<T> void doRegisterBean(Class<T> annotatedClass, @Nullable Supplier<T> instanceSupplier, @Nullable String name,
		@Nullable Class<? extends Annotation>[] qualifiers, BeanDefinitionCustomizer... definitionCustomizers) {
	// 解析傳入的配置類，實(shí)際上這個(gè)方法既可以解析配置類，也可以解析 Spring bean 對(duì)象
	AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
	// 判斷是否需要跳過，判斷依據(jù)是此類上有沒有 @Conditional 注解
	if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
		return;
	}
	abd.setInstanceSupplier(instanceSupplier);
	ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
	abd.setScope(scopeMetadata.getScopeName());
	String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
	// 處理類上的通用注解
	AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
	if (qualifiers != null) {
		for (Class<? extends Annotation> qualifier : qualifiers) {
			if (Primary.class == qualifier) {
				abd.setPrimary(true);
			}
			else if (Lazy.class == qualifier) {
				abd.setLazyInit(true);
			}
			else {
				abd.addQualifier(new AutowireCandidateQualifier(qualifier));
			}
		}
	}
	// 封裝成一個(gè) BeanDefinitionHolder
	for (BeanDefinitionCustomizer customizer : definitionCustomizers) {
		customizer.customize(abd);
	}
	BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
	// 處理 scopedProxyMode
	definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
	// 把 BeanDefinitionHolder 注冊(cè)到 registry
	BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}

public void refresh() throws BeansException, IllegalStateException {
	synchronized (this.startupShutdownMonitor) {
		// Prepare this context for refreshing.
		// 1. 刷新前的預(yù)處理
		prepareRefresh();
		// Tell the subclass to refresh the internal bean factory.
		// 2. 獲取 beanFactory，即前面創(chuàng)建的【DefaultListableBeanFactory】
		ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
		// Prepare the bean factory for use in this context.
		// 3. 預(yù)處理 beanFactory，向容器中添加一些組件
		prepareBeanFactory(beanFactory);
		try {
			// Allows post-processing of the bean factory in context subclasses.
			// 4. 子類通過重寫這個(gè)方法可以在 BeanFactory 創(chuàng)建并與準(zhǔn)備完成以后做進(jìn)一步的設(shè)置
			postProcessBeanFactory(beanFactory);
			// Invoke factory processors registered as beans in the context.
			// 5. 執(zhí)行 BeanFactoryPostProcessor 方法，beanFactory 后置處理器
			invokeBeanFactoryPostProcessors(beanFactory);
			// Register bean processors that intercept bean creation.
			// 6. 注冊(cè) BeanPostProcessors，bean 后置處理器
			registerBeanPostProcessors(beanFactory);
			// Initialize message source for this context.
			// 7. 初始化 MessageSource 組件（做國(guó)際化功能；消息綁定，消息解析）
			initMessageSource();
			// Initialize event multicaster for this context.
			// 8. 初始化事件派發(fā)器，在注冊(cè)監(jiān)聽器時(shí)會(huì)用到
			initApplicationEventMulticaster();
			// Initialize other special beans in specific context subclasses.
			// 9. 留給子容器（子類），子類重寫這個(gè)方法，在容器刷新的時(shí)候可以自定義邏輯，web 場(chǎng)景下會(huì)使用
			onRefresh();
			// Check for listener beans and register them.
			// 10. 注冊(cè)監(jiān)聽器，派發(fā)之前步驟產(chǎn)生的一些事件（可能沒有）
			registerListeners();
			// Instantiate all remaining (non-lazy-init) singletons.
			// 11. 初始化所有的非單實(shí)例 bean
			finishBeanFactoryInitialization(beanFactory);
			// Last step: publish corresponding event.
			// 12. 發(fā)布容器刷新完成事件
			finishRefresh();
		}
		...
	}
}

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
	// Tell the internal bean factory to use the context's class loader etc.
	// 設(shè)置 classLoader
	beanFactory.setBeanClassLoader(getClassLoader());
	//設(shè)置 bean 表達(dá)式解析器
	beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
	beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
	// Configure the bean factory with context callbacks.
	// 添加一個(gè) BeanPostProcessor【ApplicationContextAwareProcessor】
	beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
	// 設(shè)置忽略自動(dòng)裝配的接口，即不能通過注解自動(dòng)注入
	beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
	beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
	beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
	beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
	beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
	beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
	// BeanFactory interface not registered as resolvable type in a plain factory.
	// MessageSource registered (and found for autowiring) as a bean.
	// 注冊(cè)可以解析的自動(dòng)裝配類，即可以在任意組件中通過注解自動(dòng)注入
	beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
	beanFactory.registerResolvableDependency(ResourceLoader.class, this);
	beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
	beanFactory.registerResolvableDependency(ApplicationContext.class, this);
	// Register early post-processor for detecting inner beans as ApplicationListeners.
	// 添加一個(gè) BeanPostProcessor【ApplicationListenerDetector】
	beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
	// Detect a LoadTimeWeaver and prepare for weaving, if found.
	// 添加編譯時(shí)的 AspectJ
	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()));
	}
	// Register default environment beans.
	// 注冊(cè) environment 組件，類型是【ConfigurableEnvironment】
	if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
		beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
	}
	// 注冊(cè) systemProperties 組件，類型是【Map<String, Object>】
	if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
		beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
	}
	// 注冊(cè) systemEnvironment 組件，類型是【Map<String, Object>】
	if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
		beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
	}
}

public static void invokeBeanFactoryPostProcessors(
		ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
	// beanFactoryPostProcessors 這個(gè)參數(shù)是指用戶通過 AnnotationConfigApplicationContext.addBeanFactoryPostProcessor() 方法手動(dòng)傳入的 BeanFactoryPostProcessor，沒有交給 spring 管理
	// Invoke BeanDefinitionRegistryPostProcessors first, if any.
	// 代表執(zhí)行過的 BeanDefinitionRegistryPostProcessor
	Set<String> processedBeans = new HashSet<>();
	if (beanFactory instanceof BeanDefinitionRegistry) {
		BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
		// 常規(guī)后置處理器集合，即實(shí)現(xiàn)了 BeanFactoryPostProcessor 接口
		List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
		// 注冊(cè)后置處理器集合，即實(shí)現(xiàn)了 BeanDefinitionRegistryPostProcessor 接口
		List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
		// 處理自定義的 beanFactoryPostProcessors（指調(diào)用 context.addBeanFactoryPostProcessor() 方法），一般這里都沒有
		for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
			if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
				BeanDefinitionRegistryPostProcessor registryProcessor =
						(BeanDefinitionRegistryPostProcessor) postProcessor;
				// 調(diào)用 postProcessBeanDefinitionRegistry 方法
				registryProcessor.postProcessBeanDefinitionRegistry(registry);
				registryProcessors.add(registryProcessor);
			}
			else {
				regularPostProcessors.add(postProcessor);
			}
		}
		// Do not initialize 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.
		// 定義一個(gè)變量 currentRegistryProcessors，表示當(dāng)前要處理的 BeanFactoryPostProcessors
		List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
		// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
		// 首先，從容器中查找實(shí)現(xiàn)了 PriorityOrdered 接口的 BeanDefinitionRegistryPostProcessor 類型，這里只會(huì)查找出一個(gè)【ConfigurationClassPostProcessor】
		String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
		for (String ppName : postProcessorNames) {
			// 判斷是否實(shí)現(xiàn)了 PriorityOrdered 接口
			if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				// 添加到 currentRegistryProcessors
				currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
				// 添加到 processedBeans，表示已經(jīng)處理過這個(gè)類了
				processedBeans.add(ppName);
			}
		}
		// 設(shè)置排列順序
		sortPostProcessors(currentRegistryProcessors, beanFactory);
		// 添加到 registry 中
		registryProcessors.addAll(currentRegistryProcessors);
		// 執(zhí)行 [postProcessBeanDefinitionRegistry] 回調(diào)方法
		invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
		// 將 currentRegistryProcessors 變量清空，下面會(huì)繼續(xù)用到
		currentRegistryProcessors.clear();
		// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
		// 接下來，從容器中查找實(shí)現(xiàn)了 Ordered 接口的 BeanDefinitionRegistryPostProcessors 類型，這里可能會(huì)查找出多個(gè)
		// 因?yàn)椤綜onfigurationClassPostProcessor】已經(jīng)完成了 postProcessBeanDefinitionRegistry() 方法，已經(jīng)向容器中完成掃描工作，所以容器會(huì)有很多個(gè)組件
		postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
		for (String ppName : postProcessorNames) {
			// 判斷 processedBeans 是否處理過這個(gè)類，且是否實(shí)現(xiàn) Ordered 接口
			if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
				currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
				processedBeans.add(ppName);
			}
		}
		// 設(shè)置排列順序
		sortPostProcessors(currentRegistryProcessors, beanFactory);
		// 添加到 registry 中
		registryProcessors.addAll(currentRegistryProcessors);
		// 執(zhí)行 [postProcessBeanDefinitionRegistry] 回調(diào)方法
		invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
		// 將 currentRegistryProcessors 變量清空，下面會(huì)繼續(xù)用到
		currentRegistryProcessors.clear();
		// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
		// 最后，從容器中查找剩余所有常規(guī)的 BeanDefinitionRegistryPostProcessors 類型
		boolean reiterate = true;
		while (reiterate) {
			reiterate = false;
			// 根據(jù)類型從容器中查找
			postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				// 判斷 processedBeans 是否處理過這個(gè)類
				if (!processedBeans.contains(ppName)) {
					// 添加到 currentRegistryProcessors
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					// 添加到 processedBeans，表示已經(jīng)處理過這個(gè)類了
					processedBeans.add(ppName);
					// 將標(biāo)識(shí)設(shè)置為 true，繼續(xù)循環(huán)查找，可能隨時(shí)因?yàn)榉乐瓜旅嬲{(diào)用了 invokeBeanDefinitionRegistryPostProcessors() 方法引入新的后置處理器
					reiterate = true;
				}
			}
			// 設(shè)置排列順序
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			// 添加到 registry 中
			registryProcessors.addAll(currentRegistryProcessors);
			// 執(zhí)行 [postProcessBeanDefinitionRegistry] 回調(diào)方法
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			// 將 currentRegistryProcessors 變量清空，因?yàn)橄乱淮窝h(huán)可能會(huì)用到
			currentRegistryProcessors.clear();
		}
		// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
		// 現(xiàn)在執(zhí)行 registryProcessors 的 [postProcessBeanFactory] 回調(diào)方法
		invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
		// 執(zhí)行 regularPostProcessors 的 [postProcessBeanFactory] 回調(diào)方法，也包含用戶手動(dòng)調(diào)用 addBeanFactoryPostProcessor() 方法添加的 BeanFactoryPostProcessor
		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!
	// 從容器中查找實(shí)現(xiàn)了 BeanFactoryPostProcessor 接口的類
	String[] postProcessorNames =
			beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
	// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
	// Ordered, and the rest.
	// 表示實(shí)現(xiàn)了 PriorityOrdered 接口的 BeanFactoryPostProcessor
	List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
	// 表示實(shí)現(xiàn)了 Ordered 接口的 BeanFactoryPostProcessor
	List<String> orderedPostProcessorNames = new ArrayList<>();
	// 表示剩下來的常規(guī)的 BeanFactoryPostProcessors
	List<String> nonOrderedPostProcessorNames = new ArrayList<>();
	for (String ppName : postProcessorNames) {
		// 判斷是否已經(jīng)處理過，因?yàn)?postProcessorNames 其實(shí)包含了上面步驟處理過的 BeanDefinitionRegistry 類型
		if (processedBeans.contains(ppName)) {
			// skip - already processed in first phase above
		}
		// 判斷是否實(shí)現(xiàn)了 PriorityOrdered 接口
		else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
			priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
		}
		// 判斷是否實(shí)現(xiàn)了 Ordered 接口
		else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
			orderedPostProcessorNames.add(ppName);
		}
		// 剩下所有常規(guī)的
		else {
			nonOrderedPostProcessorNames.add(ppName);
		}
	}
	// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
	// 先將 priorityOrderedPostProcessors 集合排序
	sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
	// 執(zhí)行 priorityOrderedPostProcessors 的 [postProcessBeanFactory] 回調(diào)方法
	invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
	// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
	// 接下來，把 orderedPostProcessorNames 轉(zhuǎn)成 orderedPostProcessors 集合
	List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
	for (String postProcessorName : orderedPostProcessorNames) {
		orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
	}
	// 將 orderedPostProcessors 集合排序
	sortPostProcessors(orderedPostProcessors, beanFactory);
	// 執(zhí)行 orderedPostProcessors 的 [postProcessBeanFactory] 回調(diào)方法
	invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
	// Finally, invoke all other BeanFactoryPostProcessors.
	// 最后把 nonOrderedPostProcessorNames 轉(zhuǎn)成 nonOrderedPostProcessors 集合，這里只有一個(gè)，myBeanFactoryPostProcessor
	List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
	for (String postProcessorName : nonOrderedPostProcessorNames) {
		nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
	}
	// 執(zhí)行 nonOrderedPostProcessors 的 [postProcessBeanFactory] 回調(diào)方法
	invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
	// Clear cached merged bean definitions since the post-processors might have
	// modified the original metadata, e.g. replacing placeholders in values...
	// 清除緩存
	beanFactory.clearMetadataCache();
}

public static void registerBeanPostProcessors(
		ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
	// 從容器中獲取 BeanPostProcessor 類型
	String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
	// Register BeanPostProcessorChecker that logs an info message when
	// a bean is created during BeanPostProcessor instantiation, i.e. when
	// a bean is not eligible for getting processed by all BeanPostProcessors.
	int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
	// 向容器中添加【BeanPostProcessorChecker】，主要是用來檢查是不是有 bean 已經(jīng)初始化完成了，
	// 如果沒有執(zhí)行所有的 beanPostProcessor（用數(shù)量來判斷），如果有就會(huì)打印一行 info 日志
	beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
	// Separate between BeanPostProcessors that implement PriorityOrdered,
	// Ordered, and the rest.
	// 存放實(shí)現(xiàn)了 PriorityOrdered 接口的 BeanPostProcessor
	List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
	// 存放 MergedBeanDefinitionPostProcessor 類型的 BeanPostProcessor
	List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
	// 存放實(shí)現(xiàn)了 Ordered 接口的 BeanPostProcessor 的 name
	List<String> orderedPostProcessorNames = new ArrayList<>();
	// 存放剩下來普通的 BeanPostProcessor 的 name
	List<String> nonOrderedPostProcessorNames = new ArrayList<>();
	// 從 beanFactory 中查找 postProcessorNames 里的 bean，然后放到對(duì)應(yīng)的集合中
	for (String ppName : postProcessorNames) {
		// 判斷有無實(shí)現(xiàn) PriorityOrdered 接口
		if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
			priorityOrderedPostProcessors.add(pp);
			// 如果實(shí)現(xiàn)了 PriorityOrdered 接口，且屬于 MergedBeanDefinitionPostProcessor
			if (pp instanceof MergedBeanDefinitionPostProcessor) {
				// 把 MergedBeanDefinitionPostProcessor 類型的添加到 internalPostProcessors 集合中
				internalPostProcessors.add(pp);
			}
		}
		else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
			orderedPostProcessorNames.add(ppName);
		}
		else {
			nonOrderedPostProcessorNames.add(ppName);
		}
	}
	// First, register the BeanPostProcessors that implement PriorityOrdered.
	// 給 priorityOrderedPostProcessors 排序
	sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
	// 先注冊(cè)實(shí)現(xiàn)了 PriorityOrdered 接口的 beanPostProcessor
	registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
	// Next, register the BeanPostProcessors that implement Ordered.
	// 從 beanFactory 中查找 orderedPostProcessorNames 里的 bean，然后放到對(duì)應(yīng)的集合中
	List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
	for (String ppName : orderedPostProcessorNames) {
		BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
		orderedPostProcessors.add(pp);
		if (pp instanceof MergedBeanDefinitionPostProcessor) {
			internalPostProcessors.add(pp);
		}
	}
	// 給 orderedPostProcessors 排序
	sortPostProcessors(orderedPostProcessors, beanFactory);
	// 再注冊(cè)實(shí)現(xiàn)了 Ordered 接口的 beanPostProcessor
	registerBeanPostProcessors(beanFactory, orderedPostProcessors);
	// Now, register all regular BeanPostProcessors.
	List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
	for (String ppName : nonOrderedPostProcessorNames) {
		BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
		nonOrderedPostProcessors.add(pp);
		if (pp instanceof MergedBeanDefinitionPostProcessor) {
			internalPostProcessors.add(pp);
		}
	}
	// 再注冊(cè)常規(guī)的 beanPostProcessor
	registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
	// Finally, re-register all internal BeanPostProcessors.
	// 排序 MergedBeanDefinitionPostProcessor 這種類型的 beanPostProcessor
	sortPostProcessors(internalPostProcessors, beanFactory);
	// 最后注冊(cè) MergedBeanDefinitionPostProcessor 類型的 beanPostProcessor
	registerBeanPostProcessors(beanFactory, internalPostProcessors);
	// Re-register post-processor for detecting inner beans as ApplicationListeners,
	// moving it to the end of the processor chain (for picking up proxies etc).
	// 給容器中添加【ApplicationListenerDetector】 beanPostProcessor，判斷是不是監(jiān)聽器，如果是就把 bean 放到容器中保存起來
	// 此時(shí)容器中默認(rèn)會(huì)有 6 個(gè)內(nèi)置的 beanPostProcessor
		// 0 = {ApplicationContextAwareProcessor@1632}
		//	1 = {ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor@1633}
		//	2 = {PostProcessorRegistrationDelegate$BeanPostProcessorChecker@1634}
		//	3 = {CommonAnnotationBeanPostProcessor@1635}
		//	4 = {AutowiredAnnotationBeanPostProcessor@1636}
		//	5 = {ApplicationListenerDetector@1637}
	beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}

protected void initApplicationEventMulticaster() {
	// 獲取 beanFactory
	ConfigurableListableBeanFactory beanFactory = getBeanFactory();
	// 看看容器中是否有自定義的 applicationEventMulticaster
	if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
		// 有就從容器中獲取賦值
		this.applicationEventMulticaster =
				beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
		if (logger.isTraceEnabled()) {
			logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
		}
	}
	else {
		// 沒有，就創(chuàng)建一個(gè) SimpleApplicationEventMulticaster
		this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
		// 將創(chuàng)建的 ApplicationEventMulticaster 添加到 BeanFactory 中， 其他組件就可以自動(dòng)注入了
		beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
		if (logger.isTraceEnabled()) {
			logger.trace("No '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "' bean, using " +
					"[" + this.applicationEventMulticaster.getClass().getSimpleName() + "]");
		}
	}
}

protected void registerListeners() {
	// Register statically specified listeners first.
	// 獲取之前步驟中保存的 ApplicationListener
	for (ApplicationListener<?> listener : getApplicationListeners()) {
		// getApplicationEventMulticaster() 就是獲取之前步驟初始化的 applicationEventMulticaster
		getApplicationEventMulticaster().addApplicationListener(listener);
	}
	// Do not initialize FactoryBeans here: We need to leave all regular beans
	// uninitialized to let post-processors apply to them!
	// 從容器中獲取所有的 ApplicationListener
	String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
	for (String listenerBeanName : listenerBeanNames) {
		getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
	}
	// Publish early application events now that we finally have a multicaster...
	// 派發(fā)之前步驟產(chǎn)生的 application events
	Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
	this.earlyApplicationEvents = null;
	if (earlyEventsToProcess != null) {
		for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
			getApplicationEventMulticaster().multicastEvent(earlyEvent);
		}
	}
}

public void preInstantiateSingletons() throws BeansException {
	if (logger.isTraceEnabled()) {
		logger.trace("Pre-instantiating singletons in " + this);
	}
	// Iterate over a copy to allow for init methods which in turn register new bean definitions.
	// While this may not be part of the regular factory bootstrap, it does otherwise work fine.
	// 獲取容器中的所有 beanDefinitionName
	List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);
	// Trigger initialization of all non-lazy singleton beans...
	// 循環(huán)進(jìn)行初始化和創(chuàng)建對(duì)象
	for (String beanName : beanNames) {
		// 獲取 RootBeanDefinition，它表示自己的 BeanDefinition 和可能存在父類的 BeanDefinition 合并后的對(duì)象
		RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
		// 如果是非抽象的，且單實(shí)例，非懶加載
		if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
			// 如果是 factoryBean，利用下面這種方法創(chuàng)建對(duì)象
			if (isFactoryBean(beanName)) {
				// 如果是 factoryBean，則 加上 &，先創(chuàng)建工廠 bean
				Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
				if (bean instanceof FactoryBean) {
					final FactoryBean<?> factory = (FactoryBean<?>) bean;
					boolean isEagerInit;
					if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
						isEagerInit = AccessController.doPrivileged((PrivilegedAction<Boolean>)
										((SmartFactoryBean<?>) factory)::isEagerInit,
								getAccessControlContext());
					}
					else {
						isEagerInit = (factory instanceof SmartFactoryBean &&
								((SmartFactoryBean<?>) factory).isEagerInit());
					}
					if (isEagerInit) {
						getBean(beanName);
					}
				}
			}
			else {
				// 不是工廠 bean，用這種方法創(chuàng)建對(duì)象
				getBean(beanName);
			}
		}
	}
	// Trigger post-initialization callback for all applicable beans...
	for (String beanName : beanNames) {
		Object singletonInstance = getSingleton(beanName);
		// 檢查所有的 bean 是否是 SmartInitializingSingleton 接口
		if (singletonInstance instanceof SmartInitializingSingleton) {
			final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
			if (System.getSecurityManager() != null) {
				AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
					smartSingleton.afterSingletonsInstantiated();
					return null;
				}, getAccessControlContext());
			}
			else {
				// 回調(diào) afterSingletonsInstantiated() 方法，可以在回調(diào)中做一些事情
				smartSingleton.afterSingletonsInstantiated();
			}
		}
	}
}

protected void finishRefresh() {
	// Clear context-level resource caches (such as ASM metadata from scanning).
	// 清理緩存
	clearResourceCaches();
	// Initialize lifecycle processor for this context.
	// 初始化和生命周期有關(guān)的后置處理器
	initLifecycleProcessor();
	// Propagate refresh to lifecycle processor first.
	// 拿到前面定義的生命周期處理器【LifecycleProcessor】回調(diào) onRefresh() 方法
	getLifecycleProcessor().onRefresh();
	// Publish the final event.
	// 發(fā)布容器刷新完成事件
	publishEvent(new ContextRefreshedEvent(this));
	// Participate in LiveBeansView MBean, if active.
	LiveBeansView.registerApplicationContext(this);
}