Spring注解开发（七）Spring容器创建

简单看一下Spring IOC容器创建的步骤：
注解相关的Spring容器为AnnotationConfigApplicationContext 。

下图是AnnotationConfigApplicationContext的主要实现及继承类图：

从图中可以看到：

• AnnotationConfigApplicationContext继承GenericApplicationContext这个通用应用上下文，GenericApplicationContext内部定义了一个DefaultListableBeanFactory实例。
• GenericApplicationContext实现了BeanDefinitionRegistry接口，所以可以通过AnnotationConfigApplicationContext实例注册bean defintion，然后调用refresh()方法来初始化上下文。

	@Override
	public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
			throws BeanDefinitionStoreException {

		this.beanFactory.registerBeanDefinition(beanName, beanDefinition);
	}

• AnnotationConfigApplicationContext继承AbstractApplicationContext，AbstractApplicationContext提供了ApplicationContext的抽象实现。

从new AnnotationConfigApplicationContext简单示例查看Spring容器创建过程。

  AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(ExtConfig.class);

//创建一个AnnotationConfigApplicationContext，从给定的一个或多个带注释的类，例如 {@Configuration}类获取bean定义信息并自动刷新上下文。 
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
       //初始化bean读取器和扫描器;
       //调用父类GenericApplicationContext无参构造函数，初始化一个BeanFactory: DefaultListableBeanFactory beanFactory = new  DefaultListableBeanFactory()
		this();
		//注册配置类，此处annotatedClasses为ExtConfig.class
		register(annotatedClasses);
		//刷新容器上下文
		refresh();
	}

This方法

	public AnnotationConfigApplicationContext() {
	    //在IOC容器中初始化一个 注解bean读取器AnnotatedBeanDefinitionReader
		this.reader = new AnnotatedBeanDefinitionReader(this);
		//在IOC容器中初始化一个 按类路径扫描注解bean的 扫描器
		this.scanner = new ClassPathBeanDefinitionScanner(this);
	}

AnnotationConfigApplicationContext继承自AbstractApplicationContext，会先调用AbstractApplicationContext的构造函数，初始化一个DefaultListableBeanFactory

public GenericApplicationContext() {
        //初始化BeanFactory
		this.beanFactory = new DefaultListableBeanFactory();
	}

看一下new AnnotatedBeanDefinitionReader(this)的实现，源码如下：

public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
		Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
		Assert.notNull(environment, "Environment must not be null");
		this.registry = registry;
		this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);
		//此处向容器中注册了很多基础的的处理器，比如像refresh第5步的ConfigurationClassPostProcessor就是在此处注册的，还有第六步的AutowiredAnnotationProcessor等
		AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
	}

register方法

如上Debug路径，最终调用的为AnnotatedBeanDefinitionReader的doRegisterBean方法：
此处向容器中注册

<T> void doRegisterBean(Class<T> annotatedClass, @Nullable Supplier<T> instanceSupplier, @Nullable String name,
			@Nullable Class<? extends Annotation>[] qualifiers, BeanDefinitionCustomizer... definitionCustomizers) {
        //将Bean配置类信息包装为AnnotatedGenericBeanDefinition对象
        //在此构造方法中新建了一个StandardAnnotationMetadata将配置类的注解信息属性赋值给AnnotatedGenericBeanDefinition的属性metadata
		AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
		//判断@Conditional装配条件是否需要跳过注册
		if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
			return;
		}

		abd.setInstanceSupplier(instanceSupplier);
		 //解析bean作用域(singleton)，如果有@Scope注解则解析@Scope，没有则取默认值singleton
		ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
		//设置作用域，此处取默认singleton
		abd.setScope(scopeMetadata.getScopeName());
		//获取beanName，如果没有则生成类名首字母小写作为beanName
		String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
       //处理通用定义注解，有这几个：Lazy；Primary；DependsOn；Role；Description
		AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
		//@Qualifier处理
		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));
				}
			}
		}
		for (BeanDefinitionCustomizer customizer : definitionCustomizers) {
			customizer.customize(abd);
		}
        //根据beanName和beanDefinition封装一个beanhold,持有具有名称和别名的BeanDefinition。
		BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
		//创建代理对象beanDefinition，此处scopedProxyMode为ScopedProxyMode.NO，原样返回
		definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
		/*向BeanFactory注册该beanDefinition，将beanDefinition注册到容器中
		 *this.beanFactory.registerBeanDefinition(beanName, beanDefinition);
		 *----调用到DefaultListableBeanFactory的registerBeanDefinition方法
		 *将beanName和beanDefinition放到其内部维护的一个Map，并将beanName放到List集合中
		 *this.beanDefinitionMap.put(beanName, beanDefinition);
		 *this.beanDefinitionNames.add(beanName);
		 */
		BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
	}

从上可以看到register方法完成了配置类的解析和注册。

refresh方法

refresh方法在AbstractApplicationContext被调用，源码如下：

	@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			//1.刷新前的预处理
			prepareRefresh();
			//2.获取BeanFactory；默认实现是DefaultListableBeanFactory，在创建容器的时候创建的
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
			//3. BeanFactory的预准备工作（BeanFactory进行一些设置）
			prepareBeanFactory(beanFactory);
			try {
				// 4.BeanFactory准备工作完成后进行的后置处理工作
				postProcessBeanFactory(beanFactory);
				// 5.执行BeanFactoryPostProcessor的方法
				invokeBeanFactoryPostProcessors(beanFactory);
				//6.注册BeanPostProcessor（Bean的后置处理器）
				registerBeanPostProcessors(beanFactory);
				// 7.初始化MessageSource组件（做国际化功能；消息绑定，消息解析）
				initMessageSource();
				// 8.初始化事件派发器
				initApplicationEventMulticaster();
				// 9.留给子容器（子类），子类重写这个方法，在容器刷新的时候可以自定义逻辑
				onRefresh();
				// 10.给容器中将所有项目里面的ApplicationListener注册进来
				registerListeners();
				// 11.初始化所有剩下的单实例bean
				finishBeanFactoryInitialization(beanFactory);
				// 12.完成BeanFactory的初始化创建工作；IOC容器就创建完成，发布容器创建完成事件
				finishRefresh();
			}
		........
		}
	}

1. prepareRefresh()刷新前的预处理

	protected void prepareRefresh() {
		// 启动时间
		this.startupDate = System.currentTimeMillis();
        //设置启动标识
		this.closed.set(false);
		this.active.set(true);
        ......
		// 初始化在上下文环境中的占位符属性源.
		//初始化一些属性设置;空方法由子类自定义个性化的属性设置方法；
		initPropertySources();
		// 检验属性合法性，是否不为空等
		getEnvironment().validateRequiredProperties();

		// 创建保存容器早期事件监听的容器
		if (this.earlyApplicationListeners == null) {
			this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
		}
        .....
		//保存容器中的一些早期的事件，将在多播器可用时发布
		this.earlyApplicationEvents = new LinkedHashSet<>();
	}

• 设置启动标识，容器状态设置
• 初始化在上下文环境中的占位符属性源.
• 当前环境的一些校验等.

2. obtainFreshBeanFactory获取BeanFactory

protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
		refreshBeanFactory();
		return getBeanFactory();
	}

• refreshBeanFactory()

protected final void refreshBeanFactory() throws IllegalStateException {
       //设置刷新标识为true
		if (!this.refreshed.compareAndSet(false, true)) {
			throw new IllegalStateException(
					"GenericApplicationContext does not support multiple refresh attempts: just call 'refresh' once");
		}
		//设置序列化编码
		this.beanFactory.setSerializationId(getId());
	}

• getBeanFactory()

@Override
	public final ConfigurableListableBeanFactory getBeanFactory() {
	//返回默认创建的DefaultListableBeanFactory
		return this.beanFactory;
	}

• 设置容器刷新标识为true
• 获取DefaultListableBeanFactory

3. prepareBeanFactory BeanFactory的预准备工作

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// 设置beanFactory使用当前上下文的类加载器等。
		beanFactory.setBeanClassLoader(getClassLoader());
		//设置beanFactory的表达式处理器，内部创建了一个SpelExpressionParser用于处理#{**}
		beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		//为beanFactory增加一个默认的PropertyEditor,更准确应该是属性转换器，比如从String到Date类型的转化
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// 添加ApplicationContextAwareProcessor
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
		//设置几个忽略自动装配的接口
		beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
		beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
		beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
		beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
		beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
		beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);

		//注册可以解析的自动装配，能直接在任何组件中自动注入：BeanFactory、ResourceLoader、ApplicationEventPublisher、ApplicationContext
        //其他组件中可以通过 @autowired 直接注册使用
		beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
		beanFactory.registerResolvableDependency(ResourceLoader.class, this);
		beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
		beanFactory.registerResolvableDependency(ApplicationContext.class, this);

		// 添加BeanPostProcessor后置处理器，在bean初始化前后的一些工作
		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));

		// 如果包含LoadTimeWeaver，（AspectJ支持）
		if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
		//添加后置处理器
    	beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
			// Set a temporary ClassLoader for type matching.
			beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
		}
		//注册默认的environment
		//environment
		if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
			beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
		}
		//systemProperties
		if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
			beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
		}
		//systemEnvironment
		if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
			beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
		}
	}

-设置beanFactory的各种属性

4. postProcessBeanFactory(beanFactory) BeanFactory后置处理

//在AbstractApplicationContext里是空实现,该方法交由子类覆盖去实现
protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
	}

看一下两个子类的实现：

• GenericWebApplicationContext

	/**
	 * 注册ServletContextAwareProcessor.
	 * @see ServletContextAwareProcessor
	 */
	@Override
	protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		if (this.servletContext != null) {
		    //添加ServletContextAwareProcessor到beanFactory容器中
			beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext));
			//忽略装配接口ServletContextAware
			beanFactory.ignoreDependencyInterface(ServletContextAware.class);
		}
        //注册WEB应用特定的scope到 beanFactory 中
		WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);
		//注册WEB应用特定的Environment bean到beanFactory中
		WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext);
	}

• AbstractRefreshableWebApplicationContext

	@Override
	protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
    	//添加ServletContextAwareProcessor到beanFactory容器中
		beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext, this.servletConfig));
		//忽略装配接口ServletContextAware和ServletConfigAware
		beanFactory.ignoreDependencyInterface(ServletContextAware.class);
		beanFactory.ignoreDependencyInterface(ServletConfigAware.class);
        //注册WEB应用特定的scope到 beanFactory 中
		WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);
		//注册WEB应用特定的Environment bean到beanFactory中
		WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext, this.servletConfig);
	}

5.invokeBeanFactoryPostProcessors 执行BeanFactory后置处理器

先介绍两个接口：

• BeanFactoryPostProcessor：用来修改Spring容器中已经存在的bean的定义，使用ConfigurableListableBeanFactory对bean进行处理
• BeanDefinitionRegistryPostProcessor：继承BeanFactoryPostProcessor，作用跟BeanFactoryPostProcessor一样，只不过是使用BeanDefinitionRegistry对bean进行处理
  在Spring容器中找出实现了BeanFactoryPostProcessor接口的processor并执行。Spring容器会委托给PostProcessorRegistrationDelegate的invokeBeanFactoryPostProcessors方法执行。

注：

1. 在springboot的web程序初始化AnnotationConfigServletWebServerApplicationContext容器时，会初始化内部属性AnnotatedBeanDefinitionReader reader，这个reader构造的时候会在BeanFactory中注册一些post processor，包括BeanPostProcessor和BeanFactoryPostProcessor(比如ConfigurationClassPostProcessor、AutowiredAnnotationBeanPostProcessor)。

AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);

2. 在使用mybatis时，一般配置了MapperScannerConfigurer的bean，这个bean就是继承的BeanDefinitionRegistryPostProcessor，所以也是这个地方把扫描的mybatis的接口注册到容器中的。

接下来看invokeBeanFactoryPostProcessors做了什么：

//beanFactoryPostProcessors此处(一般)为空，后序会通过类型获取
public static void invokeBeanFactoryPostProcessors(
			ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {

		// Invoke BeanDefinitionRegistryPostProcessors first, if any.
		Set<String> processedBeans = new HashSet<>();
        //判断是否为BeanDefinitionRegistry类型
		if (beanFactory instanceof BeanDefinitionRegistry) {
     		//强转
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
           
			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;
					//调用重写的postProcessBeanDefinitionRegistry方法
					registryProcessor.postProcessBeanDefinitionRegistry(registry);
					//添加到集合中
					registryProcessors.add(registryProcessor);
				}
				else {
				    //如果不是BeanDefinitionRegistryPostProcessor类型，则添加到regularPostProcessors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.
			//用于保存临时的BeanDefinitionRegistryPostProcessor
			List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

			// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
			//首先从容器中获取BeanDefinitionRegistryPostProcessor类型的postProcessorNames 
			/* Spring有一个内部的BeanFactoryPostProcessor 
			 * ID：org.springframework.context.annotation.internalConfigurationAnnotationProcessor；
		     * 类型为BeanDefinitionRegistryPostProcessor，实现类为ConfigurationClassPostProcessor；
		     * 负责解析处理所有@Configuration标签类，并将Bean定义注册到BeanFactory中
		    */
			String[] postProcessorNames =
					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
           //此处postProcessorNames长度为1，ppName为
			for (String ppName : postProcessorNames) {
			//先处理实现PriorityOrdered(优先级)接口的
				if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				   //创建了ConfigurationClassPostProcessor类，并放入集合
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			//按照优先级排序
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			//添加到集合中
			registryProcessors.addAll(currentRegistryProcessors);
			//执行所有存储在currentRegistryProcessors中的后置方法postProcessBeanDefinitionRegistry
			//在此处执行ConfigurationClassPostProcessor的postProcessBeanDefinitionRegistry方法，处理    Component，PropertySources，ComponentScans等，并注册beanDefinition到容器中
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			//清空临时集合
			currentRegistryProcessors.clear();

			// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
			//执行实现了Ordered接口的BeanDefinitionRegistryPostProcessor
			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.
			//最后处理剩下的BeanDefinitionRegistryPostProcessors 
			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.
			//执行子类实现的postProcessBeanFactory方法
			invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
			invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
		}

		else {
			// Invoke factory processors registered with the context instance.
			//如果不是BeanDefinitionRegistry 只需要调用其回调函数（postProcessBeanFactory()）即可
			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!
		//获取BeanFactoryPostProcessor类型
		String[] postProcessorNames =
				beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

		// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		for (String ppName : postProcessorNames) {
			//先判断是否是上面处理过的
			if (processedBeans.contains(ppName)) {
				// skip - already processed in first phase above
			}
			//实现了PriorityOrdered接口的被放入优先级集合
			else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
			}
			//实现了Ordered接口
			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				orderedPostProcessorNames.add(ppName);
			}
			else {
		     	//其他类型的
				nonOrderedPostProcessorNames.add(ppName);
			}
		}

		// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
		//根据优先级排序
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		//先执行实现了PriorityOrdered接口的
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>();
		for (String postProcessorName : orderedPostProcessorNames) {
			orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		//执行实现了Ordered接口的
		invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

		// Finally, invoke all other BeanFactoryPostProcessors.
		List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
		for (String postProcessorName : nonOrderedPostProcessorNames) {
			nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		//其他符合条件的
		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();
	}

6. registerBeanPostProcessors 注册BeanPostProcessor

进入PostProcessorRegistrationDelegate类的registerBeanPostProcessors方法，源码如下：

public static void registerBeanPostProcessors(
			ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
        //获取所有BeanPostProcessor类型的beanName
        //此处获取了org.springframework.context.annotation.internalAutowiredAnnotationProcessor（AutowiredAnnotationProcessor）和
        //org.springframework.context.annotation.internalCommonAnnotationProcessor（CommonAnnotationBeanPostProcessor ）
		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.
		//获取所有的beanPostProcessor数量
		int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
		//注册BeanPostProcessorChecker,其主要的作用是在bean的实例化期间进行日志的记录
		beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

		// Separate between BeanPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		//按照优先级和内部Bean放入各个集合
		for (String ppName : postProcessorNames) {
			if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
     			//创建实例
				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);
		//处理实现了PriorityOrdered接口的
		registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

		// Next, register the BeanPostProcessors that implement Ordered.
		List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
		for (String ppName : orderedPostProcessorNames) {
     		//创建实例对象
			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
			orderedPostProcessors.add(pp);
			if (pp instanceof MergedBeanDefinitionPostProcessor) {
				internalPostProcessors.add(pp);
			}
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		//处理实现了Ordered接口的
		registerBeanPostProcessors(beanFactory, orderedPostProcessors);

		// Now, register all regular BeanPostProcessors.
		List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
		for (String ppName : nonOrderedPostProcessorNames) {
    		//创建实例对象
			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
			nonOrderedPostProcessors.add(pp);
			if (pp instanceof MergedBeanDefinitionPostProcessor) {
				internalPostProcessors.add(pp);
			}
		}
		//调用两个接口都没有实现的
		registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);

		// Finally, re-register all internal BeanPostProcessors.
		sortPostProcessors(internalPostProcessors, beanFactory);
		//最后处理所有的内部的BeanPostProcessors
		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).
		//加入ApplicationListenerDetector
		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
	}

7. initMessageSource 初始化MessageSource组件

protected void initMessageSource() {
        //获取BeanFactory
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		//查找是否包含messageSource类
		if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
		   //获取该类的实例Bean
			this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
			// Make MessageSource aware of parent MessageSource.
			//如果容器的parent属性不为空（此处为空）并且messageSource 是HierarchicalMessageSource类型
			if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
				//强转
				HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
				if (hms.getParentMessageSource() == null) {
					// Only set parent context as parent MessageSource if no parent MessageSource
					// registered already.
					//设置容器的ParentMessageSource，如果为空，则返回父容器本身
					hms.setParentMessageSource(getInternalParentMessageSource());
				}
			}
			if (logger.isTraceEnabled()) {
				logger.trace("Using MessageSource [" + this.messageSource + "]");
			}
		}
		else {
			// Use empty MessageSource to be able to accept getMessage calls.
			使用空的MessageSource去接受getMessage调用
			DelegatingMessageSource dms = new DelegatingMessageSource();
			dms.setParentMessageSource(getInternalParentMessageSource());
			this.messageSource = dms;
			beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
			if (logger.isTraceEnabled()) {
				logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");
			}
		}
	}

8. initApplicationEventMulticaster 初始化事件派发器

protected void initApplicationEventMulticaster() {
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
         //如果包含applicationEventMulticaster类型的bean	
		if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
			//设置属性为实例化的对象
			this.applicationEventMulticaster =
					beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
			if (logger.isTraceEnabled()) {
				logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
			}
		}
		else {
		    //没有则新建一个SimpleApplicationEventMulticaster，并注册。
			this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
			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() + "]");
			}
		}
	}

9. onRefresh 容器刷新自定义逻辑

	protected void onRefresh() throws BeansException {
		// For subclasses: do nothing by default.
	}

一个模板方法，不同的Spring容器做不同的事情。
比如SpringBoot的web程序的容器ServletWebServerApplicationContext中会调用createWebServer方法去创建内置的Servlet容器。

	@Override
	protected void onRefresh() {
		super.onRefresh();
		try {
			createWebServer();
		}catch (Throwable ex) {
			throw new ApplicationContextException("Unable to start web server", ex);
		}
	}

10.registerListeners 注册ApplicationListener

protected void registerListeners() {
		// Register statically specified listeners first.
		//注册静态指定的listeners 。
		//获取ApplicationListeners并注册到事件派发器上（此处为空）
		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!
		//获取所有ApplicationListener类型的BeanName，并添加到事件派发器上
		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...
		//此处发布早期的容器事件（此处为空）
		Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
		this.earlyApplicationEvents = null;
		if (earlyEventsToProcess != null) {
			for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
               //执行onApplication方法
				getApplicationEventMulticaster().multicastEvent(earlyEvent);
			}
		}
	

11. finishBeanFactoryInitialization 初始化剩下的单实例bean（非Lazy）

实例化BeanFactory中已经被注册但是未实例化的所有实例(懒加载的不需要实例化)。比如invokeBeanFactoryPostProcessors方法中根据各种注解解析出来的类，在这个时候都会被初始化。实例化的过程各种BeanPostProcessor开始起作用。

protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
		// Initialize conversion service for this context.
		//为bean工厂设置ConversionService实例（此处为空）
		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.
		//如果beanFactory之前没有注册嵌入值解析器，则注册默认的嵌入值解析器：主要用于注解属性值的解析
		if (!beanFactory.hasEmbeddedValueResolver()) {
			beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
		}

		// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
		//初始化LoadTimeWeaverAware类型对象（此处为空）
		String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
		for (String weaverAwareName : weaverAwareNames) {
			getBean(weaverAwareName);
		}
		// Stop using the temporary ClassLoader for type matching.
		//将临时的Classloader置为空
		beanFactory.setTempClassLoader(null);
		// Allow for caching all bean definition metadata, not expecting further changes.
		//把bean定义元数据信息保存，下一步将实例化Bean，不希望再有其他变动
		beanFactory.freezeConfiguration();
		// Instantiate all remaining (non-lazy-init) singletons.
		//实例化所有剩下的非lazy的单例Bean
		beanFactory.preInstantiateSingletons();
	}

beanFactory.preInstantiateSingletons()源码如下：

@Override
	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.
		//获取BeanNames
		List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);

		// Trigger initialization of all non-lazy singleton beans...
		//遍历并实例化Bean
		for (String beanName : beanNames) {
		    //获取Bean定义信息
			RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
			//判断不是抽象，懒加载并且是单例的Bean进入下面创建环节
			if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
				//判断是否为FactoryBean
				if (isFactoryBean(beanName)) {
				    //获取FactoryBean（在Spring注解开发第一章中有说明&获取的是FactoryBean本身）
					Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
					if (bean instanceof FactoryBean) {
						final FactoryBean<?> factory = (FactoryBean<?>) bean;
						boolean isEagerInit;
						//判断是否需要急切的被初始化
						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 {
				//如果beanName对应的bean不是FactoryBean，通过beanName获取bean实例
					getBean(beanName);
				}
			}
		}

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

12.finishRefresh 完成BeanFactory的初始化创建工作

	protected void finishRefresh() {
		// Clear context-level resource caches (such as ASM metadata from scanning).
		//清空容器级别的缓存信息
		clearResourceCaches();
		// Initialize lifecycle processor for this context.
		//初始化生命周期处理器，并设置到Spring容器中(LifecycleProcessor)
		initLifecycleProcessor();
		// Propagate refresh to lifecycle processor first.
		//调用生命周期处理器的onRefresh方法，这个方法会找出Spring容器中实现了SmartLifecycle接口的类并进行start方法的调用
		getLifecycleProcessor().onRefresh();
		// Publish the final event.
		//发布容器完成刷新时间
		publishEvent(new ContextRefreshedEvent(this));
		// Participate in LiveBeansView MBean, if active.
		LiveBeansView.registerApplicationContext(this);
	}