Spring源码之invokeBeanFactoryPostProcessors
概述
invokeBeanFactoryPostProcessors办法中次要是解决BeanDefinitionRegistryPostProcessor和BeanFactoryPostProcessor，BeanDefinitionRegistryPostProcessor是BeanFactoryPostProcessor的子接口，具备更弱小的性能。这两个接口是Spring再初始化前一个重要的扩大点。
invokeBeanFactoryPostProcessors源码剖析
public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) { // Invoke BeanDefinitionRegistryPostProcessors first, if any. Set<String> processedBeans = new HashSet<String>(); // 判断beanFactory是否为BeanDefinitionRegistry，beanFactory为DefaultListableBeanFactory, // 而DefaultListableBeanFactory实现了BeanDefinitionRegistry接口，因而这边为true if (beanFactory instanceof BeanDefinitionRegistry) { BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; // 用于寄存一般的BeanFactoryPostProcessor List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>(); // 用于寄存BeanDefinitionRegistryPostProcessor List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>(); // 首先解决入参中的beanFactoryPostProcessors // 遍历所有的beanFactoryPostProcessors, 将BeanDefinitionRegistryPostProcessor和一般BeanFactoryPostProcessor辨别开 for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) { if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) { // 如果是BeanDefinitionRegistryPostProcessor BeanDefinitionRegistryPostProcessor registryProcessor = (BeanDefinitionRegistryPostProcessor) postProcessor; // 间接执行BeanDefinitionRegistryPostProcessor接口的postProcessBeanDefinitionRegistry办法 registryProcessor.postProcessBeanDefinitionRegistry(registry); //@3 // 增加到registryProcessors(用于最初执行postProcessBeanFactory办法) registryProcessors.add(registryProcessor); } else { // 否则，只是一般的BeanFactoryPostProcessor // 增加到regularPostProcessors(用于最初执行postProcessBeanFactory办法) regularPostProcessors.add(postProcessor); } } // Do not initialize FactoryBeans here: We need to leave all regular beans // uninitialized to let the bean factory post-processors apply to them! // Separate between BeanDefinitionRegistryPostProcessors that implement // PriorityOrdered, Ordered, and the rest. // 用于保留本次要执行的BeanDefinitionRegistryPostProcessor List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>(); // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered. // 调用所有实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor实现类 // 找出所有实现BeanDefinitionRegistryPostProcessor接口的Bean的beanName //@1 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); //遍历postProcessorNames for (String ppName : postProcessorNames) { // 校验是否实现了PriorityOrdered接口 if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { // 获取ppName对应的bean实例, 增加到currentRegistryProcessors中, // beanFactory.getBean: 这边getBean办法会触发创立ppName对应的bean对象, 目前暂不深刻解析 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); // 将要被执行的退出processedBeans，防止后续反复执行 processedBeans.add(ppName); } } //进行排序(依据是否实现PriorityOrdered、Ordered接口和order值来排序) sortPostProcessors(currentRegistryProcessors, beanFactory); // 增加到registryProcessors(用于最初执行postProcessBeanFactory办法) registryProcessors.addAll(currentRegistryProcessors); // 遍历currentRegistryProcessors, 执行postProcessBeanDefinitionRegistry办法 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); // 执行结束后, 清空currentRegistryProcessors currentRegistryProcessors.clear(); // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered. // 调用所有实现了Ordered接口的BeanDefinitionRegistryPostProcessor实现类（过程跟下面的步骤3根本一样） // 找出所有实现BeanDefinitionRegistryPostProcessor接口的类, 这边反复查找是因为执行完下面的BeanDefinitionRegistryPostProcessor, // 可能会新增了其余的BeanDefinitionRegistryPostProcessor, 因而须要从新查找 // @2 postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { // 校验是否实现了Ordered接口，并且还未执行过 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); // 遍历currentRegistryProcessors, 执行postProcessBeanDefinitionRegistry办法 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear. // 最初, 调用所有剩下的BeanDefinitionRegistryPostProcessors boolean reiterate = true; while (reiterate) { reiterate = false; // 找出所有实现BeanDefinitionRegistryPostProcessor接口的类 postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { // 跳过曾经执行过的 if (!processedBeans.contains(ppName)) { currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); // 如果有BeanDefinitionRegistryPostProcessor被执行, 则有可能会产生新的BeanDefinitionRegistryPostProcessor, // 因而这边将reiterate赋值为true, 代表须要再循环查找一次 reiterate = true; } } sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); // 遍历currentRegistryProcessors, 执行postProcessBeanDefinitionRegistry办法 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); } // Now, invoke the postProcessBeanFactory callback of all processors handled so far. //调用所有BeanDefinitionRegistryPostProcessor的postProcessBeanFactory办法(BeanDefinitionRegistryPostProcessor继承自BeanFactoryPostProcessor) invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); // 最初, 调用入参beanFactoryPostProcessors中的一般BeanFactoryPostProcessor的postProcessBeanFactory办法 invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); } else { // Invoke factory processors registered with the context instance. invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory); } // 到这里 , 入参beanFactoryPostProcessors和容器中的所有BeanDefinitionRegistryPostProcessor曾经全副处理完毕, // 上面开始解决容器中的所有BeanFactoryPostProcessor // Do not initialize FactoryBeans here: We need to leave all regular beans // uninitialized to let the bean factory post-processors apply to them! // 找出所有实现BeanFactoryPostProcessor接口的类 //@3 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false); // Separate between BeanFactoryPostProcessors that implement PriorityOrdered, // Ordered, and the rest. // 用于寄存实现了PriorityOrdered接口的BeanFactoryPostProcessor List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); // 用于寄存实现了Ordered接口的BeanFactoryPostProcessor的beanName List<String> orderedPostProcessorNames = new ArrayList<String>(); // 用于寄存一般BeanFactoryPostProcessor的beanName List<String> nonOrderedPostProcessorNames = new ArrayList<String>(); // 遍历postProcessorNames, 将BeanFactoryPostProcessor按实现PriorityOrdered、实现Ordered接口、一般三种辨别开 for (String ppName : postProcessorNames) { // 跳过曾经执行过的 if (processedBeans.contains(ppName)) { // skip - already processed in first phase above } else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { // 增加实现了PriorityOrdered接口的BeanFactoryPostProcessor priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class)); } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) { // 增加实现了Ordered接口的BeanFactoryPostProcessor的beanName orderedPostProcessorNames.add(ppName); } else { // 增加剩下的一般BeanFactoryPostProcessor的beanName nonOrderedPostProcessorNames.add(ppName); } } // First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered. // 调用所有实现PriorityOrdered接口的BeanFactoryPostProcessor // 对priorityOrderedPostProcessors排序 sortPostProcessors(priorityOrderedPostProcessors, beanFactory); // 遍历priorityOrderedPostProcessors, 执行postProcessBeanFactory办法 invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory); // Next, invoke the BeanFactoryPostProcessors that implement Ordered. // 调用所有实现Ordered接口的BeanFactoryPostProcessor List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); for (String postProcessorName : orderedPostProcessorNames) { // 获取postProcessorName对应的bean实例, 增加到orderedPostProcessors, 筹备执行 orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } // 对orderedPostProcessors排序 sortPostProcessors(orderedPostProcessors, beanFactory); // 遍历orderedPostProcessors, 执行postProcessBeanFactory办法 invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory); // Finally, invoke all other BeanFactoryPostProcessors. // 调用所有剩下的BeanFactoryPostProcessor List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); for (String postProcessorName : nonOrderedPostProcessorNames) { // 11.1 获取postProcessorName对应的bean实例, 增加到nonOrderedPostProcessors, 筹备执行 nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } // 遍历nonOrderedPostProcessors, 执行postProcessBeanFactory办法 invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory); // Clear cached merged bean definitions since the post-processors might have // modified the original metadata, e.g. replacing placeholders in values... // 革除元数据缓存（mergedBeanDefinitions、allBeanNamesByType、singletonBeanNamesByType）， // 因为后处理器可能曾经批改了原始元数据，例如， 替换值中的占位符... beanFactory.clearMetadataCache();}@1这里会咱们能够看下beanFactory中只有7个beanDefinition，其中只有ConfigurationClassPostProcessor是实现了BeanDefinitionRegistryPostProcessor接口
所以它会被优先执行。
ConfigurationClassPostProcessor后置处理器是在run()--->createApplicationContext()--->ApplicationContextFactory.create()--->
AnnotationConfigApplicationContext---->AnnotatedBeanDefinitionReader()--->
AnnotationConfigUtils.registerAnnotationConfigProcessors()增加的默认处理器。
@2因为加载了ConfigurationClassPostProcessor，零碎中可能新增一些实现了BeanDefinitionRegistryPostProcessor的类，对他们进行排序，遍历执行postProcessBeanDefinitionRegistry办法。
@3加载所有实现了BeanFactoryPostProcessor，执行postProcessBeanFactory办法
从代码执行的程序也能够晓得BeanDefinitionRegistryPostProcessor是在BeanFactoryPostProcessor之前执行
测试论证
@Componentpublic class BeanDefinitionRegistryPostProcessorOrder1 implements BeanDefinitionRegistryPostProcessor, Ordered { @Override public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException { System.out.println("BeanDefinitionRegistryPostProcessorOrder1:::"+"postProcessBeanDefinitionRegistry"); } @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { System.out.println("BeanDefinitionRegistryPostProcessorOrder1:::"+"postProcessBeanFactory"); } @Override public int getOrder() { return 1; }}@Componentpublic class BeanDefinitionRegistryPostProcessorOrder2 implements BeanDefinitionRegistryPostProcessor, Ordered { @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { System.out.println("BeanDefinitionRegistryPostProcessorOrder2:::" + "postProcessBeanFactory"); } @Override public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException { System.out.println("BeanDefinitionRegistryPostProcessorOrder2:::" + "postProcessBeanDefinitionRegistry"); } @Override public int getOrder() { return 2; }}@Componentpublic class BeanFactoryPostProcessorOrder1 implements BeanFactoryPostProcessor, Ordered { @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { System.out.println("BeanFactoryPostProcessorOrder1:::"+"postProcessBeanFactory"); } @Override public int getOrder() { return 1; }}@Componentpublic class BeanFactoryPostProcessorOrder2 implements BeanFactoryPostProcessor, Ordered { @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { System.out.println("BeanFactoryPostProcessorOrder2:::" + "postProcessBeanFactory"); } @Override public int getOrder() { return 2; }}输入后果：BeanDefinitionRegistryPostProcessorOrder1:::postProcessBeanDefinitionRegistryBeanDefinitionRegistryPostProcessorOrder2:::postProcessBeanDefinitionRegistryBeanDefinitionRegistryPostProcessorOrder1:::postProcessBeanFactoryBeanDefinitionRegistryPostProcessorOrder2:::postProcessBeanFactoryBeanFactoryPostProcessorOrder1:::postProcessBeanFactoryBeanFactoryPostProcessorOrder2:::postProcessBeanFactory