【四】Spring源码分析之启动主流程---AbstractApplicationContext的refresh方法

入口：

在SpringBoot启动的时候，SpringApplication的run方法中

refreshContext(context);

 里面最终调用的是AbstractApplicationContext类的refresh方法来刷新容器

源码：

@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {

            // 设置Spring容器的启动时间，撤销关闭状态，开启活跃状态
			prepareRefresh();

            // 得到BeanFactory
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

            // 给BeanFactory设置一些属性
			prepareBeanFactory(beanFactory);

			try {

                // 后置处理BeanFactory
				postProcessBeanFactory(beanFactory);

                // 注册并调用BeanFactoryPostProcessor后置处理器
                // 其中ConfigurationClassPostProcessor这个后置处理器会扫描Bean并且注册到容器中
				invokeBeanFactoryPostProcessors(beanFactory);

                // 注册BeanPostProcessor后置处理器，这里的后置处理器在下方实例化Bean方法中会用到
				registerBeanPostProcessors(beanFactory);

				initMessageSource();

                // 初始化ApplicationEventMulticaster
				initApplicationEventMulticaster();

                //创建tomcat启动了Tomcat的Server、Service、Container、Engine、Realm、Pipeline、Value、MapperListerner
                onRefresh();

                // 注册监听器
				registerListeners();

                // 实例化非懒加载的Bean
				finishBeanFactoryInitialization(beanFactory);

                // 启动tomcat的Connector
				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.
				destroyBeans();

				// Reset 'active' flag.
				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();
			}
		}
	}

方法详解

1.prepareRefresh方法

源码

调用AnnotationConfigEmbeddedWebApplicationContext类的prepareRefresh

	@Override
	protected void prepareRefresh() {
		this.scanner.clearCache();
		super.prepareRefresh();
	}

这里super会调用AbstractApplicationContext的PrepareRefresh方法

	protected void prepareRefresh() {
		this.startupDate = System.currentTimeMillis();
		this.closed.set(false);
		this.active.set(true);

		if (logger.isInfoEnabled()) {
			logger.info("Refreshing " + this);
		}

		// Initialize any placeholder property sources in the context environment
		initPropertySources();

		// Validate that all properties marked as required are resolvable
		// see ConfigurablePropertyResolver#setRequiredProperties
		getEnvironment().validateRequiredProperties();

		// Allow for the collection of early ApplicationEvents,
		// to be published once the multicaster is available...
		this.earlyApplicationEvents = new LinkedHashSet();
	}

控制台打印的这句话就在这里

2019-02-22 15:50:01.994  INFO 1560 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@6c7a164b: startup date [Fri Feb 22 15:49:59 CST 2019]; root of context hierarchy

 做了4件事

1.清除源数据缓存

2.设置Spring容器的启动时间，撤销关闭状态，开启活跃状态。

3.初始化属性源信息，调用的是WebApplicationContextUtils类的initServletPropertySources方法。这里因为servletContext和servletConfig为空，所以什么都没做。

4.验证环境信息里一些必须存在的属性。调用的AbstractPropertyResolver类的validateRequiredProperties方法。这里因为this.requiredProperties里面没有元素，所以什么都没做。

 2.obtainFreshBeanFactory方法

源码

	protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
		refreshBeanFactory();
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		if (logger.isDebugEnabled()) {
			logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
		}
		return beanFactory;
	}

调用子类refreshBeanFactory方法

	@Override
	protected final void refreshBeanFactory() throws IllegalStateException {
		if (!this.refreshed.compareAndSet(false, true)) {
			throw new IllegalStateException(
					"GenericApplicationContext does not support multiple refresh attempts: just call 'refresh' once");
		}
		this.beanFactory.setSerializationId(getId());
	}

 做了2件事

1.调用子类的refeshBeanFactory(),设置BeanFactory的SerializationId,把SerializationId和弱引用的DefaultListableBeanFacotry注册到beanFactory的serializableFactories属性（一个Map）中，设置refreshed标志为true。

2.获取BeanFactory，这里是org.springframework.beans.factory.support.DefaultListableBeanFactory类，在创建applicationContext的时候就创建了它。

3.如果XmlWebApplicationContext ，AnnotationConfigApplicationContext类容器， 会在这一步加载BeanFactory。

而我们这里debug的是AnnotationConfigEmbeddedWebApplicationContext容器，在容器创建的时候就创建好了BeanFactory。

3.prepareBeanFactory方法

源码

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// Tell the internal bean factory to use the context's class loader etc.
		beanFactory.setBeanClassLoader(getClassLoader());
		beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// Configure the bean factory with context callbacks.
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
		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.
		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.
		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));

		// Detect a LoadTimeWeaver and prepare for weaving, if found.
		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.
		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());
		}
	}

做了5件事

1.给BeanFactory设置BeanClassLoader类加载器，设置BeanExpressionResolver表达式解析器，设置PropertyEditorRegistrar资源编辑注册器。

2.给BeanFactory添加BeanPostProcessor。这里是加的ApplicationContextAwareProcessor。

在ignoredDependencyInterfaces集合中加入EnvironmentAware、EmbeddedValueResolverAware、ResourceLoaderAware、ApplicationEventPublisherAware、MessageSourceAware、ApplicationContextAware、

3.给BeanFactory注册解析依赖。往resolvableDependencies(是Map)注册BeanFactory、ResourceLoader、ApplicationEventPublisher、ApplicationContext

4.给BeanFactory添加BeanPostProcessor。这里是加的ApplicationListenerDetector。

5.给BeanFactory注册一些单例Bean,如：environment、systemProperties、systemEnvironment

4.postProcessBeanFactory方法

源码

 AnnotationConfigEmbeddedWebApplicationContext类

	@Override
	protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
        // 调用父类EmbeddedWebApplicationContext的实现
		super.postProcessBeanFactory(beanFactory);

        // 查看basePackages属性，如果设置了会使用ClassPathBeanDefinitionScanner去扫描basePackages包下的bean并注册
		if (this.basePackages != null && this.basePackages.length > 0) {
			this.scanner.scan(this.basePackages);
		}

        // 查看annotatedClasses属性，如果设置了会使用AnnotatedBeanDefinitionReader去注册这些bean
		if (this.annotatedClasses != null && this.annotatedClasses.length > 0) {
			this.reader.register(this.annotatedClasses);
		}
	}

父类EmbeddedWebApplicationContext

	@Override
	protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		beanFactory.addBeanPostProcessor(
				new WebApplicationContextServletContextAwareProcessor(this));
		beanFactory.ignoreDependencyInterface(ServletContextAware.class);
	}

 做了2件事

1.给beanFactory添加BeanPostProcessor后置处理器WebApplicationContextServletContextAwareProcessor

2.给beanFactory添加ignoredDependencyInterfaces忽略依赖接口ServletContextAware

5. invokeBeanFactoryPostProcessors方法

源码

	protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
		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()));
		}
	}

委托给PostProcessorRegistrationDelegate的invokeBeanFactoryPostProcessors方法执行。这个方法写得很恶心，真的，一点都不优雅！

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

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

		if (beanFactory instanceof BeanDefinitionRegistry) {
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
			List regularPostProcessors = new LinkedList();
			List registryProcessors = new LinkedList();

            将ApplicationContext中的后置处理器BeanFactoryPostProcessors分类为常规的后置处理器（PropertySourceOrderingPostProcessor）和注册BeanDefinition的后置处理器（ConfigurationWarningsPostProcessor、CachingMetadataReaderFactoryPostProcessor）

			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;

 执行ApplicationContext中注册BeanDefinition的后置处理器（ConfigurationWarningsPostProcessor、CachingMetadataReaderFactoryPostProcessor）的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.
			List currentRegistryProcessors = new ArrayList();

			// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
			String[] postProcessorNames =
					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {

把BeanFactory中已经进注册表了的BeanDefinition信息的注册BeanDefinition的后置处理器BeanFactoryPostProcessors实例化。这里即是ConfigurationClassPostProcessor类

					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			registryProcessors.addAll(currentRegistryProcessors);

           
调用了ConfigurationClassPostProcessor类的postProcessBeanDefinitionRegistry方法，把扫描到的所有BeanDefinition都注册到容器的注册表（一个Map）中

			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			currentRegistryProcessors.clear();

			// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
			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);
				}
			}
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			registryProcessors.addAll(currentRegistryProcessors);
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			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) {
					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.

调用所有注册BeanDefinition的后置处理器的postProcessBeanFactory

			invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);

调用所有常规后置处理器的postProcessBeanFactory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!
		String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

		// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.

    把BeanFactory中已经进注册表了的BeanDefinition信息的所有BeanFactoryPostProcessors后置处理器实例化，按照priorityOrdered、Ordered、nonOrdered分类。

		List priorityOrderedPostProcessors = new ArrayList();
		List orderedPostProcessorNames = new ArrayList();
		List nonOrderedPostProcessorNames = new ArrayList();
		for (String ppName : postProcessorNames) {
			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.

调用priorityOrdered分类中所有后置处理器（PropertySourcesPlaceholderConfigurer）的postProcessBeanFactory方法。

		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.

调用Ordered分类中所有后置处理器的postProcessBeanFactory方法。其实这里，这个分类是空的。

		List 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.


调用nonOrdered分类中所有后置处理器（ConfigurationBeanFactoryMetaData、ErrorMvcAutoConfiguration.PreserveErrorControllerTargetClassPostProcessor）的postProcessBeanFactory方法。

		List 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();
	}

 该方法分为两大部分：

第一部分做了5件事：

1.将ApplicationContext中的后置处理器BeanFactoryPostProcessors分类为常规的后置处理器（PropertySourceOrderingPostProcessor）和注册BeanDefinition的后置处理器（ConfigurationWarningsPostProcessor、CachingMetadataReaderFactoryPostProcessor）

2.执行ApplicationContext中注册BeanDefinition的后置处理器（ConfigurationWarningsPostProcessor、CachingMetadataReaderFactoryPostProcessor）的postProcessBeanDefinitionRegistry方法。

3.把BeanFactory中已经进注册表了的BeanDefinition信息的注册BeanDefinition的后置处理器BeanFactoryPostProcessors实例化。这里即是ConfigurationClassPostProcessor类。调用了ConfigurationClassPostProcessor类的postProcessBeanDefinitionRegistry方法，把BeanDefinition都注册到容器的注册表（一个Map）中，先注册PriorityOrdered，再注册Ordered，再注册nonOrdered的

4.调用所有注册BeanDefinition的后置处理器的postProcessBeanFactory

其中调用了ConfigurationClassPostProcessor的postProcessBeanFactory方法。其他两个注册BeanDefinition后置处理器的该方法是空的。

该方法中调用enhanceConfigurationClasses用来将标记@Configuration的配置类的BeanDefinition的beanClass替换为经过cglib加强过的，这样在实例化此bean的时候，就可以使用替换的代理类来创建对象了。此处跟AOP有关。

该在BeanFactory中添加一个后置处理器ImportAwareBeanPostProcessor。

5.调用所有常规后置处理器的postProcessBeanFactory方法。

即是PropertySourceOrderingPostProcessor的postProcessBeanFactory方法。

这里专门另外写一篇来介绍 ConfigurationClassPostProcessor类postProcessBeanDefinitionRegistry方法是怎么把所有的bean扫到注册到IOC的注册表总的：

【八】Spring Boot 源码分析之启动主流程----ConfigurationClassPostProcessor的processConfigBeanDefinitionRegistry方法

第二部分做了5件事：

1.把BeanFactory中已经进注册表了的BeanDefinition信息的所有BeanFactoryPostProcessors后置处理器实例化，按照priorityOrdered、Ordered、nonOrdered分类。

2.调用priorityOrdered分类中所有后置处理器（PropertySourcesPlaceholderConfigurer）的postProcessBeanFactory方法。

3.调用Ordered分类中所有后置处理器的postProcessBeanFactory方法。其实这里，这个分类是空的。

4.调用nonOrdered分类中所有后置处理器（ConfigurationBeanFactoryMetaData、ErrorMvcAutoConfiguration.PreserveErrorControllerTargetClassPostProcessor）的postProcessBeanFactory方法。

5.清空beanFactory源数据缓存

6.registerBeanPostProcessors方法

源码

	protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
		PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
	}

 委托给PostProcessorRegistrationDelegate的静态方法registerBeanPostProcessors执行。这个方法写得很恶心，真的，一点都不优雅！

public static void registerBeanPostProcessors(
			ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {

		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;
		beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

		// Separate between BeanPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		List priorityOrderedPostProcessors = new ArrayList();
		List internalPostProcessors = new ArrayList();
		List orderedPostProcessorNames = new ArrayList();
		List nonOrderedPostProcessorNames = new ArrayList();
		for (String ppName : postProcessorNames) {
			if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
				priorityOrderedPostProcessors.add(pp);
				if (pp instanceof MergedBeanDefinitionPostProcessor) {
					internalPostProcessors.add(pp);
				}
			}
			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				orderedPostProcessorNames.add(ppName);
			}
			else {
				nonOrderedPostProcessorNames.add(ppName);
			}
		}

		// First, register the BeanPostProcessors that implement PriorityOrdered.
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

		// Next, register the BeanPostProcessors that implement Ordered.
		List orderedPostProcessors = new ArrayList();
		for (String ppName : orderedPostProcessorNames) {
			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
			orderedPostProcessors.add(pp);
			if (pp instanceof MergedBeanDefinitionPostProcessor) {
				internalPostProcessors.add(pp);
			}
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		registerBeanPostProcessors(beanFactory, orderedPostProcessors);

		// Now, register all regular BeanPostProcessors.
		List nonOrderedPostProcessors = new ArrayList();
		for (String ppName : nonOrderedPostProcessorNames) {
			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
			nonOrderedPostProcessors.add(pp);
			if (pp instanceof MergedBeanDefinitionPostProcessor) {
				internalPostProcessors.add(pp);
			}
		}
		registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);

		// Finally, re-register all internal BeanPostProcessors.
		sortPostProcessors(internalPostProcessors, beanFactory);
		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).
		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
	}

注意这里的BeanPostProcessor，跟上一个方法中的BeanFactoryPostProcessor，不一样！

做了3件事：

1.把BeanFactory中已经进注册表了的BeanDefinition信息的BeanPostProcessor后置处理器实例化。

2.把BeanPostProcessor按照priorityOrdered、ordered、nonOrdered、internalPostProcessors分类。

priorityOrdered：AutowiredAnnotationBeanPostProcessor、RequiredAnnotationBeanPostProcessor、CommonAnnotationBeanPostProcessor、ConfigurationPropertiesBindingPostProcessor

ordered：MethodValidationPostProcessor、AnnotationAwareAspectJAutoProxyCreator（这个跟AOP有关）

nonOrdered：EmbeddedServletContainerCustomizerBeanPostProcessor、ErrorPageRegistrarBeanPostProcessor

internalPostProcessors：AutowiredAnnotationBeanPostProcessor、RequiredAnnotationBeanPostProcessor、CommonAnnotationBeanPostProcessor

3.把各个分类的BeanFactoryPostProcessor后置处理器注册到BeanFactory中

7.initMessageSource方法

初始化上下文中的资源文件，如国际化文件的处理等。这里走的是else。

源码：

protected void initMessageSource() {
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
			this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
			// Make MessageSource aware of parent MessageSource.
			if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
				HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
				if (hms.getParentMessageSource() == null) {
					// Only set parent context as parent MessageSource if no parent MessageSource
					// registered already.
					hms.setParentMessageSource(getInternalParentMessageSource());
				}
			}
			if (logger.isDebugEnabled()) {
				logger.debug("Using MessageSource [" + this.messageSource + "]");
			}
		}
		else {
			// Use empty MessageSource to be able to accept getMessage calls.
			DelegatingMessageSource dms = new DelegatingMessageSource();
			dms.setParentMessageSource(getInternalParentMessageSource());
			this.messageSource = dms;
			beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
			if (logger.isDebugEnabled()) {
				logger.debug("Unable to locate MessageSource with name '" + MESSAGE_SOURCE_BEAN_NAME +
						"': using default [" + this.messageSource + "]");
			}
		}
	}

8.initApplicationEventMulticaster方法

初始化ApplicationEventMulticaster。如果ApplicationContext容器中没有定义ApplicationEventMulticaster，则new一个SimpleApplicationEventMulticaster。这里走的是else。

protected void initApplicationEventMulticaster() {
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
			this.applicationEventMulticaster =
					beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
			if (logger.isDebugEnabled()) {
				logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
			}
		}
		else {
            //我调式的时候是走的这个
			this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
			beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
			if (logger.isDebugEnabled()) {
				logger.debug("Unable to locate ApplicationEventMulticaster with name '" +
						APPLICATION_EVENT_MULTICASTER_BEAN_NAME +
						"': using default [" + this.applicationEventMulticaster + "]");
			}
		}
	}

9.onRefresh方法

源码：调用的EmbeddedWebApplicationContext类的onRefresh方法。

	protected void onRefresh() {
		super.onRefresh();
		try {
			createEmbeddedServletContainer();
		}
		catch (Throwable ex) {
			throw new ApplicationContextException("Unable to start embedded container",
					ex);
		}
	}

重点在createEmbeddedServletContainer方法 

private void createEmbeddedServletContainer() {
		EmbeddedServletContainer localContainer = this.embeddedServletContainer;
		ServletContext localServletContext = getServletContext();
		if (localContainer == null && localServletContext == null) {
			EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory();
			this.embeddedServletContainer = containerFactory
					.getEmbeddedServletContainer(getSelfInitializer());
		}
		else if (localServletContext != null) {
			try {
				getSelfInitializer().onStartup(localServletContext);
			}
			catch (ServletException ex) {
				throw new ApplicationContextException("Cannot initialize servlet context",
						ex);
			}
		}
		initPropertySources();
	}

该方法中会去创建内嵌的Servlet容器，这里既是Tomcat。

跟到里面会发现启动了Tomcat的Server、Service、Container、Engine、Realm、Pipeline、Value、MapperListerner

这里单独写一篇介绍Spring Boot启动的时候走到这个方法后，是怎么去启动内置的Tomcat的

【六】Spring Boot 源码分析之启动内置Tomcat（Tomcat组件、生命周期简介、一次请求）

 10.registerListeners方法

源码：

protected void registerListeners() {
		// Register statically specified listeners first.
		for (ApplicationListener listener : getApplicationListeners()) {
			getApplicationEventMulticaster().addApplicationListener(listener);
		}

		// Do not initialize FactoryBeans here: We need to leave all regular beans
		// uninitialized to let post-processors apply to them!
		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...
		Set earlyEventsToProcess = this.earlyApplicationEvents;
		this.earlyApplicationEvents = null;
		if (earlyEventsToProcess != null) {
			for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
				getApplicationEventMulticaster().multicastEvent(earlyEvent);
			}
		}
	}

做了3件事：

1.把Spring容器内的事件监听器（applicationContext.applicationListener中）注册到事件广播器SimpleApplicationEventMulticaster中

2.把BeanFactory中BeanDefition注册表中有的事件监听器（CachingMetadataReaderFactory、ConfigurationPropertiesBindingPostProcessor、mvcResourceUrlProvider、springApplicationAdminRegistrar、这些是bean的名字，并没有实例化）注册到事件广播器SimpleApplicationEventMulticaster中

3.广播较早的事件，这里是空的，所以并没有广播什么。

11.finishBeanFactoryInitialization方法

源码：

protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
		// Initialize conversion service for this context.
        // 这里未满足条件，直接跳过
		if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
				beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
			beanFactory.setConversionService(
					beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
		}

		// Register a default embedded value resolver if no bean post-processor
		// (such as a PropertyPlaceholderConfigurer bean) registered any before:
		// at this point, primarily for resolution in annotation attribute values.
        // 这里未满足条件，直接跳过
		if (!beanFactory.hasEmbeddedValueResolver()) {
			beanFactory.addEmbeddedValueResolver(new StringValueResolver() {
				@Override
				public String resolveStringValue(String strVal) {
					return getEnvironment().resolvePlaceholders(strVal);
				}
			});
		}

		// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
        // 这里得到的数组是控制，直接跳过
		String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
		for (String weaverAwareName : weaverAwareNames) {
			getBean(weaverAwareName);
		}

		// Stop using the temporary ClassLoader for type matching.
		beanFactory.setTempClassLoader(null);

		// Allow for caching all bean definition metadata, not expecting further changes.
		beanFactory.freezeConfiguration();

		// Instantiate all remaining (non-lazy-init) singletons.
        // 重点在这句话！这句话做bean的初始化工作
		beanFactory.preInstantiateSingletons();
	}

实例化BeanFactory中已经被注册但是未实例化的所有Bean(懒加载的不需要实例化)。即生成环境所需要的Bean。

前面几个if在debug的时候没进去，for循环weaverAwareNames为空也没进去，重点介绍beanFactory.preInstantiateSingletions方法

【五】Spring Boot 源码分析之启动主流程----DefaultListableBeanFactory的preInstantiateSingletons方法

12.finishRefresh方法

源码：

调用子类EmbeddedWebApplicationContext类的finishRefresh方法

protected void finishRefresh() {

        // 调用父类AbstractApplicationContext的finishRefresh 方法
		super.finishRefresh();

        // 启动tomcat的Connector
		EmbeddedServletContainer localContainer = startEmbeddedServletContainer();
		if (localContainer != null) {

        // 用SimpleApplicationEventMulticaster发布EmbeddedServletContainerInitializedEvent事件
			publishEvent(
					new EmbeddedServletContainerInitializedEvent(this, localContainer));
		}
	}

做了3件事：

12.1.调用父类AbstractApplicationContext的finishRefresh 方法

	protected void finishRefresh() {
		// Initialize lifecycle processor for this context.
		initLifecycleProcessor();

        // 初始化生命周期处理器DefaultLifecycleProcessor，调用DefaultLifecycleProcessor含有startBeans方法
		getLifecycleProcessor().onRefresh();

        // 用SimpleApplicationEventMulticaster发布ContextRefreshedEvent事件
		publishEvent(new ContextRefreshedEvent(this));

		LiveBeansView.registerApplicationContext(this);
	}

做了3件事： 

12.1.1.初始化生命周期处理器DefaultLifecycleProcessor，调用DefaultLifecycleProcessor含有startBeans方法

12.1.2.用SimpleApplicationEventMulticaster发布ContextRefreshedEvent事件。

12.1.3.给LiveBeansView注册ApplicationContext

12.1.2 广播出 ContextRefreshedEvent事件后各个监听器执行的逻辑：

12.1.2.1 ConfigurationPropertiesBindingPostProcessor

源码：

public void onApplicationEvent(ContextRefreshedEvent event) {
		freeLocalValidator();
	}

	private void freeLocalValidator() {
		try {
			Validator validator = this.localValidator;
			this.localValidator = null;
			if (validator != null) {
				((DisposableBean) validator).destroy();
			}
		}
		catch (Exception ex) {
			throw new IllegalStateException(ex);
		}
	}

12.1.2.2 DelegatingApplicationListener

源码：并没有监听这个事件

public void onApplicationEvent(ApplicationEvent event) {
		if (event instanceof ApplicationEnvironmentPreparedEvent) {
			List> delegates = getListeners(
					((ApplicationEnvironmentPreparedEvent) event).getEnvironment());
			if (delegates.isEmpty()) {
				return;
			}
			this.multicaster = new SimpleApplicationEventMulticaster();
			for (ApplicationListener listener : delegates) {
				this.multicaster.addApplicationListener(listener);
			}
		}
		if (this.multicaster != null) {
			this.multicaster.multicastEvent(event);
		}
	}

 12.1.2.3 AutoConfigurationReportLoggingInitializer

源码：

	protected void onApplicationEvent(ApplicationEvent event) {
		ConfigurableApplicationContext initializerApplicationContext = AutoConfigurationReportLoggingInitializer.this.applicationContext;
		if (event instanceof ContextRefreshedEvent) {
			if (((ApplicationContextEvent) event)
					.getApplicationContext() == initializerApplicationContext) {
				logAutoConfigurationReport();
			}
		}
		else if (event instanceof ApplicationFailedEvent) {
			if (((ApplicationFailedEvent) event)
					.getApplicationContext() == initializerApplicationContext) {
				logAutoConfigurationReport(true);
			}
		}
	}

调用了logAutoConfigurationReport方法

public void logAutoConfigurationReport(boolean isCrashReport) {
		if (this.report == null) {
			if (this.applicationContext == null) {
				this.logger.info("Unable to provide auto-configuration report "
						+ "due to missing ApplicationContext");
				return;
			}
			this.report = ConditionEvaluationReport
					.get(this.applicationContext.getBeanFactory());
		}
		if (!this.report.getConditionAndOutcomesBySource().isEmpty()) {
			if (isCrashReport && this.logger.isInfoEnabled()
					&& !this.logger.isDebugEnabled()) {
				this.logger.info(String
						.format("%n%nError starting ApplicationContext. To display the "
								+ "auto-configuration report re-run your application with "
								+ "'debug' enabled."));
			}
			if (this.logger.isDebugEnabled()) {
				this.logger.debug(new ConditionEvaluationReportMessage(this.report));
			}
		}
	}

12.1.2.4 ClearCachesApplicationListener

 源码：主要是清除缓存。

	public void onApplicationEvent(ContextRefreshedEvent event) {
		ReflectionUtils.clearCache();
		clearClassLoaderCaches(Thread.currentThread().getContextClassLoader());
	}

12.1.2.5 SharedMetadataReaderFactoryContextInitializer

 源码：清除缓存

		public void onApplicationEvent(ContextRefreshedEvent event) {
			this.metadataReaderFactory.clearCache();
		}

12.1.2.6 ResourceUrlProvider

 源码：

public void onApplicationEvent(ContextRefreshedEvent event) {
		if (isAutodetect()) {
			this.handlerMap.clear();
			detectResourceHandlers(event.getApplicationContext());
			if (this.handlerMap.isEmpty() && logger.isDebugEnabled()) {
				logger.debug("No resource handling mappings found");
			}
			if (!this.handlerMap.isEmpty()) {
				this.autodetect = false;
			}
		}
	}

 12.2. 启动tomcat的Connector

【六】Spring Boot 源码分析之启动内置Tomcat（Tomcat组件、生命周期简介、一次请求）

12.3.用SimpleApplicationEventMulticaster发布EmbeddedServletContainerInitializedEvent事件

广播出 EmbeddedServletContainerInitializedEvent事件后各个监听器执行的逻辑：

12.3.1 DelegatingApplicationListener

源码：并没有监听EmbeddedServletContainerInitializedEvent事件

public void onApplicationEvent(ApplicationEvent event) {
		if (event instanceof ApplicationEnvironmentPreparedEvent) {
			List> delegates = getListeners(
					((ApplicationEnvironmentPreparedEvent) event).getEnvironment());
			if (delegates.isEmpty()) {
				return;
			}
			this.multicaster = new SimpleApplicationEventMulticaster();
			for (ApplicationListener listener : delegates) {
				this.multicaster.addApplicationListener(listener);
			}
		}
		if (this.multicaster != null) {
			this.multicaster.multicastEvent(event);
		}
	}

12.4 ServerPortInfoApplicationContextInitializer

源码：

	protected void onApplicationEvent(EmbeddedServletContainerInitializedEvent event) {
		String propertyName = getPropertyName(event.getApplicationContext());
		setPortProperty(event.getApplicationContext(), propertyName,
				event.getEmbeddedServletContainer().getPort());
	}