主要提供两类扩展点 BeanPostProcessor 和 BeanFactoryPostProcessor


BeanPostProcessor 操作bean实例
BeanFactoryPostProcessor 对bean的元数据定义进行扩展  BeanDefiniton


BeanFactoryPostProcessor

在容器加载bean定义之后，bean创建之前，修改bean的定义属性

可同时配置多个 ，并通过设置'order'属性或实现order接口来控制执行次序

public interface BeanFactoryPostProcessor {
    void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;
}

内置实现

org.springframework.beans.factory.config.PropertyPlaceholderConfigurer
org.springframework.beans.factory.config.PropertyOverrideConfigurer
org.springframework.beans.factory.config.CustomEditorConfigurer  用来注册自定义的属性编辑器

CustomAutowireConfigurer

public abstract class PropertyResourceConfigurer extends PropertiesLoaderSupport
		implements BeanFactoryPostProcessor, PriorityOrdered

PropertySourceOrderingPostProcessor

ServletComponentRegisteringPostProcessor

新增一个字段

public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor{

   @Override
   public void postProcessBeanFactory(ConfigurableListableBeanFactory arg0)
         throws BeansException {
      BeanDefinition obj = arg0.getBeanDefinition("user0");
      MutablePropertyValues pv = obj.getPropertyValues();
      pv.add("testField", "testFieldValue");
   }
}




BeanPostProcessor

public interface BeanPostProcessor{
      public Object postProcessAfterInitialization(Object arg0, String arg1)
            throws BeansException ;
      public Object postProcessBeforeInitialization(Object arg0, String arg1)
            throws BeansException ;
}
参数 和 返回值说明
容器创建的对象和beanName，返回值是经过定制的对象



内置BeanPostProcessor实现
譬如对 @PostConstruct 注解处理
aop动态代理处理

可以定义多个BeanPostProcessor，执行顺序通过实现Ordered接口来控制
public interface Ordered {
    // Higher values are interpreted as lower priority.
    int getOrder();
}


ApplicationContextAwareProcessor
ServletContextAwareProcessor
WebServerFactoryCustomizerBeanPostProcessor
BeanValidationPostProcessor