springboot-03

public static void invokeBeanFactoryPostProcessors(
            ConfigurableListableBeanFactory beanFactory, List beanFactoryPostProcessors) {
 
        // Invoke BeanDefinitionRegistryPostProcessors first, if any.
        Set processedBeans = new HashSet();
 
        if (beanFactory instanceof BeanDefinitionRegistry) {
            BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
            List regularPostProcessors = new LinkedList();
            List registryProcessors = new LinkedList();
 
            // 早期注册的BeanFactoryPostProcessor：
            // 1)org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer$ConfigurationWarningsPostProcessor
            // 2)org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer$\
            //   CachingMetadataReaderFactoryPostProcessor
            //      该processor将会注册一个新的BeanDefinition: CachingMetadataReaderFactory
            //      （此时BeanDefinitionRegistry共注册7个beanDefinition）
            // 3)org.springframework.boot.context.config.ConfigFileApplicationListener$PropertySourceOrderingPostProcessor
            for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
                if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
                    BeanDefinitionRegistryPostProcessor registryProcessor =
                            (BeanDefinitionRegistryPostProcessor) postProcessor;
                    registryProcessor.postProcessBeanDefinitionRegistry(registry);
                    registryProcessors.add(registryProcessor);
                }
                else {
                    regularPostProcessors.add(postProcessor);
                }
            }
 
            List currentRegistryProcessors = new ArrayList();
 
            // 从已经注册的beanDefinition中找出实现BeanDefinitionRegistryPostProcessor接口且实现PriorityOrdered的beanDefinition
            // 此时找出一个bean:  ConfigurationClassPostProcessor
            String[] postProcessorNames =
                    beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
            for (String ppName : postProcessorNames) {
                if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
                    currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
                    processedBeans.add(ppName);
                }
            }
            sortPostProcessors(currentRegistryProcessors, beanFactory);
            registryProcessors.addAll(currentRegistryProcessors);
            // BeanDefinitionRegistryPostProcessor.postProcessBeanDefinitionRegistry
            // 此时只有一个：ConfigurationClassPostProcessor
            invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
            currentRegistryProcessors.clear();
 
            // 从已经注册的beanDefinition中找出实现BeanDefinitionRegistryPostProcessor接口且实现Ordered的beanDefinition
            postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
            for (String ppName : postProcessorNames) {
                if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
                    currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
                    processedBeans.add(ppName);
                }
            }
            sortPostProcessors(currentRegistryProcessors, beanFactory);
            registryProcessors.addAll(currentRegistryProcessors);
            invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
            currentRegistryProcessors.clear();
 
            // 循环查找未处理的BeanDefinitionRegistryPostProcessor
            boolean reiterate = true;
            while (reiterate) {
                reiterate = false;
                postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
                for (String ppName : postProcessorNames) {
                    if (!processedBeans.contains(ppName)) {
                        currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
                        processedBeans.add(ppName);
                        reiterate = true;
                    }
                }
                sortPostProcessors(currentRegistryProcessors, beanFactory);
                registryProcessors.addAll(currentRegistryProcessors);
                invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
                currentRegistryProcessors.clear();
            }
 
            // 调用所有BeanDefinitionRegistryPostProcessor.postProcessBeanFactory方法
            invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
            // 调用早期注册的BeanFactoryPostProcessor.postProcessBeanFactory方法
            invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
        }
 
        else {
            // Invoke factory processors registered with the context instance.
            invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
        }
 
        // 从已经注册的beanDefinition中找出实现BeanFactoryPostProcessor接口的beanDefinition
        String[] postProcessorNames =
                beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
 
        // 将这些BeanFactoryPostProcessor根据不同优先级分配到不同集合
        List priorityOrderedPostProcessors = new ArrayList();
        List orderedPostProcessorNames = new ArrayList();
        List nonOrderedPostProcessorNames = new ArrayList();
        for (String ppName : postProcessorNames) {
            if (processedBeans.contains(ppName)) {
                // skip - already processed in first phase above
            }
            else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
                priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
            }
            else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
                orderedPostProcessorNames.add(ppName);
            }
            else {
                nonOrderedPostProcessorNames.add(ppName);
            }
        }
 
        // 先调用实现PriorityOrdered接口的BeanFactoryPostProcessors
        sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
        invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
 
        // 再调用实现Ordered接口的BeanFactoryPostProcessors
        List orderedPostProcessors = new ArrayList();
        for (String postProcessorName : orderedPostProcessorNames) {
            orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
        }
        sortPostProcessors(orderedPostProcessors, beanFactory);
        invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
 
        // 最后调用其他BeanFactoryPostProcessors
        List nonOrderedPostProcessors = new ArrayList();
        for (String postProcessorName : nonOrderedPostProcessorNames) {
            nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
        }
        invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
 
        // Clear cached merged bean definitions since the post-processors might have
        // modified the original metadata, e.g. replacing placeholders in values...
        beanFactory.clearMetadataCache();
    }