原始碼如下：

public interface BeanPostProcessor {
 
    /**
     * Apply this BeanPostProcessor to the given new bean instance <i>before</i> any bean
     * initialization callbacks (like InitializingBean's <code>afterPropertiesSet</code>
     * or a custom init-method). The bean will already be populated with property values.
     * The returned bean instance may be a wrapper around the original.
     * 
 
@param bean the new bean instance
     * @param beanName the name of the bean
     * @return the bean instance to use, either the original or a wrapped one
     * @throws org.springframework.beans.BeansException in case of errors
     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
     
 
*/
    Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;
 
    /**
     * Apply this BeanPostProcessor to the given new bean instance <i>after</i> any bean
     * initialization callbacks (like InitializingBean's <code>afterPropertiesSet</code>
     * or a custom init-method). The bean will already be populated with property values.
     * The returned bean instance may be a wrapper around the original.
     * <p>In case of a FactoryBean, this callback will be invoked for both the FactoryBean
     * instance and the objects created by the FactoryBean (as of Spring 2.0). The
     * post-processor can decide whether to apply to either the FactoryBean or created
     * objects or both through corresponding <code>bean instanceof FactoryBean</code> checks.
     * <p>This callback will also be invoked after a short-circuiting triggered by a
     * {
 
@link InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation} method,
     * in contrast to all other BeanPostProcessor callbacks.
     * @param bean the new bean instance
     * @param beanName the name of the bean
     * @return the bean instance to use, either the original or a wrapped one
     * @throws org.springframework.beans.BeansException in case of errors
     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
     * @see org.springframework.beans.factory.FactoryBean
     */
    Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;
 
}

BeanPostProcessor是在spring容器載入了bean的定義檔案並且例項化bean之後執行的，可以在執行bean的初始化方法前後，新增一些自己的處理邏輯。BeanPostProcessor的執行順序是在BeanFactoryPostProcessor之後。

BeanFactoryPostProcessor

原始碼如下：

public interface BeanFactoryPostProcessor {
 
    /**
     * Modify the application context's internal bean factory after its standard
     * initialization. All bean definitions will have been loaded, but no beans
     * will have been instantiated yet. This allows for overriding or adding
     * properties even to eager-initializing beans.
     * @param beanFactory the bean factory used by the application context
     * @throws org.springframework.beans.BeansException in case of errors
     */
    void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;
 
}

可以在spring的bean建立之前，修改bean的定義屬性。也就是說，Spring允許BeanFactoryPostProcessor在容器例項化任何其它bean之前讀取配置元資料，並可以根據需要進行修改，例如可以把bean的scope從singleton改為prototype，也可以把property的值給修改掉。BeanFactoryPostProcessor是在spring容器載入了bean的定義檔案之後，在bean例項化之前執行的。