BeanFactoryPostProcessor 接口的 postProcessBeanFactory 方法的执行时机大体分为两类，第一类是 bean 继承了 BeanDefinitionRegistryPostProcessor 接口的，第二类是直接继承了 BeanFactoryPostProcessor 接口的

直接实现了 BeanDefinitionRegistryPostProcessor 接口

因为 BeanDefinitionRegistryPostProcessor 接口继承了 BeanFactoryPostProcessor 接口，所以它是 BeanFactoryPostProcessor 的子类

  1. public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor {
  2.     void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
  3. }

那么其 postProcessBeanFactory 方法的执行时机是在，完成了 postProcessBeanDefinitionRegistry 方法后，开始执行

直接实现了 BeanFactoryPostProcessor 接口

直接实现 BeanFactoryPostProcessor 接口的类，它的在执行时机晚于实现 BeanDefinitionRegistryPostProcessor 接口的类，不过它也有自己的一定执行策略

  1. 实现了 PriorityOrdered 接口
  2. 实现了 Ordered 接口
  3. 没有实现任何接口的
  1. List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
  2. List<String> orderedPostProcessorNames = new ArrayList<>();
  3. List<String> nonOrderedPostProcessorNames = new ArrayList<>();
  4. for (String ppName : postProcessorNames) {
  5.     if (processedBeans.contains(ppName)) {
  6.         // 已经在第一阶段执行过了，此处就不执行了
  7.         // skip - already processed in first phase above
  8.     }
  9.     else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
  10.         priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
  11.     }
  12.     else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
  13.         orderedPostProcessorNames.add(ppName);
  14.     }
  15.     else {
  16.         nonOrderedPostProcessorNames.add(ppName);
  17.     }
  18. }
  20. // First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
  21. sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
  22. invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
  24. // Next, invoke the BeanFactoryPostProcessors that implement Ordered.
  25. List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
  26. for (String postProcessorName : orderedPostProcessorNames) {
  27.     orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
  28. }
  29. sortPostProcessors(orderedPostProcessors, beanFactory);
  30. invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
  32. // Finally, invoke all other BeanFactoryPostProcessors.
  33. List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
  34. for (String postProcessorName : nonOrderedPostProcessorNames) {
  35.     nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
  36. }
  37. invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);