AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext();
// ......
applicationContext.refresh();

public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			// 啟動(dòng)前的準(zhǔn)備工作：記錄啟動(dòng)時(shí)間，活動(dòng)標(biāo)記為啟動(dòng)以及環(huán)境屬性變量集合的初始化
			prepareRefresh();
			// Tell the subclass to refresh the internal bean factory.
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
			// Prepare the bean factory for use in this context.
			//還是一些準(zhǔn)備工作，添加了兩個(gè)后置處理器：ApplicationContextAwareProcessor，ApplicationListenerDetector
			//還設(shè)置了 忽略自動(dòng)裝配 和 允許自動(dòng)裝配 的接口
			//對(duì)環(huán)境，系統(tǒng)環(huán)境，系統(tǒng)屬性三個(gè)Bean如果不存在某個(gè)bean的時(shí)候，spring就自動(dòng)生成singleton bean（Not bd）
			//還設(shè)置了bean表達(dá)式解析器 等
			prepareBeanFactory(beanFactory);
			try {
				// Allows post-processing of the bean factory in context subclasses.
				// 空方法
				postProcessBeanFactory(beanFactory);
				// Invoke factory processors registered as beans in the context.
				//執(zhí)行自定義的BeanFactoryProcessor和內(nèi)置的BeanFactoryProcessor
				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();
			}
			finally {
				// Reset common introspection caches in Spring's core, since we
				// might not ever need metadata for singleton beans anymore...
				resetCommonCaches();
			}
		}
	}

	protected void prepareRefresh() {
		// Switch to active.
		this.startupDate = System.currentTimeMillis();
		this.closed.set(false);
		this.active.set(true);
		// Initialize any placeholder property sources in the context environment.
		// 空方法
		initPropertySources();
		// Validate that all properties marked as required are resolvable:
		// see ConfigurablePropertyResolver#setRequiredProperties
		getEnvironment().validateRequiredProperties();
		// Store pre-refresh ApplicationListeners...
		if (this.earlyApplicationListeners == null) {
			this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
		}
		else {
			// Reset local application listeners to pre-refresh state.
			this.applicationListeners.clear();
			this.applicationListeners.addAll(this.earlyApplicationListeners);
		}
		// Allow for the collection of early ApplicationEvents,
		// to be published once the multicaster is available...
		this.earlyApplicationEvents = new LinkedHashSet<>();
	}

protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
		// CAS保證同步
		refreshBeanFactory();
		// 返回beanFactory- DefaultListableBeanFactory.class
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		return beanFactory;
	}

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory)  {
    	// Tell the internal bean factory to use the context's class loader etc.
		beanFactory.setBeanClassLoader(getClassLoader());
		//設(shè)置bean表達(dá)式解析器
		beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		//屬性編輯器支持
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// Configure the bean factory with context callbacks.
		//添加一個(gè)后置處理器：ApplicationContextAwareProcessor，此后置處理處理器實(shí)現(xiàn)了BeanPostProcessor接口
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
		//以下接口，忽略自動(dòng)裝配
		beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
   		// .....
    	// BeanFactory interface not registered as resolvable type in a plain factory.
		// MessageSource registered (and found for autowiring) as a bean.
		//以下接口，允許自動(dòng)裝配,第一個(gè)參數(shù)是自動(dòng)裝配的類型，，第二個(gè)字段是自動(dòng)裝配的值
		// 這個(gè)接口僅會(huì)將注入的參數(shù)XXX.class注入為指定的值，但不影響XXX.class創(chuàng)建Bean對(duì)象；
		beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
		beanFactory.registerResolvableDependency(ResourceLoader.class, this);
    	// Register default environment beans.
		// 環(huán)境，系統(tǒng)環(huán)境，系統(tǒng)屬性 因此通常情況下，這三個(gè)Bean是沒(méi)有bd的
		//如果沒(méi)有注冊(cè)過(guò)bean名稱為XXX，spring就自己創(chuàng)建一個(gè)名稱為XXX的singleton bean
		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());
		}
}

protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
	// getBeanFactoryPostProcessors是spring允許我們手動(dòng)添加BeanFactoryPostProcessor
	// 即：annotationConfigApplicationContext.addBeanFactoryPostProcessor(XXX);
    // 未手動(dòng)添加的話，getBeanFactoryPostProcessors()為empty
		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()));
		}
	}

public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPostProcessor,
		PriorityOrdered, ResourceLoaderAware, BeanClassLoaderAware, EnvironmentAware {}

public static void invokeBeanFactoryPostProcessors(
			ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {

		// Invoke BeanDefinitionRegistryPostProcessors first, if any.
		Set<String> processedBeans = new HashSet<>();

		// 如果不是BeanDefinitionRegistry 則直接執(zhí)行beanFactoryPostProcessors
		// 剛啟動(dòng)時(shí)傳入的beanFactory是DefaultListableBeanFactory，他是實(shí)現(xiàn)了BeanDefinitionRegistry 因此會(huì)走這里
		if (beanFactory instanceof BeanDefinitionRegistry) {
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
			// bf后置處理器集合（手動(dòng)添加與bdr后置處理器集合【下面的那個(gè)集合】）：因?yàn)閎drp屬于bfp
			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
			// bdr后置處理器集合（手動(dòng)添加與spring自己的）
			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();

			// 循環(huán)傳進(jìn)來(lái)的beanFactoryPostProcessors，剛啟動(dòng)時(shí)未手動(dòng)增加的情況下beanFactoryPostProcessors肯定沒(méi)有數(shù)據(jù)
			// 因?yàn)閎eanFactoryPostProcessors是獲得手動(dòng)添加的，而不是spring掃描的
			// 只有手動(dòng)調(diào)用annotationConfigApplicationContext.addBeanFactoryPostProcessor(XXX)才會(huì)有數(shù)據(jù)
			// 執(zhí)行手動(dòng)添加的beanFactoryPostProcessors， 如果是BeanDefinitionRegistryPostProcessor，則執(zhí)行其postProcessBeanDefinitionRegistry再加到list中
			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;
					registryProcessor.postProcessBeanDefinitionRegistry(registry);
					registryProcessors.add(registryProcessor);
				}
				else {
					regularPostProcessors.add(postProcessor);
				}
			}
			//一個(gè)臨時(shí)變量，用來(lái)裝載BeanDefinitionRegistryPostProcessor為了排序
			//BeanDefinitionRegistry繼承了PostProcessorBeanFactoryPostProcessor
			List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

			// 獲得實(shí)現(xiàn)BeanDefinitionRegistryPostProcessor接口的類
			// 就是ConfigurationClassPostProcessor（Spring自己添加的-在reader()時(shí)增加的）
			String[] postProcessorNames =
					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
					//獲得ConfigurationClassPostProcessor類，并且放到currentRegistryProcessors
					//ConfigurationClassPostProcessor是很重要的一個(gè)類，它實(shí)現(xiàn)了BeanDefinitionRegistryPostProcessor接口
					//BeanDefinitionRegistryPostProcessor接口又實(shí)現(xiàn)了BeanFactoryPostProcessor接口
					//ConfigurationClassPostProcessor是極其重要的類
					//里面執(zhí)行了掃描Bean，Import，ImportResouce等各種操作
					//用來(lái)處理配置類（有兩種情況 一種是傳統(tǒng)意義上的配置類，一種是普通的bean）的各種邏輯
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					//把name放到processedBeans，后續(xù)會(huì)根據(jù)這個(gè)集合來(lái)判斷處理器是否已經(jīng)被執(zhí)行過(guò)了
					processedBeans.add(ppName);
				}
			}
			//處理排序
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			//合并Processors，為什么要合并，因?yàn)閞egistryProcessors是裝載BeanDefinitionRegistryPostProcessor的
			//一開(kāi)始的時(shí)候，spring只會(huì)執(zhí)行BeanDefinitionRegistryPostProcessor獨(dú)有的方法
			//而不會(huì)執(zhí)行BeanDefinitionRegistryPostProcessor父類的方法，即BeanFactoryProcessor的方法
			//所以這里需要把處理器放入一個(gè)集合中，后續(xù)統(tǒng)一執(zhí)行父類的方法
			registryProcessors.addAll(currentRegistryProcessors);
			//可以理解為執(zhí)行ConfigurationClassPostProcessor的postProcessBeanDefinitionRegistry方法
			//Spring熱插播的體現(xiàn)，像ConfigurationClassPostProcessor就相當(dāng)于一個(gè)組件，Spring很多事情就是交給組件去管理
			//將spring提供的RegistryProcessors(就是這個(gè)ConfigurationClassPostProcessor)執(zhí)行其postProcessBeanDefinitionRegistry
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			//清空臨時(shí)變量
			currentRegistryProcessors.clear();
			// 再次根據(jù)BeanDefinitionRegistryPostProcessor獲得BeanName，看這個(gè)BeanName是否已經(jīng)被執(zhí)行過(guò)了，有沒(méi)有實(shí)現(xiàn)Ordered接口
			// 如果沒(méi)有被執(zhí)行過(guò)，也實(shí)現(xiàn)了Ordered接口的話，把對(duì)象推送到currentRegistryProcessors，名稱推送到processedBeans
			// 如果沒(méi)有實(shí)現(xiàn)Ordered接口的話，這里不把數(shù)據(jù)加到currentRegistryProcessors，processedBeans中，后續(xù)再做處理
			// 這里才可以獲得我們定義的實(shí)現(xiàn)了BeanDefinitionRegistryPostProcessor的Bean
			postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			//處理排序
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			//合并Processors
			registryProcessors.addAll(currentRegistryProcessors);
			//執(zhí)行有Ordered的BeanDefinitionRegistryPostProcessor
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			//清空臨時(shí)變量
			currentRegistryProcessors.clear();

			// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
			// 下面的代碼就是執(zhí)行沒(méi)有實(shí)現(xiàn)PriorityOrdered接口也沒(méi)有Ordered的BeanDefinitionRegistryPostProcessor
			boolean reiterate = true;
			while (reiterate) {
				reiterate = false;
				postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
				for (String ppName : postProcessorNames) {
					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.
			//registryProcessors集合裝載BeanDefinitionRegistryPostProcessor
			//上面的代碼是執(zhí)行bfr后置處理器子類獨(dú)有的方法，這里需要再把bfr后置處理器父類的方法也執(zhí)行一次
			invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
			//regularPostProcessors裝載BeanFactoryPostProcessor，執(zhí)行BeanFactoryPostProcessor的方法
			//但是regularPostProcessors一般情況下，是不會(huì)有數(shù)據(jù)的，只有在外面手動(dòng)添加BeanFactoryPostProcessor，才會(huì)有數(shù)據(jù)
			invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
		}

		else {
			// Invoke factory processors registered with the context instance.
			// 若bfp沒(méi)有繼承bdrp則直接執(zhí)行手動(dòng)增加bf后置處理器的后置處理器
			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!
		// 找到BeanFactoryPostProcessor實(shí)現(xiàn)類的BeanName數(shù)組
		// 處理Spring自己的bf后置處理器
		String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

		// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		// PriorityOrdered的bf后置處理器集合
		List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		// Ordered的bf后置處理器集合
		List<String> orderedPostProcessorNames = new ArrayList<>();
		// 無(wú)PriorityOrdered無(wú)Ordered的bf后置處理器集合
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		//循環(huán)BeanName數(shù)組
		for (String ppName : postProcessorNames) {
			//如果這個(gè)Bean被執(zhí)行過(guò)了，跳過(guò)
			if (processedBeans.contains(ppName)) {
				// skip - already processed in first phase above
			}
			//如果實(shí)現(xiàn)了PriorityOrdered接口，加入到priorityOrderedPostProcessors
			else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
			}
			//如果實(shí)現(xiàn)了Ordered接口，加入到orderedPostProcessorNames
			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				orderedPostProcessorNames.add(ppName);
			}
			//如果既沒(méi)有實(shí)現(xiàn)PriorityOrdered，也沒(méi)有實(shí)現(xiàn)Ordered。加入到nonOrderedPostProcessorNames
			else {
				nonOrderedPostProcessorNames.add(ppName);
			}
		}

		// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
		//排序處理priorityOrderedPostProcessors，即實(shí)現(xiàn)了PriorityOrdered接口的BeanFactoryPostProcessor
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		//執(zhí)行priorityOrderedPostProcessors
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		//執(zhí)行實(shí)現(xiàn)了Ordered接口的BeanFactoryPostProcessor
		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.
		// 執(zhí)行既沒(méi)有實(shí)現(xiàn)PriorityOrdered接口，也沒(méi)有實(shí)現(xiàn)Ordered接口的BeanFactoryPostProcessor
		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...
		// 清除了allBeanNamesByType&singletonBeanNamesByType()
		// 清除緩存中的bd，因?yàn)楹筇幚砥骺赡苡行薷牧嗽荚獢?shù)據(jù)，例如替換值中的占位符
		beanFactory.clearMetadataCache();
	}