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AbstractApplicationContext是对ApplicationContext的第一个实现:

看一下他的几个核心结构:

/** BeanFactoryPostProcessor列表,在bean的创建过程中可以对bean进行进一步的加工 */private final List
   
     beanFactoryPostProcessors = new ArrayList<>();//生命周期流程,可以接收到整个应用启动,停止,将要刷新和将要关闭private LifecycleProcessor lifecycleProcessor;//消息,支持国际化等private MessageSource messageSource;//事件广播器private ApplicationEventMulticaster applicationEventMulticaster;
   

在各种bean定义加载完成后,都需要对ApplicationContext进行刷新,对bean工厂的各种配置以及bean的创建等都是在这个流程中执行的,

我们重点看一下refresh方法:

// Prepare this context for refreshing.prepareRefresh();// Tell the subclass to refresh the internal bean factory.ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();// Prepare the bean factory for use in this context.prepareBeanFactory(beanFactory);try {// Allows post-processing of the bean factory in context subclasses.postProcessBeanFactory(beanFactory);// Invoke factory processors registered as beans in the context.invokeBeanFactoryPostProcessors(beanFactory);// Register bean processors that intercept bean creation.registerBeanPostProcessors(beanFactory);// Initialize message source for this context.initMessageSource();// Initialize event multicaster for this context.initApplicationEventMulticaster();// Initialize other special beans in specific context subclasses.onRefresh();// Check for listener beans and register them.registerListeners();// Instantiate all remaining (non-lazy-init) singletons.finishBeanFactoryInitialization(beanFactory);// Last step: publish corresponding event.finishRefresh();

接下来逐个方法看一下:

prepareRefresh:一些启动参数的设置 prepareBeanFactory:对bean工厂的准备配置,咱们自己使用bean工厂的话,可以参照这里

//类加载器beanFactory.setBeanClassLoader(getClassLoader());//表达式解析器beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));//属性资源注册beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));//设置ApplicationContext的后处理器beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));//下面是一些解析时忽略的接口,这些资源在ApplicationContext刷新过程中已经创建,只需要注入即可beanFactory.ignoreDependencyInterface(EnvironmentAware.class);beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);beanFactory.ignoreDependencyInterface(MessageSourceAware.class);beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);//这些资源在ApplicationContext刷新过程中已经创建,都是可以解析资源beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);beanFactory.registerResolvableDependency(ResourceLoader.class, this);beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);beanFactory.registerResolvableDependency(ApplicationContext.class, this);//后处理器,能够对实现了事件监听的接口注册到事件广播中beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));// LoadTimeWeaver功能支持if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {	beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));	// Set a temporary ClassLoader for type matching.	beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));}//注册环境先关的单列if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {	beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());}if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {	beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());}if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {	beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());}

postProcessBeanFactory:给子类一个参与工厂post的机会,比如在Servlet中:

//添加了一些后处理器,以及注册了各种web相关的scope,以及环境@Overrideprotected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {	if (this.servletContext != null) {		beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext));		beanFactory.ignoreDependencyInterface(ServletContextAware.class);	}	WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);	WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext);}

invokeBeanFactoryPostProcessors:实例化并且执行所有的BeanFactoryPostProcessors流程,实现了该接口的对象,

可以在任何bean实例化前,对bean工厂,做进一步的加工处理 registerBeanPostProcessors:对bean工厂注册BeanPostProcessors,注册顺序,先注册PriorityOrdered,然后Ordered,然后其他未实现order的 看一下源码:

String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);// First, register the BeanPostProcessors that implement PriorityOrdered.sortPostProcessors(priorityOrderedPostProcessors, beanFactory);registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);// Next, register the BeanPostProcessors that implement Ordered.sortPostProcessors(orderedPostProcessors, beanFactory);registerBeanPostProcessors(beanFactory, orderedPostProcessors);// Now, register all regular BeanPostProcessors.registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);

initMessageSource:初始化MessageSource,没有的话委托给父容器

initApplicationEventMulticaster:初始化事件广播 onRefresh:通知子类,将要刷新,子类执行必要操作 registerListeners:注册事件监听器到广播器上 finishBeanFactoryInitialization:实例化单列bean finishRefresh:

clearResourceCaches();// Initialize lifecycle processor for this context.initLifecycleProcessor();// Propagate refresh to lifecycle processor first.getLifecycleProcessor().onRefresh();// Publish the final event.publishEvent(new ContextRefreshedEvent(this));// Participate in LiveBeansView MBean, if active.LiveBeansView.registerApplicationContext(this);

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