/**
 * Factory hook that allows for custom modification of new bean instances,
 * e.g. checking for marker interfaces or wrapping them with proxies.
 * 大体意思是可以检查相应的标识接口完成一些自定义功能实现，如包装目标对象到代理对象。
 */public interface BeanPostProcessor {
    /**
     * Apply this BeanPostProcessor to the given new bean instance <i>before</i> any bean
     * initialization callbacks (like InitializingBean's {@code afterPropertiesSet}
     * 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>The default implementation returns the given {@code bean} as-is.
     * @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;
     * if {@code null}, no subsequent BeanPostProcessors will be invoked
     * @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}
   * 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} 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.
   * <p>The default implementation returns the given {@code bean} as-is.
   * @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;
   * if {@code null}, no subsequent BeanPostProcessors will be invoked
   * @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;
}