今天给大家介绍一下AbstractApplicationContext中refresh方法里的 invokeBeanFactoryPostProcessors(beanFactory)。
肯定听说过BeanFactoryPostProcessors和BeanPostProcessors这2个接口，他们都是spring框架留给开发人员的扩展点，不同的是他们2个的执行时机不同:BeanFactoryPostProcessors是在BeanFactory工厂获得后，对BeanFactory里面bean定义信息等进行修改添加,比如spring的注解开发就是在这里实现的；BeanPostProcessors是在bean实例出来，进行初始化前后进行调用，来增强bean的，比如我们的spring aop就是在这个基础进行的。
我们使用的注解开发就是在这里实现的，@Configuration 、@PropertySource、@ComponentScan 、@Import、 @ImportResource、@Bean等注解就是依靠ConfigurationClassPostProcessor类实现BeanFactoryPostProcessors接口完成的。
BeanDefinitionRegistryPostProcessor和 BeanFactoryPostProcessor关系
BeanFactoryPostProcessor：BeanFactory的后置处理，在BeanFactory初始化和加载完成xml配置文件后，进行后置处理。
BeanDefinitionRegistryPostProcessor：继承了BeanFactoryPostProcessor接口，并且多提供了一个接口方法用于处理postProcessBeanDefinitionRegistry。
总结：一般我们容器会先处理实现BeanDefinitionRegistryPostProcessor接口的类的方法，最后处理实现BeanFactoryPostProcessor接口的类的方法。而且ConfigurationClassPostProcessor就是实现了BeanDefinitionRegistryPostProcessor。
贴一段执行BeanFactoryPostProcessors代码：
public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, ListbeanFactoryPostProcessors) { ApplicationContext PostProcessorRegistrationDelegate q=PostProcessorRegistrationDelegate+is%3Aclosed+label%3A%22status%3A+declined%22 Set processedBeans = new HashSet<>(); if (beanFactory instanceof BeanDefinitionRegistry) { BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; List regularPostProcessors = new ArrayList<>(); List registryProcessors = new ArrayList<>(); 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<>(); // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered. 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); invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup()); currentRegistryProcessors.clear(); // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered. 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, beanFactory.getApplicationStartup()); currentRegistryProcessors.clear(); // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear. 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, beanFactory.getApplicationStartup()); currentRegistryProcessors.clear(); } // Now, invoke the postProcessBeanFactory callback of all processors handled so far. invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); } else { invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory); } String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false); 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); } } sortPostProcessors(priorityOrderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory); List orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size()); for (String postProcessorName : orderedPostProcessorNames) { orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } sortPostProcessors(orderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory); // Finally, invoke all other BeanFactoryPostProcessors. List nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size()); for (String postProcessorName : nonOrderedPostProcessorNames) { nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory); beanFactory.clearMetadataCache(); }
大家可以看到以上代码许多代码逻辑是重复的，只是获取的接口不同而已，下面给大家整理一下上面这段代码的执行逻辑。
- 首先会对传入的参数beanFactory进行判断是不是BeanDefinitionRegistry，这里传入的beanFactory是DefaultListableBeanFactory，因为在obtainFreshBeanFactory()方法中new出来的，而DefaultListableBeanFactory又是继承于BeanDefinitionRegistry，所以这里会进来。
if (beanFactory instanceof BeanDefinitionRegistry) { ................. } - 接下来会对传入的参数beanFactoryPostProcessors(一般为空)进行分类，分为实现BeanFactoryPostProcessor和BeanDefinitionRegistryPostProcessor接口的2个集合分别处理。
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; List
regularPostProcessors = new ArrayList<>(); List registryProcessors = new ArrayList<>(); for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) { if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) { BeanDefinitionRegistryPostProcessor registryProcessor = (BeanDefinitionRegistryPostProcessor) postProcessor; registryProcessor.postProcessBeanDefinitionRegistry(registry); registryProcessors.add(registryProcessor); } else { regularPostProcessors.add(postProcessor); } } - 接下来在beanfactory工厂中寻找实现BeanDefinitionRegistryPostProcessor接口的类，按照实现PriorityOrdered、Ordered、noOrdered顺序获取，分别调用执行invokeBeanDefinitionRegistryPostProcessors方法进行处理,最后调用invokeBeanFactoryPostProcessors方法。
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); invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup()); currentRegistryProcessors.clear(); Ordered............. noOrdered........... invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);4.最后寻找实现BeanFactoryPostProcessor接口的类，按照上面的顺序去做处理，调用invokeBeanFactoryPostProcessors方法处理。
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); } } // First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered. sortPostProcessors(priorityOrderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory); .............. .............
