Interface BeanPostProcessor

All Known Subinterfaces:
DestructionAwareBeanPostProcessor, InstantiationAwareBeanPostProcessor, MergedBeanDefinitionPostProcessor, SmartInstantiationAwareBeanPostProcessor
All Known Implementing Classes:
AutowiredAnnotationBeanPostProcessor, InitDestroyAnnotationBeanPostProcessor
public interface BeanPostProcessor
Factory hook that allows for custom modification of new bean instances — for example, checking for marker interfaces or wrapping beans with proxies.

Typically, post-processors that populate beans via marker interfaces or the like will implement postProcessBeforeInitialization(Object, String), while post-processors that wrap beans with proxies will normally implement postProcessAfterInitialization(Object, String).

Registration

An ApplicationContext can autodetect BeanPostProcessor beans in its bean definitions and apply those post-processors to any beans subsequently created. A plain BeanFactory allows for programmatic registration of post-processors, applying them to all beans created through the bean factory.

When registering a BeanPostProcessor via an @Bean method in a @Configuration class, use a static method with ideally no dependencies in order to avoid eager initialization that can make other beans ineligible for full post-processing. See the "BeanPostProcessor-returning @Bean methods" section in

invalid reference 
@Bean
's javadoc for details and an example.

Ordering

BeanPostProcessor beans that are autodetected in an ApplicationContext will be ordered according to PriorityOrdered and Ordered semantics. In contrast, BeanPostProcessor beans that are registered programmatically with a BeanFactory will be applied in the order of registration; any ordering semantics expressed through implementing the PriorityOrdered or Ordered interface will be ignored for programmatically registered post-processors. Furthermore, the @Order annotation is not taken into account for BeanPostProcessor beans.

Since:
10.10.2003
Author:
Juergen Hoeller, Sam Brannen
See Also:

  • Method Summary

    Modifier and Type
    Method
    Description
    default @Nullable Object
    postProcessAfterInitialization(Object bean, String beanName)
    Apply this BeanPostProcessor to the given new bean instance after any bean initialization callbacks (like InitializingBean's afterPropertiesSet or a custom init-method).
    default @Nullable Object
    postProcessBeforeInitialization(Object bean, String beanName)
    Apply this BeanPostProcessor to the given new bean instance before any bean initialization callbacks (like InitializingBean's afterPropertiesSet or a custom init-method).

  • Method Details

    • postProcessBeforeInitialization

      default @Nullable Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException
      Apply this BeanPostProcessor to the given new bean instance before any bean initialization callbacks (like InitializingBean's 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.

      The default implementation returns the given bean as-is.

      Parameters:
      bean - the new bean instance
      beanName - the name of the bean
      Returns:
      the bean instance to use, either the original or a wrapped one; if null, no subsequent BeanPostProcessors will be invoked
      Throws:
      BeansException - in case of errors
      See Also:

    • postProcessAfterInitialization

      default @Nullable Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException
      Apply this BeanPostProcessor to the given new bean instance after any bean initialization callbacks (like InitializingBean's 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.

      In case of a FactoryBean, this callback will be invoked for both the FactoryBean instance and the objects created by the FactoryBean. The post-processor can decide whether to apply to either the FactoryBean or created objects or both through corresponding bean instanceof FactoryBean checks.

      This callback will also be invoked after a short-circuiting triggered by a InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation(Class, String) method, in contrast to all other BeanPostProcessor callbacks.

      The default implementation returns the given bean as-is.

      Parameters:
      bean - the new bean instance
      beanName - the name of the bean
      Returns:
      the bean instance to use, either the original or a wrapped one; if null, no subsequent BeanPostProcessors will be invoked
      Throws:
      BeansException - in case of errors
      See Also: