Spring源码:refresh方法解析

前言

在Spring中,refresh方法起着至关重要的作用,也是阅读源码的最合适的入口。它能够帮助Spring完成beanFactory的创建和记载、bean的加载、以及后置处理器的注册等功能。这个方法包括了整个Spring的执行流程和bean的完整生命周期。首先从new ClassPathXmlApplicationContext(“xxx.xml”)开始。

	public ClassPathXmlApplicationContext(
			String[] configLocations, boolean refresh, @Nullable ApplicationContext parent)
			throws BeansException {

		super(parent);
		// 设置资源路径("xxx.xml")
		setConfigLocations(configLocations);
		if (refresh) {
			// 直接调用refresh
			refresh();
		}
	}

refresh方法中层次和逻辑非常清楚,而且包含了ApplicationContext的所有功能。从bean工厂的创建到bean对象的实例化和初始化再到完成Spring容器完成加载,都能在这里找到源码。

	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			// 初始化前的准备工作,主要是一些系统属性、环境变量的校验,比如Spring启动需要某些环境变量,可以在这个地方进行设置和校验
			prepareRefresh();

			// Tell the subclass to refresh the internal bean factory.
			// 获取bean工厂,ConfigurableListableBeanFactory是默认的容器,在这一步会完成工厂的创建以及beanDefinition的读取
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

			// Prepare the bean factory for use in this context.
			// 进入prepareBeanFactory前spring以及完成了对配置的解析,Spring的拓展从这里开始
			prepareBeanFactory(beanFactory);

			try {
				// Allows post-processing of the bean factory in context subclasses.
				// 留给子类覆盖做拓展,这里一般不做任何处理
				postProcessBeanFactory(beanFactory);

				// Invoke factory processors registered as beans in the context.
				// 调用所有的BeanFactoryPostProcessors,将结果存入参数beanFactory中
				invokeBeanFactoryPostProcessors(beanFactory);

				// Register bean processors that intercept bean creation.
				// 注册BeanPostProcessors,这里只是注册,真正的调用是在doGetBean中
				registerBeanPostProcessors(beanFactory);

				// Initialize message source for this context.
				// 初始化消息原,比如国际化
				initMessageSource();

				// Initialize event multicaster for this context.
				// 初始化消息广播器
				initApplicationEventMulticaster();

				// Initialize other special beans in specific context subclasses.
				// 留给子类类初始化其他的bean
				onRefresh();

				// Check for listener beans and register them.
				// 注册监听器
				registerListeners();

				// Instantiate all remaining (non-lazy-init) singletons.
				// 初始化剩下的单例bean,在这里才开始真正的对bean进行实例化和初始化
				finishBeanFactoryInitialization(beanFactory);

				// Last step: publish corresponding event.
				// 完成刷新,通知生命周期处理器刷新过程。
				finishRefresh();
			}
		}
	}

1.prepareRefresh(),Spring初始化前的一些准备工作,主要是一些系统属性、环境变量的校验。设置Spring的活跃状态为以及开始时间。

2.obtainFreshBeanFactory(),初始化bean工厂,其返回的ConfigurableListableBeanFactory内部其实新建了一个DefaultListableBeanFactory(Spring默认的容器,是Spring中功能最完整、最成熟的容器),并设置DefaultListableBeanFactory为全局变量。读取资源文件加载beanDefinition存入容器。

主要的代码是在refreshBeanFactory中,在refreshBeanFactory方法中Spring会new一个DefaultListableBeanFactory 对象,DefaultListableBeanFactory 是Spring中默认的BeanFactory,接着对这个beanFactory进行定制化处理,调用XmlBeanDefinition的loadBeanDefinitions方法从xml文件中加载所有的beanDefinition并加载到这个DefaultListableBeanFactory 中。而这个this.beanFactory = beanFactory则是将该DefaultListableBeanFactory 设置为全局变量,变成整个Spring容器默认的beanFactory。

	protected final void refreshBeanFactory() throws BeansException {
		// 判断是否以及存在BeanFactory,如果已经存在就销毁
		if (hasBeanFactory()) {
			destroyBeans();
			closeBeanFactory();
		}
		try {
			// 创建一个DefaultListableBeanFactory(Spring容器的基础,成熟、功能完善的容器)
			DefaultListableBeanFactory beanFactory = createBeanFactory();
			// 序列化id
			beanFactory.setSerializationId(getId());
			// 定制beanFactory
			customizeBeanFactory(beanFactory);
			loadBeanDefinitions(beanFactory);
			this.beanFactory = beanFactory;
		}
		catch (IOException ex) {
			throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
		}
	}

3.prepareBeanFactory(beanFactory),初始化beanFactory,为beanFactory设置属性,比如添加属性编辑器、对SPEL表达式的支持、Aware回调接口的处理器、忽略的依赖和注册依赖。

	protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// Tell the internal bean factory to use the context's class loader etc.
		// 设置类加载器
		beanFactory.setBeanClassLoader(getClassLoader());
		// 设置对表达式的支持
		beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		// 设置属性编辑器的支持
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// Configure the bean factory with context callbacks.
		// 添加回调接口的支持
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
		// 如果是EnvironmentAware、EmbeddedValueResolverAware等接口的实现类,就不进行自动装配
		// 这些回调接口会通过实现类的setter将自身的一些属性注入
		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.
		// Spring检测到一下接口的实现类时便会将其注入
		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.
		// 添加监听器
		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.
		// 设置环境变量
		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());
		}
	}

4.postProcessBeanFactory(beanFactory),留给子类覆盖做拓展,这里一般不做任何处理
5.invokeBeanFactoryPostProcessors(beanFactory),调用所有的BeanFactoryPostProcessors,将结果存入参数beanFactory中。

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

		// Invoke BeanDefinitionRegistryPostProcessors first, if any.
		Set<String> processedBeans = new HashSet<>();
		// 传进来的beanFactory之前新建的DefaultListableBeanFactory,实现了BeanDefinitionRegistry接口,判断为true
		if (beanFactory instanceof BeanDefinitionRegistry) {
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
			// 存放BeanFactoryPostProcessor的容器
			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
			// 存放BeanDefinitionRegistryPostProcessor的容器
			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
            // 遍历作为参数传进来的beanFactoryPostProcessors
			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
				// 优先调用BeanDefinitionRegistryPostProcessor,并区分开BeanFactoryPostProcessor和BeanDefinitionRegistryPostProcessor
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;
					// 如果是BeanDefinitionRegistryPostProcessor,直接调用postProcessBeanDefinitionRegistry方法
					registryProcessor.postProcessBeanDefinitionRegistry(registry);
					// 存入集合
					registryProcessors.add(registryProcessor);
				}
				else {
					// 普通的BeanFactoryPostProcessor集合
					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.k

			// 下面是开始寻找Spring上下文中的BeanDefinitionRegistryPostProcessor
			// 存放BeanDefinitionRegistryPostProcessor的集合
			List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

			// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
			 /**
			   * 首先处理的是BeanDefinitionRegistryPostProcessor
			  * 1.拿到所有的首先处理的是BeanDefinitionRegistryPostProcessor的beanName
			  * 2.如果BeanDefinitionRegistryPostProcessor实现了PriorityOrdered接口,就添加到currentRegistryProcessors集合中
			  * 3.调用invokeBeanDefinitionRegistryPostProcessors,将结果注册到registry(Spring默认的容器DefaultListableBeanFactory中)
			  * 4.清理空集合,加载调用实现 Ordered的BeanDefinitionRegistryPostProcessor
			  * 5.清理空集合,加载其他BeanDefinitionRegistryPostProcessor
			   */
			String[] postProcessorNames =
					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			// 排序
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			// 排完序后将所有的BeanDefinitionRegistryPostProcessor注册
			registryProcessors.addAll(currentRegistryProcessors);
			// 调用
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			// 清除容器
			currentRegistryProcessors.clear();

			// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
			// 调用实现 Ordered 的 BeanDefinitionRegistryPostProcessors,方法和上面差不多
			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.
			// 循环调用其他的BeanDefinitionRegistryPostProcessors,直到调用完毕
			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.
			invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
			invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
		}

		else {
			// 下面处理非BeanDefinitionRegistry的处理器
			// 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!
		// 拿到所有的BeanFactoryPostProcessor的beanName
		String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

		// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		// 将实现了Ordered、PriorityOrdered接口的、其他的BeanFactoryPostProcessors放在不同容器
		List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		// 遍历beanName,区分不同的BeanFactoryPostProcessors,放在不同的容器
		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.
		// 首先调用实现了PriorityOrdered接口的BeanFactoryPostProcessors
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		// 接着调用实现了BeanFactoryPostProcessors
		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.
		// 最后再调用其他的处理器
		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...
		// 清除缓存
		beanFactory.clearMetadataCache();
	}

在这个方法中主要做三件事:
(1)加载入参的beanFactoryPostProcessors
优先加载BeanDefinitionRegistryPostProcessor类型的,并且会直接调用一次registryProcessor.postProcessBeanDefinitionRegistry(registry)方法,然后分别将BeanDefinitionRegistryPostProcessor类型的和BeanFactoryPostProcessor放入不同类型的容器中。

(2)加载上下文的BeanDefinitionRegistryPostProcessor。

		  * 1.拿到所有的首先处理的是BeanDefinitionRegistryPostProcessor的beanName
		  * 2.如果BeanDefinitionRegistryPostProcessor实现了PriorityOrdered接口,就添加到currentRegistryProcessors集合中
		  * 3.调用invokeBeanDefinitionRegistryPostProcessors,将结果注册到registry(Spring默认的容器DefaultListableBeanFactory中)
		  * 4.清理空集合,加载调用实现 Ordered的BeanDefinitionRegistryPostProcessor
		  * 5.清理空集合,加载其他BeanDefinitionRegistryPostProcessor

(3)加载上下文的BeanFactoryPostProcessor
和第二步顺序一样也是按照PriorityOrdered、Ordered、和其他的BeanFactoryPostProcessor的顺序加载。

6.registerBeanPostProcessors(beanFactory),注册BeanPostProcessors,和调用BeanFactoryPostProcessor的步骤差差不多。不过invokeBeanFactoryPostProcessors会调用后置处理器的方法,而这个仅仅是注册而已,不会调用其中的方法。

final class PostProcessorRegistrationDelegate {

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

		// Invoke BeanDefinitionRegistryPostProcessors first, if any.
		Set<String> processedBeans = new HashSet<>();
		// 传进来的beanFactory之前新建的DefaultListableBeanFactory,实现了BeanDefinitionRegistry接口,判断为true
		if (beanFactory instanceof BeanDefinitionRegistry) {
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
			// 存放BeanFactoryPostProcessor的容器
			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
			// 存放BeanDefinitionRegistryPostProcessor的容器
			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
            // 遍历作为参数传进来的beanFactoryPostProcessors
			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
				// 优先调用BeanDefinitionRegistryPostProcessor,并区分开BeanFactoryPostProcessor和BeanDefinitionRegistryPostProcessor
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;
					// 如果是BeanDefinitionRegistryPostProcessor,直接调用postProcessBeanDefinitionRegistry方法
					registryProcessor.postProcessBeanDefinitionRegistry(registry);
					// 存入集合
					registryProcessors.add(registryProcessor);
				}
				else {
					// 普通的BeanFactoryPostProcessor集合
					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.k

			// 下面是开始寻找Spring上下文中的BeanDefinitionRegistryPostProcessor
			// 存放BeanDefinitionRegistryPostProcessor的集合
			List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

			// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
			 /**
			   * 首先处理的是BeanDefinitionRegistryPostProcessor
			  * 1.拿到所有的首先处理的是BeanDefinitionRegistryPostProcessor的beanName
			  * 2.如果BeanDefinitionRegistryPostProcessor实现了PriorityOrdered接口,就添加到currentRegistryProcessors集合中
			  * 3.调用invokeBeanDefinitionRegistryPostProcessors,将结果注册到registry(Spring默认的容器DefaultListableBeanFactory中)
			  * 4.清理空集合,加载调用实现 Ordered的BeanDefinitionRegistryPostProcessor
			  * 5.清理空集合,加载其他BeanDefinitionRegistryPostProcessor
			   */
			String[] postProcessorNames =
					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			// 排序
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			// 排完序后将所有的BeanDefinitionRegistryPostProcessor注册
			registryProcessors.addAll(currentRegistryProcessors);
			// 调用
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			// 清除容器
			currentRegistryProcessors.clear();

			// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
			// 调用实现 Ordered 的 BeanDefinitionRegistryPostProcessors,方法和上面差不多
			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.
			// 循环调用其他的BeanDefinitionRegistryPostProcessors,直到调用完毕
			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.
			invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
			invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
		}

		else {
			// 下面处理非BeanDefinitionRegistry的处理器
			// 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!
		// 拿到所有的BeanFactoryPostProcessor的beanName
		String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

		// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		// 将实现了Ordered、PriorityOrdered接口的、其他的BeanFactoryPostProcessors放在不同容器
		List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		// 遍历beanName,区分不同的BeanFactoryPostProcessors,放在不同的容器
		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.
		// 首先调用实现了PriorityOrdered接口的BeanFactoryPostProcessors
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		// 接着调用实现了BeanFactoryPostProcessors
		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.
		// 最后再调用其他的处理器
		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...
		// 清楚缓存
		beanFactory.clearMetadataCache();
	}

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

		// 获取所有postProcessor的名称
		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.
		// 注册 BeanPostProcessorChecker,它会在 BeanPostProcessor 实例化期间创建 bean 时记录一条信息消息,即当 bean 不符合所有 BeanPostProcessor 处理的条件时。
		int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
		beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

		// Separate between BeanPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		// 创建不同的集合来区分实现了PriorityOrdered、Ordered和其他BeanPostProcessors
		List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		for (String ppName : postProcessorNames) {
			if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
				priorityOrderedPostProcessors.add(pp);
				// 注册MergedBeanDefinitionPostProcessor类型的
				if (pp instanceof MergedBeanDefinitionPostProcessor) {
					internalPostProcessors.add(pp);
				}
			}
			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				// 实现了Ordered接口
				orderedPostProcessorNames.add(ppName);
			}
			else {
				// 普通的BeanPostProcessor
				nonOrderedPostProcessorNames.add(ppName);
			}
		}

		// First, register the BeanPostProcessors that implement PriorityOrdered.
		// 注册实现了PriorityOrdered接口的BeanPostProcessors
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

		// Next, register the BeanPostProcessors that implement Ordered.
		// 注册实现了Ordered接口的BeanPostProcessors
		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);
			}
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		registerBeanPostProcessors(beanFactory, orderedPostProcessors);

		// Now, register all regular BeanPostProcessors.
		// 注册普通的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);
			}
		}
		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).
		// 添加应用监听器
		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
	}

7.initMessageSource(),初始化Message源,对不同语言的消息体进行国际化处理。

8.initApplicationEventMulticaster(),初始化消息广播器

9.onRefresh(),留给子类初始化其他的bean

10.registerListeners(),注册监听器

11.finishBeanFactoryInitialization(beanFactory),这个方法也是重点,Spring就是在这里完成非懒加载的单例bean的加载的。其中bean的加载和初始化就是在preInstantiateSingletons中,如果getBean的结果为null,Spring就会通过beanName在工厂中拿到对应的beaDefinition,开始加载bean。

	public void preInstantiateSingletons() throws BeansException {
		if (logger.isDebugEnabled()) {
			logger.debug("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.
		// 获取所有的beanName
		List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);

		// Trigger initialization of all non-lazy singleton beans...
		// 遍历BeanName
		for (String beanName : beanNames) {
			RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
			// 如果BeanDefinition符合单例、非懒加载、非抽象的类,就开始加载bean
			if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
				if (isFactoryBean(beanName)) {
					// 获取bean
					Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
					// FactoryBean是特殊的bean,需要特殊处理。FactoryBean是通过getObject方法获取真正的对象
					if (bean instanceof FactoryBean) {
						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 {
					// 获取bean
					getBean(beanName);
				}
			}
		}

		// Trigger post-initialization callback for all applicable beans...
		// 触发所有bean的回调
		for (String beanName : beanNames) {
			Object singletonInstance = getSingleton(beanName);
			if (singletonInstance instanceof SmartInitializingSingleton) {
				SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
				if (System.getSecurityManager() != null) {
					AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
						smartSingleton.afterSingletonsInstantiated();
						return null;
					}, getAccessControlContext());
				}
				else {
					smartSingleton.afterSingletonsInstantiated();
				}
			}
		}
	}

12finishRefresh(),完成refresh方法,通知生命周期处理器刷新过程,并发出广播通知别人。

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