Spring5源码解析4-refresh方法之invokeBeanFactoryPostProcessors
2019-10-10 09:12
106 查看
invokeBeanFactoryPostProcessors(beanFactory);方法源码如下:
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) { // getBeanFactoryPostProcessors 获取的是 this.beanFactoryPostProcessors; //this.beanFactoryPostProcessors 只能通过 AbstractApplicationContext.addBeanFactoryPostProcessor 方法添加 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors()); // Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime // (e.g. through an @Bean method registered by ConfigurationClassPostProcessor) if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) { beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory)); beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader())); } }
getBeanFactoryPostProcessors()方法获取的是
AbstractApplicationContext#beanFactoryPostProcessors这个成员变量。
这个成员变量只能通过代码中手动编码调用
AbstractApplicationContext#addBeanFactoryPostProcessor方法来添加新的元素。很明显,我们这里为空。
invokeBeanFactoryPostProcessors(beanFactory)方法的主要的逻辑在
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors方法中:
//PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors())源码 public static void invokeBeanFactoryPostProcessors( ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) { // Invoke BeanDefinitionRegistryPostProcessors first, if any. Set<String> processedBeans = new HashSet<>(); if (beanFactory instanceof BeanDefinitionRegistry) { BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>(); List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>(); //beanFactoryPostProcessors是传进来里的对象,把传入的对象分类放入 BeanFactoryPostProcessor 和 BeanDefinitionRegistryPostProcessor //BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProcessor ,是一个特殊的 BeanFactoryPostProcessor for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) { if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) { BeanDefinitionRegistryPostProcessor registryProcessor = (BeanDefinitionRegistryPostProcessor) postProcessor; //如果传入的beanFactoryPostProcessors是它的子类,即:BeanDefinitionRegistryPostProcessor //则执行传入的BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry方法 registryProcessor.postProcessBeanDefinitionRegistry(registry); registryProcessors.add(registryProcessor); } else { regularPostProcessors.add(postProcessor); } } // Do noitialize 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. List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>(); // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered. //这里只能拿到spring内部的BeanDefinitionRegistryPostProcessor, //因为到这里spring还没有去扫描Bean,获取不到我们通过@Component标识的自定义BeanDefinitionRegistryPostProcessor //一般默认情况下,这里只有一个,BeanName:org.springframework.context.annotation.internalConfigurationAnnotationProcessor //对应的BeanClass:ConfigurationClassPostProcessor String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { //beanFactory.getBean, 这里开始创建BeanDefinitionRegistryPostProcessor bean 了 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); } } //排序 sortPostProcessors(currentRegistryProcessors, beanFactory); // registryProcessors 中放的是 BeanDefinitionRegistryPostProcessor // 因为这里只执行eanDefinitionRegistryPostProcessor中独有的方法,而不会执行其父类即BeanFactoryProcessor的方法 // 所以这里需要把处理器放入一个集合中,后续统一执行父类的方法 registryProcessors.addAll(currentRegistryProcessors); // 执行BeanDefinitionRegistryPostProcessor,currentRegistryProcessors中放的是spring内部的BeanDefinitionRegistryPostProcessor // 默认情况下,只有 org.springframework.context.annotation.ConfigurationClassPostProcessor // ConfigurationClassPostProcessor 里面就是在执行扫描Bean,并且注册BeanDefinition invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); // 清空这个临时变量,方便后面再使用 currentRegistryProcessors.clear(); // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered. // 这里已经可以获取到我们通过注册到Spring容器的 BeanDefinitionRegistryPostProcessor 了 postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { // 之前优先处理的是实现PriorityOrdered接口的,而PriorityOrdered接口也实现了Ordered接口 // 所有这里需要把之前已经处理过的给过滤掉 if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) { //之前这个临时变量已经被清空了,现在又开始放东西了 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); } } //排序 sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); // 执行BeanDefinitionRegistryPostProcessor invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); //清空临时变量 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) { //执行没有实现Ordered接口的BeanDefinitionRegistryPostProcessor 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(); } // Now, invoke the postProcessBeanFactory callback of all processors handled so far. // List<BeanDefinitionRegistryPostProcessor> registryProcessors // 之前已经执行过BeanDefinitionRegistryPostProcessor独有方法,现在执行其父类方法 invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); // List<BeanFactoryPostProcessor> regularPostProcessors // 执行 BeanFactoryPostProcessor 方法 invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); } else { // Invoke factory processors registered with the context instance. invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory); } // Do not initialize FactoryBeans here: We need to leave all regular beans // uninitialized to let the bean factory post-processors apply to them! // 获取 BeanFactoryPostProcessor 的 beanName String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false); // Separate between BeanFactoryPostProcessors that implement PriorityOrdered, // Ordered, and the rest. List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>(); List<String> orderedPostProcessorNames = new ArrayList<>(); List<String> nonOrderedPostProcessorNames = new ArrayList<>(); for (String ppName : postProcessorNames) { // 如果已经被执行过了,就不在执行 // 因为一开始先获取的BeanDefinitionRegistryPostProcessor,而BeanDefinitionRegistryPostProcessor继承了BeanFactoryPostProcessor 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. // 根据不同的优先级,按序执行 BeanFactoryPostProcessor sortPostProcessors(priorityOrderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory); // Next, invoke the BeanFactoryPostProcessors that implement Ordered. List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(); for (String postProcessorName : orderedPostProcessorNames) { orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } sortPostProcessors(orderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory); // Finally, invoke all other BeanFactoryPostProcessors. List<BeanFactoryPostProcessor> 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(); }
源码超级长,我们慢慢来看。
Spring容器使用的
BeanFactory
是DefaultListableBeanFactory
,它实现了BeanDefinitionRegistry
接口,if条件成立。优先处理程序传进来的
beanFactoryPostProcessors
,也就是我们手动调用AbstractApplicationContext#addBeanFactoryPostProcessor
方法来添加的BeanFactoryPostProcessor
。BeanFactoryPostProcessor
是一个顶级接口,他还有一个子类BeanDefinitionRegistryPostProcessor
。在该方法中声明了两个List
来存放BeanFactoryPostProcessor
和BeanDefinitionRegistryPostProcessor
,以便控制这两个接口方法的执行。遍历传入的
List<BeanFactoryPostProcessor> beanFactoryPostProcessors
,将其分类放到两个List
中。如果传入的是BeanDefinitionRegistryPostProcessor
类,则先执行BeanDefinitionRegistryPostProcessor
类中独有的方法postProcessBeanDefinitionRegistry
方法。当然,我们这里传入的List<BeanFactoryPostProcessor> beanFactoryPostProcessors
为空。第一次执行
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
方法,从容器中获取BeanDefinitionRegistryPostProcessor
类型的Bean的name(这里只是获取名称,还没有实例化Bean)。注意,程序执行到这里,Spring还没有扫描包,还没有将项目中的Bean注册到容器中。默认情况下,这里返回的数据为如下图所示。回忆一下,这个BeanDefinition
是在什么时候被加入到BeanFactory
的呢?是在AnnotationConfigApplicationContext
的无参构造器中创建reader
时注册的BeanDefinition
。其中BeanName为org.springframework.context.annotation.internalConfigurationAnnotationProcessor
,对应的Class为org.springframework.context.annotation.ConfigurationClassPostProcessor
。遍历这个获取的
postProcessorNames
,如果实现了PriorityOrdered
接口,就调用beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)
方法,从容器中获取这个Bean,将其加入到临时变量List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors
中。对
currentRegistryProcessors
中的元素进行排序,然后执行BeanDefinitionRegistryPostProcessor
中的特有方法postProcessBeanDefinitionRegistry
。注意哦,这里没有执行其父类的方法,而是又将其放到List<BeanDefinitionRegistryPostProcessor> registryProcessors
中,到后面再执行其父类方法。默认情况下,此时
currentRegistryProcessors
中只有一个Bean即:org.springframework.context.annotation.ConfigurationClassPostProcessor
(它实现了PriorityOrdered
接口)。ConfigurationClassPostProcessor
是一个非常重要的类,我们后面在讲。当程序执行完ConfigurationClassPostProcessor
的BeanDefinitionRegistryPostProcessor
方法后,我们程序中的Bean就被注册到了Spring容器中了,需要注意的是,这里还只是注册了BeanDefinition
,还没有创建Bean对象。当第二次执行
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
方法,此时因为之前已经完成了Bean的扫描,所以如果我们有自定义的BeanDefinitionRegistryPostProcessor
就可以在这里被获取了。获取之前,判断其是否实现Ordered
接口,并且之前没有被执行过,则调用getBean
方法,从容器中获取该Bean,然后进行排序,执行postProcessBeanDefinitionRegistry
方法。前面已经按顺序执行了实现
PriorityOrdered
和Ordered
接口的BeanDefinitionRegistryPostProcessor
,最后,执行没有实现Ordered
接口的BeanDefinitionRegistryPostProcessor
的postProcessBeanDefinitionRegistry
方法。执行完之后再BeanDefinitionRegistryPostProcessor
的父类方法postProcessBeanFactory
。获取容器中还没有被执行过的实现
BeanFactoryPostProcessor
接口的Bean,然后按顺序执行的postProcessBeanFactory
。默认情况下,这里会获取到:
由于Bean
org.springframework.context.annotation.internalConfigurationAnnotationProcessor(对应的Class为
org.springframework.context.annotation.ConfigurationClassPostProcessor)在之前已经被执行了,这里只会执行Bean
org.springframework.context.event.internalEventListenerProcessor(对应的Class为
org.springframework.context.event.EventListenerMethodProcessor)的
postProcessBeanFactory方法,源码如下:
//org.springframework.context.event.EventListenerMethodProcessor#postProcessBeanFactory 源码 @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { this.beanFactory = beanFactory; Map<String, EventListenerFactory> beans = beanFactory.getBeansOfType(EventListenerFactory.class, false, false); List<EventListenerFactory> factories = new ArrayList<>(beans.values()); AnnotationAwareOrderComparator.sort(factories); this.eventListenerFactories = factories; }
未完待续......
源码学习笔记:https://github.com/shenjianeng/spring-code-study
欢迎关注公众号:
相关文章推荐
- Spring IOC源码解析--invokeBeanFactoryPostProcessors控制后置处理器的bean加载顺序
- Spring源码情操陶冶-AbstractApplicationContext#invokeBeanFactoryPostProcessors
- Spring源码分析之BeanPostProcessor接口和BeanFactoryPostProcessor接口方法不执行原因分析
- Spring源码解析笔记9——容器的功能扩展BeanFactory的后处理(BeanFactoryPostProcessor)
- spring初始化refresh()方法中obtainFreshBeanFactory()源码走读。
- Spring源码分析之BeanPostProcessor接口和BeanFactoryPostProcessor接口方法不执行原因分析
- 解析Spring源码(2)---new XmlBeanFactory(new ClassPathResource("..."))
- 【SSH进阶之路】Spring的IOC逐层深入——源码解析之IoC的根本BeanFactory(五)
- Spring 源码梳理(四) BeanFactoryPostProcessor
- Spring BeanFactory源码解析
- Spring源码学习--BeanFactoryPostProcessor
- 【SSH进阶之路】Spring的IOC逐层深入——源码解析之IoC的根本BeanFactory(五)
- 【Spring源码解析】—— 简单工厂模式的BeanFactory的超简版实现
- Spring源码解析——start from BeanFactory(一)
- Spring源码解析 - ListableBeanFactory
- 【SSH进阶之路】Spring的IOC逐层深入——源码解析之IoC的根本BeanFactory(五)
- Spring的IOC逐层深入——源码解析之IoC的根本BeanFactory(五)
- 做一个合格的程序猿之浅析Spring IoC源码(六)BeanFactoryPostProcessor
- Spring 源码阅读 BeanFactory(二) 之registerBeanDefinition方法