Spring invokeBeanFactoryPostProcessors方法刨析源码
概述
invokeBeanFactoryPostProcessor方法是spring核心方法之一,主要用来调用beanFactory后置处理器来修改beanDefinition。
该方法实例化并调用已经注册到beanFactory的beanFactoryPostProcessor实例。
invokeBeanFactoryPostProcessors
/** * 实例化并且调用所有已经注册了的beanFactoryPostProcessor,遵循指明的顺序 * * Instantiate and invoke all registered BeanFactoryPostProcessor beans, * respecting explicit order if given. * <p>Must be called before singleton instantiation. */ protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) { // 获取到当前应用程序上下文的beanFactoryPostProcessors变量的值,并且实例化调用执行所有已经注册的beanFactoryPostProcessor // 默认情况下,通过getBeanFactoryPostProcessoandroidrs()来获取已经注册的BFPP,但是默认是空的 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors()); // Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime // (e.g. through an @Bean method registered by ConfigurationClassPostProcess编程客栈or) if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) { beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory)); beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader())); } }
getBeanFactoryPostProcessors() 方法
方法获取自定义的BFPP方法,默认为空。
// TODO 如何设置自定义的BFPP?
invokeBeanFactoryPostProcessors方法
public static void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory,
List beanFactoryPostProcessors){}
参数:ConfigurableListableBeanFactory beanFactory是refresh()方法中的obtainFreshBeanFactory()方法获取的。
是DefaultListableBeanFactory 类型,DefaultListableBeanFactory类实现了BeanDefinitionRegistry接口。
public final ConfigurableListableBeanFactory getBeanFactory() { DefaultListableBeanFactory beanFactory = this.beanFactory; if (beanFactory == null) { throw new IllegalStateException("BeanFactory not initialized or already closed - " + "call 'refresh' before Accessing beans via the ApplicationContext"); } return beanFactory; }
所以会走下面分支
if (beanFactory instanceof BeanDefinitionRegistry) { ... }
否则直接调用外部beanFactoryPostProcessors的postProcessBeanFactory方法。
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
BeanFactoryPostProcessor和BeanDefinitionRegistryPostProcessor分类
// 类型转换 BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; // 此处希望大家做一个区分,两个接口是不同的,BeanDefinitionRegistryPostProcessor是BeanFactoryPostProcessor的子集 // BeanFactoryPostProcessor主要针对的操作对象是BeanFactory,而BeanDefinitionRegistryPostProcessor主要针对的操作对象是BeanDefinition // 存放BeanFactoryPostProcessor的集合 List<BeanFactoryPost开发者_JAVA教程Processor> regularPostProcessors = new ArrayList<>(); // 存放BeanDefinitionRegistryPostProcessor的集合 List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>(); // 首先处理入参中的beanFactoryPostProcessors,遍历所有的beanFactoryPostProcessors,将BeanDefinitionRegistryPostProcessor // 和BeanFactoryPostProcessor区分开 for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) { // 如果是BeanDefinitionRegistryPostProcessor if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) { BeanDefinitionRegistryPostProcessor registryProcessor = (BeanDefinitionRegistryPostProcessor) postProcessor; // 直接执行BeanDefinitionRegistryPostProcessor接口中的postProcessBeanDefinitionRegistry方法 registryProcessor.postProcessBeanDefinitionRegistry(registry); // 添加到registryProcessors,用于后续执行postProcessBeanFactory方法 registryProcessors.add(registryProcessor); } else { // 否则,只是普通的BeanFactoryPostProcessor,添加到regularPostProcessors,用于后续执行postProcessBeanFactory方法 regularPostProcessors.add(postProcessor); } }
处理实现了PriorityOrdered接口的BeanDefinitionRegistryPostProcessor类
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>(); // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered. // 调用所有实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessor实现类 // 找到所有实现BeanDefinitionRegistryPostProcessor接口bean的beanName String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); // 遍历处理所有符合规则的postProcessorNames for (String ppName : postProcessorNames) { // 检测是否实现了PriorityOrdered接口 if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { // 获取名字对应的bean实例,添加到currentRegistryProcessors中 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); // 将要被执行的BFPP名称添加到processedBeans,避免后续重复执行 processedBeans.add(ppName); } } // 按照优先级进行排序操作 sortPostProcessors(currentRegistryProcessors, beanFactory); // 添加到registryProcessors中,用于最后执行postProcessBeanFactory方法 registryProcessors.addAll(currentRegistryProcessors); // 遍历currentRegistryProcessors,执行postProcessBeanDefinitionRegistry方法 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); // 执行完毕之后,清空currentRegistryProcessors currentRegistryProcessors.clear();
处理实现了Ordered的BeanDefinitionRegistryPostProcessor类
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { // 检测是否实现了Ordered接口,并且还未执行过 if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) { // 获取名字对应的bean实例,添加到currentRegistryProcessors中 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); // 将要被执行的BFPP名称添加到processedBeans,避免后续重复执行 processedBeans.add(ppName); } } // 按照优先级进行排序操作 sortPostProcessors(currentRegistryProcessors, beanFactory); // 添加到registryProcessors中,用于最后执行postProcessBeanFactory方法 registryProcessors.addAll(currentRegistryProcessors); // 遍历currentRegistryProcessors,执行postProcessBeanDefinitionRegistry方法 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); // 执行完毕之后,清空currentRegistryProcessors currentRegistryProcessors.clear();
处理剩下的BeanDefinitionRegistryPostProcessor类
// 最后,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); // 遍历执行 for (String ppName : postProcessorNames) { // 跳过已经执行过的BeanDefinitionRegistryPostProcessor if (!processedBeans.contains(ppName)) { // 获取名字对应的bean实例,添加到currentRegistryProcessors中 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); // 将要被执行的BFPP名称添加到processedBeans,避免后续重复执行 processedBeans.add(ppName); reiterate = true; } } // 按照优先级进行排序操作 sortPostProcessors(currentRegistryProcessors, beanFactory); // 添加到registryProcessors中,用于最后执行postProcessBeanFactory方法 registryProcessors.addAll(currentRegistryProcessors); // 遍历currentRegistryProcessors,执行postProcessBeanDefinitionRegistry方法 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); // 执行完毕之后,清空currentRegistryProcessors currentRegistryProcessors.clear(); }
注意这里的reiterate变量在每找到一个未执行的BeanDefinitionRegistryPostProcessor实例都会被设置为true,表示invokeBephpanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);方法执行时可能会生成新的BeanDefinitionRegistryPostProcessophpr实例。
调用所有BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法
// 调用所有BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法 invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); // 最后,调用入参beanFactoryPostProcessors中的普通BeanFactoryPostProcessor的postProcessBeanFactory方法 invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
处理BeanFactory容器中注册的BeanFactoryPostProcessor类
处理方式与上面处理BeanDefinitionRegistryPostProcessor类似,按照先后顺序分别处理实现了PriorityOrdered接口、Ordered接口、没有实现Ordered接口的bean。这里不在详细说明。
// 到这里为止,入参beanFactoryPostProcessors和容器中的所有BeanDefinitionRegistryPostProcessor已经全部处理完毕,下面开始处理容器中 编程 // 所有的BeanFactoryPostProcessor // 可能会包含一些实现类,只实现了BeanFactoryPostProcessor,并没有实现BeanDefinitionRegistryPostProcessor接口, // 因为有processedBeans记录了上面处理的实现了BeanDefinitionRegistryPostProcessor的类,所以不会重复处理。 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false); regularPostProcessors = new ArrayList(); registryProcessors = new ArrayList(); currentRegistryProcessors = new ArrayList(); postProcessorNames = postProcessorNames; int var20 = postProcessorNames.length; String ppName; for(var9 = 0; var9 < var20; ++var9) { ppName = postProcessorNames[var9]; if (!processedBeans.contains(ppName)) { if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { regularPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class)); } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) { registryProcessors.add(ppName); } else { currentRegistryProcessors.add(ppName); } } } sortPostProcessors(regularPostProcessors, beanFactory); invokeBeanFactoryPostProcessors((Collection)regularPostProcessors, (ConfigurableListableBeanFactory)beanFactory); List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList(); Iterator var21 = registryProcessors.iterator(); while(var21.hasNext()) { String postProcessorName = (String)var21.next(); orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } sortPostProcessors(orderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors((Collection)orderedPostProcessors, (ConfigurableListableBeanFactory)beanFactory); List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList(); Iterator var24 = currentRegistryProcessors.iterator(); while(var24.hasNext()) { ppName = (String)var24.next(); nonOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class)); } invokeBeanFactoryPostProcessors((Collection)nonOrderedPostProcessors, (ConfigurableListableBeanFactory)beanFactory); // 因为后置处理器可能已经修改了原始元数据,例如,替换值中的占位符 beanFactory.clearMetadataCache();
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