文章目录

• Spring源码系列：
• 前言
• 正文
• • 方法1：finishRefresh
  • 方法2：initLifecycleProcessor
  • 方法3：onRefresh
  • 方法4：publishEvent
  • 方法5：multicastEvent
  • 方法6：invokeListener
  • 方法7：doInvokeListener
• 总结

Spring源码系列：

Spring IOC源码：简单易懂的Spring IOC 思路介绍
Spring IOC源码：核心流程介绍
Spring IOC源码：ApplicationContext刷新前准备工作
Spring IOC源码：obtainFreshBeanFactory 详解（上）
Spring IOC源码：obtainFreshBeanFactory 详解（中）
Spring IOC源码：obtainFreshBeanFactory 详解（下）
Spring IOC源码：＜context:component-scan＞源码详解
Spring IOC源码：invokeBeanFactoryPostProcessors 后置处理器详解
Spring IOC源码：registerBeanPostProcessors 详解
Spring IOC源码：实例化前的准备工作
Spring IOC源码：finishBeanFactoryInitialization详解
Spring IoC源码：getBean 详解
Spring IoC源码：createBean（ 上）
Spring IoC源码：createBean（ 中）
Spring IoC源码：createBean（ 下）
Spring IoC源码：finishRefresh 完成刷新详解

前言

当完成Bean定义信息解析、Bean的创建、初始化流程之后，到最后一个方法finishRefresh完成上下文刷新。

正文

来到refresh()方法中的最后一个方法finishRefresh();

public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {// 容器刷新前准备工作prepareRefresh();// Tell the subclass to refresh the internal bean factory.//创建Bean工厂，解析配置ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();// bean工厂准备工作prepareBeanFactory(beanFactory);try {//拓展接口，留给子类进行实现拓展postProcessBeanFactory(beanFactory);// 注册执行，BeanFactoryPostProcessorinvokeBeanFactoryPostProcessors(beanFactory);// 注册创建BeanPostProcessorregisterBeanPostProcessors(beanFactory);// 这个方法主要作用就是使用国际化，定制不同的消息文本，比如定义了一个Person的Bean，它有name属性，我们需要在不同的国家展示对应国家所在语言名称，这时候就可以使用国际化了。initMessageSource();// Initialize event multicaster for this context.//初始化应用事件广播器initApplicationEventMulticaster();// Initialize other special beans in specific context subclasses.//拓展接口，留给子类进行实现拓展，springboot就对该方法进行了处理onRefresh();// Check for listener beans and register them.//将内部的、以及我们自定义的监听器添加到缓存中，为后续逻辑处理做准备。还有添加事件源到缓存中。registerListeners();// Instantiate all remaining (non-lazy-init) singletons.//实例化剩下非懒加载的BeanfinishBeanFactoryInitialization(beanFactory);// Last step: publish corresponding event.//使用应用事件广播器推送上下文刷新完毕事件（ContextRefreshedEvent ）到相应的监听器。finishRefresh();}catch (BeansException ex) {if (logger.isWarnEnabled()) {logger.warn("Exception encountered during context initialization - " +"cancelling refresh attempt: " + ex);}// Destroy already created singletons to avoid dangling resources.//执行相关销毁方法destroyBeans();// Reset 'active' flag.//重置上下文刷新状态cancelRefresh(ex);// Propagate exception to caller.throw ex;}finally {// Reset common introspection caches in Spring's core, since we// might not ever need metadata for singleton beans anymore...resetCommonCaches();}}}

finishRefresh()，见方法1详解

方法1：finishRefresh

	protected void finishRefresh() {// Clear context-level resource caches (such as ASM metadata from scanning).//清除该资源加载器中的所有资源缓存clearResourceCaches();// Initialize lifecycle processor for this context.//初始化LifecycleProcessor。initLifecycleProcessor();// Propagate refresh to lifecycle processor first.//调用LifecycleProcessor的onRefresh方法进行刷新getLifecycleProcessor().onRefresh();// 发布事件publishEvent(new ContextRefreshedEvent(this));// Participate in LiveBeansView MBean, if active.LiveBeansView.registerApplicationContext(this);}

initLifecycleProcessor()，见方法2详解

getLifecycleProcessor().onRefresh()，见方法3详解

publishEvent(new ContextRefreshedEvent(this))，见方法4详解

方法2：initLifecycleProcessor

	protected void initLifecycleProcessor() {//获取BeanFactory工厂ConfigurableListableBeanFactory beanFactory = getBeanFactory();//判断是否存在名称为lifecycleProcessor的Bean或定义信息if (beanFactory.containsLocalBean(LIFECYCLE_PROCESSOR_BEAN_NAME)) {//获取或创建LifecycleProcessorthis.lifecycleProcessor =beanFactory.getBean(LIFECYCLE_PROCESSOR_BEAN_NAME, LifecycleProcessor.class);if (logger.isTraceEnabled()) {logger.trace("Using LifecycleProcessor [" + this.lifecycleProcessor + "]");}}else {//bean工厂中不存在该bean的信息，则创建一个默认的DefaultLifecycleProcessor defaultProcessor = new DefaultLifecycleProcessor();defaultProcessor.setBeanFactory(beanFactory);this.lifecycleProcessor = defaultProcessor;//注册添加到一级缓存中beanFactory.registerSingleton(LIFECYCLE_PROCESSOR_BEAN_NAME, this.lifecycleProcessor);if (logger.isTraceEnabled()) {logger.trace("No '" + LIFECYCLE_PROCESSOR_BEAN_NAME + "' bean, using " +"[" + this.lifecycleProcessor.getClass().getSimpleName() + "]");}}}

方法3：onRefresh

	public void onRefresh() {startBeans(true);this.running = true;}

private void startBeans(boolean autoStartupOnly) {//获取Lifecycle类型的bean集合Map lifecycleBeans = getLifecycleBeans();Map phases = new HashMap<>();lifecycleBeans.forEach((beanName, bean) -> {//autoStartupOnly 为true时，代表是容器自动启动调用，这时只有SmartLifecycle 类型且isAutoStartup为TRUE才会调用//如果autoStartupOnly 为false，代表是手动调用，会调用所有的Lifecycleif (!autoStartupOnly || (bean instanceof SmartLifecycle && ((SmartLifecycle) bean).isAutoStartup())) {//获取阶段值，即优先级值。如果有实现Phased接口，则通过getPhase方法返回数值，值越小则排序越前int phase = getPhase(bean);//判断容器中是否已存在，不存在则创建LifecycleGroup 类型对象LifecycleGroup group = phases.get(phase);if (group == null) {group = new LifecycleGroup(phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly);phases.put(phase, group);}group.add(beanName, bean);}});if (!phases.isEmpty()) {List keys = new ArrayList<>(phases.keySet());//排序Collections.sort(keys);//遍历调用for (Integer key : keys) {phases.get(key).start();}}}

方法4：publishEvent

protected void publishEvent(Object event, @Nullable ResolvableType eventType) {Assert.notNull(event, "Event must not be null");// Decorate event as an ApplicationEvent if necessary//判断事件是否继承了ApplicationEvent接口ApplicationEvent applicationEvent;if (event instanceof ApplicationEvent) {applicationEvent = (ApplicationEvent) event;}else {//将事件封装成PayloadApplicationEvent类型的事件applicationEvent = new PayloadApplicationEvent<>(this, event);//设置事件类型if (eventType == null) {eventType = ((PayloadApplicationEvent) applicationEvent).getResolvableType();}}// Multicast right now if possible - or lazily once the multicaster is initializedif (this.earlyApplicationEvents != null) {this.earlyApplicationEvents.add(applicationEvent);}else {//使用多播器发布事件getApplicationEventMulticaster().multicastEvent(applicationEvent, eventType);}// Publish event via parent context as well...//使用父上下文进行发布事件if (this.parent != null) {if (this.parent instanceof AbstractApplicationContext) {((AbstractApplicationContext) this.parent).publishEvent(event, eventType);}else {this.parent.publishEvent(event);}}}

getApplicationEventMulticaster().multicastEvent(applicationEvent, eventType)，见方法5详解

方法5：multicastEvent

	public void multicastEvent(final ApplicationEvent event, @Nullable ResolvableType eventType) {//获取事件源类型ResolvableType type = (eventType != null ? eventType : resolveDefaultEventType(event));Executor executor = getTaskExecutor();//根据事件类型获取对应类型的监听器for (ApplicationListener listener : getApplicationListeners(event, type)) {//调用监听器的onApplicationEvent方法if (executor != null) {executor.execute(() -> invokeListener(listener, event));}else {invokeListener(listener, event);}}}

invokeListener(listener, event))，见方法6详解

方法6：invokeListener

	protected void invokeListener(ApplicationListener listener, ApplicationEvent event) {//获取错误处理器ErrorHandler errorHandler = getErrorHandler();if (errorHandler != null) {try {//调用监听器处理方法doInvokeListener(listener, event);}catch (Throwable err) {errorHandler.handleError(err);}}else {doInvokeListener(listener, event);}}

doInvokeListener(listener, event)，见方法7详解

方法7：doInvokeListener

private void doInvokeListener(ApplicationListener listener, ApplicationEvent event) {try {//调用监听器的onApplicationEvent方法，并传入事件listener.onApplicationEvent(event);}catch (ClassCastException ex) {String msg = ex.getMessage();if (msg == null || matchesClassCastMessage(msg, event.getClass())) {// Possibly a lambda-defined listener which we could not resolve the generic event type for// -> let's suppress the exception and just log a debug message.Log logger = LogFactory.getLog(getClass());if (logger.isTraceEnabled()) {logger.trace("Non-matching event type for listener: " + listener, ex);}}else {throw ex;}}}

总结

Spring IOC中refresh()所有方法都讲解完了，这里面的内容非车多，花了不少时间在看，但是感觉还是比较粗糙，文章中有很多点理解得不是很到位，如果大家有更好的见解，欢迎指点评论。学习IOC过程是非常枯燥的，但是耐心去看真的能发现这个框架设计真的很厉害，拓展性做得很好，有很多地方值得我们在工作中进行参考开发。后续会发布Spring 系列的其它文章，如AOP，只有不断的学习，才能加深对Spring框架的理解。