org.springframework.beans.factory.config

## 接口 InstantiationAwareBeanPostProcessor

- 所有超级接口:
    BeanPostProcessor
  所有已知子接口:
    SmartInstantiationAwareBeanPostProcessor
  所有已知实现类:
    AutowiredAnnotationBeanPostProcessor, InstantiationAwareBeanPostProcessorAdapter, RequiredAnnotationBeanPostProcessor

      public interface InstantiationAwareBeanPostProcessor
      extends BeanPostProcessor

  Subinterface of `BeanPostProcessor` that adds a before-instantiation callback, and a callback after instantiation but before explicit properties are set or autowiring occurs.

  Typically used to suppress default instantiation for specific target beans, for example to create proxies with special TargetSources (pooling targets, lazily initializing targets, etc), or to implement additional injection strategies such as field injection.

  NOTE: This interface is a special purpose interface, mainly for internal use within the framework. It is recommended to implement the plain `BeanPostProcessor` interface as far as possible, or to derive from `InstantiationAwareBeanPostProcessorAdapter` in order to be shielded from extensions to this interface.

  从以下版本开始:
    1.2
  作者:
    Juergen Hoeller, Rod Johnson
  另请参阅:
    `org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#setCustomTargetSourceCreators`, `org.springframework.aop.framework.autoproxy.target.LazyInitTargetSourceCreator`

- - ### 方法概要

    所有方法 实例方法 默认方法
    限定符和类型 | 方法和说明
    --- | ---
    `default boolean` | `postProcessAfterInstantiation(Object bean, String beanName)` Perform operations after the bean has been instantiated, via a constructor or factory method, but before Spring property population (from explicit properties or autowiring) occurs.
    `default Object` | `postProcessBeforeInstantiation(Class<?> beanClass, String beanName)` Apply this BeanPostProcessor before the target bean gets instantiated.
    `default PropertyValues` | `postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName)` Post-process the given property values before the factory applies them to the given bean.

    - ### 从接口继承的方法 org.springframework.beans.factory.config.BeanPostProcessor

      `postProcessAfterInitialization, postProcessBeforeInitialization`

- - ### 方法详细资料

    - #### postProcessBeforeInstantiation

          @Nullable
          default Object postProcessBeforeInstantiation(Class<?> beanClass,
                                                                   String beanName)
                                                            throws BeansException

      Apply this BeanPostProcessor before the target bean gets instantiated. The returned bean object may be a proxy to use instead of the target bean, effectively suppressing default instantiation of the target bean.

      If a non-null object is returned by this method, the bean creation process will be short-circuited. The only further processing applied is the `BeanPostProcessor.postProcessAfterInitialization(java.lang.Object, java.lang.String)` callback from the configured `BeanPostProcessors`.

      This callback will be applied to bean definitions with their bean class, as well as to factory-method definitions in which case the returned bean type will be passed in here.

      Post-processors may implement the extended `SmartInstantiationAwareBeanPostProcessor` interface in order to predict the type of the bean object that they are going to return here.

      The default implementation returns `null`.

      参数:
        `beanClass` - the class of the bean to be instantiated
        `beanName` - the name of the bean
      返回:
        the bean object to expose instead of a default instance of the target bean, or `null` to proceed with default instantiation
      抛出:
        `BeansException` - in case of errors
      另请参阅:
        `postProcessAfterInstantiation(java.lang.Object, java.lang.String)`, `AbstractBeanDefinition.getBeanClass()`, `AbstractBeanDefinition.getFactoryMethodName()`

    - #### postProcessAfterInstantiation

          default boolean postProcessAfterInstantiation(Object bean,
                                                        String beanName)
                                                 throws BeansException

      Perform operations after the bean has been instantiated, via a constructor or factory method, but before Spring property population (from explicit properties or autowiring) occurs.

      This is the ideal callback for performing custom field injection on the given bean instance, right before Spring's autowiring kicks in.

      The default implementation returns `true`.

      参数:
        `bean` - the bean instance created, with properties not having been set yet
        `beanName` - the name of the bean
      返回:
        `true` if properties should be set on the bean; `false` if property population should be skipped. Normal implementations should return `true`. Returning `false` will also prevent any subsequent InstantiationAwareBeanPostProcessor instances being invoked on this bean instance.
      抛出:
        `BeansException` - in case of errors
      另请参阅:
        `postProcessBeforeInstantiation(java.lang.Class<?>, java.lang.String)`

    - #### postProcessPropertyValues

          @Nullable
          default PropertyValues postProcessPropertyValues(PropertyValues pvs,
                                                                      PropertyDescriptor[] pds,
                                                                      Object bean,
                                                                      String beanName)
                                                               throws BeansException

      Post-process the given property values before the factory applies them to the given bean. Allows for checking whether all dependencies have been satisfied, for example based on a "Required" annotation on bean property setters.

      Also allows for replacing the property values to apply, typically through creating a new MutablePropertyValues instance based on the original PropertyValues, adding or removing specific values.

      The default implementation returns the given `pvs` as-is.

      参数:
        `pvs` - the property values that the factory is about to apply (never `null`)
        `pds` - the relevant property descriptors for the target bean (with ignored dependency types - which the factory handles specifically - already filtered out)
        `bean` - the bean instance created, but whose properties have not yet been set
        `beanName` - the name of the bean
      返回:
        the actual property values to apply to the given bean (can be the passed-in PropertyValues instance), or `null` to skip property population
      抛出:
        `BeansException` - in case of errors
      另请参阅:
        `MutablePropertyValues`