Spring启动流程refresh()源码深入解析

Z时代
2024-01-10
分类：综合

一、Spring容器的refresh()

spring version:4.3.12 ，尚硅谷Spring注解驱动开发—源码部分


//refresh():543, AbstractApplicationContext (org.springframework.context.support) 
public void refresh() throws BeansException, IllegalStateException {
 synchronized (this.startupShutdownMonitor) {
  //1 刷新前的预处理
  prepareRefresh();
  //2 获取BeanFactory；刚创建的默认DefaultListableBeanFactory
  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；
   // 4.1）、抽象的方法，当前未做处理。子类通过重写这个方法来在BeanFactory创建并预准备完成以后做进一步的设置
  postProcessBeanFactory(beanFactory); 
 /**************************以上是BeanFactory的创建及预准备工作 ****************/
  // 5 执行BeanFactoryPostProcessor的方法；
//BeanFactoryPostProcessor：BeanFactory的后置处理器。在BeanFactory标准初始化之后执行的；
//他的重要两个接口：BeanFactoryPostProcessor、BeanDefinitionRegistryPostProcessor
  invokeBeanFactoryPostProcessors(beanFactory);
  //6 注册BeanPostProcessor（Bean的后置处理器）
  registerBeanPostProcessors(beanFactory);
  // 7 initMessageSource();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 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；
  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();
  }
 }
 }

1 、prepareRefresh()刷新前的预处理;


//刷新前的预处理;
protected void prepareRefresh() {
 this.startupDate = System.currentTimeMillis();
 this.closed.set(false);
 this.active.set(true);
 if (logger.isInfoEnabled()) {
 logger.info("Refreshing " + this);
 }
 // 初始化一些属性设置;子类自定义个性化的属性设置方法；
 initPropertySources(); 
 // 校验配置文件的属性，合法性
 getEnvironment().validateRequiredProperties();
 //保存容器中的一些事件
 this.earlyApplicationEvents = new LinkedHashSet<ApplicationEvent>();
}

2、 obtainFreshBeanFactory();创建了一个BeanFactory


protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
 refreshBeanFactory(); //创建了一个this.beanFactory = new DefaultListableBeanFactory();设置了序列化的ID
 //返回刚才创建的DefaultListableBeanFactory
 ConfigurableListableBeanFactory beanFactory = getBeanFactory();
 if (logger.isDebugEnabled()) {
 logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
 }
 return beanFactory;
}

3、 BeanFactory的预准备工作


protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
 // 1）、设置BeanFactory的类加载器
 beanFactory.setBeanClassLoader(getClassLoader());
 // 1）、设置支持表达式解析器
 beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
 beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
 // 2）、添加部分BeanPostProcessor【ApplicationContextAwareProcessor】
 beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
 // 3）、设置忽略的自动装配的接口EnvironmentAware、EmbeddedValueResolverAware、xxx；
 // 这些接口的实现类不能通过类型来自动注入
 beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
 beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
 beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
 beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
 beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
 beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
 // 4）、注册可以解析的自动装配；我们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下面方式直接注册使用
 @autowired 
 BeanFactory beanFactory */
 beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
 beanFactory.registerResolvableDependency(ResourceLoader.class, this);
 beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
 beanFactory.registerResolvableDependency(ApplicationContext.class, this);
 // 5）、添加BeanPostProcessor【ApplicationListenerDetector】后置处理器，在bean初始化前后的一些工作
 beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
 // 6）、添加编译时的AspectJ；
 if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
 beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
 // Set a temporary ClassLoader for type matching.
 beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
 }
 // 7）、给BeanFactory中注册一些能用的组件；
 if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
 // 环境信息ConfigurableEnvironment
 beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
 }
 //系统属性，systemProperties【Map<String, Object>】
 if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
 beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
 }
 //系统环境变量systemEnvironment【Map<String, Object>】
 if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
 beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
 }
}

5 执行BeanFactoryPostProcessor的后置处理器方法（BeanFactory）；


protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
 //执行BeanFactoryPostProcessor的方法
 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()));
 }
}

5.1 执行invokeBeanFactoryPostProcessors


public static void invokeBeanFactoryPostProcessors(
 ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
 // Invoke BeanDefinitionRegistryPostProcessors first, if any.
 Set<String> processedBeans = new HashSet<String>();
 // 判断beanFatory类型
 if (beanFactory instanceof BeanDefinitionRegistry) {
 BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
 List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>();
 List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>();
 //得到所有的BeanFactoryPostProcessor 遍历
 for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
  if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
  BeanDefinitionRegistryPostProcessor registryProcessor =
   (BeanDefinitionRegistryPostProcessor) postProcessor;
  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<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();
 //从容器中获取所有的BeanDefinitionRegistryPostProcessor，
 String[] postProcessorNames =
  beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
 // 第一步，先执行实现了PriorityOrdered接口的BeanDefinitionRegistryPostProcessor
 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);
 registryProcessors.addAll(currentRegistryProcessors);
 //执行BeanDefinitionRegistryPostProcessor的 postProcessor.postProcessBeanDefinitionRegistry(registry)
 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
 currentRegistryProcessors.clear();
 // 在执行实现了Ordered顺序接口的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);
  }
 }
 //排序
 sortPostProcessors(currentRegistryProcessors, beanFactory);
 registryProcessors.addAll(currentRegistryProcessors);
 //执行postProcessor.postProcessBeanDefinitionRegistry(registry)
 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
 currentRegistryProcessors.clear();
 // 最后执行没有实现任何优先级或者是顺序接口的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();
 }
 // 现在执行 BeanFactoryPostProcessor的postProcessBeanFactory()方法
 invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
 invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
 }
 else {
 // Invoke factory processors registered with the context instance.
 invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
 }
 //再执行BeanFactoryPostProcessor的方法
 //1）、获取所有的BeanFactoryPostProcessor 和执行BeanDefinitionRegistryPostProcessors的接口逻辑一样
 String[] postProcessorNames =
 beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
 List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
 List<String> orderedPostProcessorNames = new ArrayList<String>();
 List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
 //把BeanFactoryPostProcessor 分类
 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);
 }
 }
 // 2）、看先执行实现了PriorityOrdered优先级接口的BeanFactoryPostProcessor、
 sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
 invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
 // 3）、在执行实现了Ordered顺序接口的BeanFactoryPostProcessor；
 List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
 for (String postProcessorName : orderedPostProcessorNames) {
 orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
 }
 sortPostProcessors(orderedPostProcessors, beanFactory);
 invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
 // 4）、最后执行没有实现任何优先级或者是顺序接口的BeanFactoryPostProcessor；
 List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();
 for (String postProcessorName : nonOrderedPostProcessorNames) {
 nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
 }
 invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
 beanFactory.clearMetadataCache();
}

6、注册BeanPostProcessor（Bean的后置处理器）

bean的创建拦截器

不同接口类型的BeanPostProcessor；在Bean创建前后的执行时机是不一样的

BeanPostProcessor、

DestructionAwareBeanPostProcessor、

InstantiationAwareBeanPostProcessor、在createBean()方法中处理的，bean创建之前调用的

SmartInstantiationAwareBeanPostProcessor、

MergedBeanDefinitionPostProcessor【internalPostProcessors】（bean创建完成后调用，11章节中）


registerBeanPostProcessors(beanFactory);


public static void registerBeanPostProcessors(
 ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
//1）、获取所有的 BeanPostProcessor;后置处理器都默认可以通过PriorityOrdered、Ordered接口来执行优先级
 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
  //检查器，检查所有的BeanPostProcessor
 int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
 beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
 // Separate between BeanPostProcessors that implement PriorityOrdered,
 // Ordered, and the rest.
 List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
 List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();
 List<String> orderedPostProcessorNames = new ArrayList<String>();
 List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
 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);
  }
 }
 /* 2）、先注册PriorityOrdered优先级接口的BeanPostProcessor；
   把每一个BeanPostProcessor；添加到BeanFactory中
   beanFactory.addBeanPostProcessor(postProcessor);*/
 sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
 registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
 // 3）、再注册Ordered接口的
 List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();
 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);
 // 4）、最后注册没有实现任何优先级接口的
 List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
 for (String ppName : nonOrderedPostProcessorNames) {
  BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
  nonOrderedPostProcessors.add(pp);
  if (pp instanceof MergedBeanDefinitionPostProcessor) {
   internalPostProcessors.add(pp);
  }
 }
 registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
 // 5）、最终注册MergedBeanDefinitionPostProcessor；
 sortPostProcessors(internalPostProcessors, beanFactory);
 registerBeanPostProcessors(beanFactory, internalPostProcessors);
 // 6）、注册一个ApplicationListenerDetector；判断创建完成的bean是否监听器
 /* 在Bean创建完成后ApplicationListenerDetector.postProcessAfterInitialization()中检查是否是ApplicationListener 类型，如果是applicationContext.addApplicationListener((ApplicationListener<?>) bean);如果是添加到容器中 */
 beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}

7、initMessageSource();国际化

初始化MessageSource组件（做国际化功能；消息绑定，消息解析）；


protected void initMessageSource() {
 // 1）、获取BeanFactory
 ConfigurableListableBeanFactory beanFactory = getBeanFactory();
 /* 
 2）、看容器中是否有id为messageSource的，类型是MessageSource的组件
   如果有赋值给messageSource，如果没有自己创建一个DelegatingMessageSource；
   MessageSource作用：取出国际化配置文件中的某个key的值；能按照区域信息获取；
 */
 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 {
  // 如果没有自己创建一个DelegatingMessageSource；
  DelegatingMessageSource dms = new DelegatingMessageSource();
  dms.setParentMessageSource(getInternalParentMessageSource());
  this.messageSource = dms;
  //把创建好的messageSource注册到容器中，以后获取国际化配置文件的值的时候，可以自动注入MessageSource； 
  //注入后通过这个方法使用MessageSource.getMessage(String code, Object[] args, String defaultMessage, Locale locale);
  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、初始化事件派发器initApplicationEventMulticaster()


protected void initApplicationEventMulticaster() {
 //1）、获取BeanFactory
 ConfigurableListableBeanFactory beanFactory = getBeanFactory();
 //判断容器中是否有applicationEventMulticaster 的这个bean ,如果有获取，没有创建
 if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
  //2）、从BeanFactory中获取applicationEventMulticaster的ApplicationEventMulticaster；
  this.applicationEventMulticaster =
   beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
  if (logger.isDebugEnabled()) {
   logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
  }
 }
 else {
  //3) 个SimpleApplicationEventMulticaster 类型的 applicationEventMulticaster
  this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
  //4）、将创建的ApplicationEventMulticaster添加到BeanFactory中，以后其他组件直接自动注入
  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();留给子容器（子类）

1、子类重写AbstractApplicationContext.onRefresh()这个方法，在容器刷新的时候可以自定义逻辑；

10、registerListeners();检查和注册 Listener

将所有项目里面的ApplicationListener注册到容器中；


protected void registerListeners() {
 //1、从容器中拿到所有的ApplicationListener
 for (ApplicationListener<?> listener : getApplicationListeners()) {
  //2、将每个监听器添加到事件派发器中；
  getApplicationEventMulticaster().addApplicationListener(listener);
 }
 // 1.获取所有的ApplicationListener
 String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
 for (String listenerBeanName : listenerBeanNames) {
  //2、将每个监听器添加到事件派发器中；
  getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
 }
 // earlyApplicationEvents 中保存之前的事件，
 Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
 this.earlyApplicationEvents = null;
 if (earlyEventsToProcess != null) {
  for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
   //3、派发之前步骤产生的事件；
   getApplicationEventMulticaster().multicastEvent(earlyEvent);
  }
 }
}

11、初始化所有剩下的单实例bean；finishBeanFactoryInitialization(beanFactory);


protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
 // 类型装换器
 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));
 }
 //值解析器
 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.
 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();
 // 初始化剩下的单实例bean
 beanFactory.preInstantiateSingletons();
}

11.1 beanFactory.preInstantiateSingletons()初始化剩下的单实例bean


//preInstantiateSingletons():781, DefaultListableBeanFactory 
public void preInstantiateSingletons() throws BeansException {
 if (this.logger.isDebugEnabled()) {
  this.logger.debug("Pre-instantiating singletons in " + this);
 }
  //1）、获取容器中的所有Bean，依次进行初始化和创建对象 
 List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames);
 for (String beanName : beanNames) {
  //2）、获取Bean的定义信息；RootBeanDefinition
  RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
  //3）、Bean不是抽象的，是单实例的，不是懒加载；
  if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
   // 3.1）、判断是否是FactoryBean；是否是实现FactoryBean接口的Bean；
   if (isFactoryBean(beanName)) {
    final FactoryBean<?> factory = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName);
    boolean isEagerInit;
    if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
     isEagerInit = AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
      @Override
      public Boolean run() {
       return ((SmartFactoryBean<?>) factory).isEagerInit();
      }
     }, getAccessControlContext());
    }
    else {
     isEagerInit = (factory instanceof SmartFactoryBean &&
         ((SmartFactoryBean<?>) factory).isEagerInit());
    }
    if (isEagerInit) {
     getBean(beanName);
    }
   }
   else { //3.2）、不是工厂Bean。利用getBean(beanName);创建对象
    getBean(beanName); //详情请见 （11.1.3.2 创建bean ->doGetBean）章节
   }
  }
 }
 // 循环所有的bean 
 for (String beanName : beanNames) {
  Object singletonInstance = getSingleton(beanName);
  //判断bean是否实现了SmartInitializingSingleton 接口如果是；就执行afterSingletonsInstantiated()；
  if (singletonInstance instanceof SmartInitializingSingleton) {
   final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
   if (System.getSecurityManager() != null) {
    AccessController.doPrivileged(new PrivilegedAction<Object>() {
     @Override
     public Object run() {
      smartSingleton.afterSingletonsInstantiated();
      return null;
     }
    }, getAccessControlContext());
   }
   else {
    //执行实现类的afterSingletonsInstantiated()；
    smartSingleton.afterSingletonsInstantiated();
   }
  }
 }
}

11.1.3.2 创建bean ->doGetBean

AbstractBeanFactory.doGetBean()方法

5）、将创建的Bean添加到缓存中singletonObjects；ioc容器就是这些Map；很多的Map里面保存了单实例Bean，环境信息。。。。；


protected <T> T doGetBean(
 final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly)
 throws BeansException {
 final String beanName = transformedBeanName(name);
 Object bean;
/**
2、先获取缓存中保存的单实例Bean。如果能获取到说明这个Bean之前被创建过（所有创建过的单实例Bean都会被缓存起来）
从private final Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(256);获取的
 **/
 Object sharedInstance = getSingleton(beanName);
 //如果没有获取到创建bean 
 if (sharedInstance != null && args == null) {
  if (logger.isDebugEnabled()) {
   if (isSingletonCurrentlyInCreation(beanName)) {
    logger.debug("Returning eagerly cached instance of singleton bean '" + beanName +
        "' that is not fully initialized yet - a consequence of a circular reference");
   }
   else {
    logger.debug("Returning cached instance of singleton bean '" + beanName + "'");
   }
  }
  bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
 }
 else {//3、缓存中获取不到，开始Bean的创建对象流程；
  // Fail if we're already creating this bean instance:
  // We're assumably within a circular reference.
  if (isPrototypeCurrentlyInCreation(beanName)) {
   throw new BeanCurrentlyInCreationException(beanName);
  }
  // 获取父beanFatory 检查这个bean是否创建了
  BeanFactory parentBeanFactory = getParentBeanFactory();
  if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
   // Not found -> check parent.
   String nameToLookup = originalBeanName(name);
   if (args != null) {
    return (T) parentBeanFactory.getBean(nameToLookup, args);
   }
   else { 
    return parentBeanFactory.getBean(nameToLookup, requiredType);
   }
  }
  // 4、标记当前bean已经被创建
  if (!typeCheckOnly) {
   markBeanAsCreated(beanName);
  }
  try {
   // 5、获取Bean的定义信息；
   final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
   checkMergedBeanDefinition(mbd, beanName, args);
   // 6、【获取当前Bean依赖的其他Bean;如果有按照getBean()把依赖的Bean先创建出来；】
   String[] dependsOn = mbd.getDependsOn();
   if (dependsOn != null) {
    for (String dep : dependsOn) {
     if (isDependent(beanName, dep)) {
      throw new BeanCreationException(mbd.getResourceDescription(), beanName,
              "Circular depends-on relationship between '" + beanName + "' and '" + dep + "'");
     }
     registerDependentBean(dep, beanName);
     getBean(dep); //先创建依赖的bean
    }
   }
   // 启动单实例的bean的创建流程
   if (mbd.isSingleton()) {
    //获取到单实例bean后，添加到缓存中 singletonObjects（）
  //Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(256);
    sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() {
     @Override
     public Object getObject() throws BeansException {
      try {
       //创建Bean ,见11.1.3.2.6.1
       return createBean(beanName, mbd, args);
      }
      catch (BeansException ex) {
       destroySingleton(beanName);
       throw ex;
      }
     }
    });
    bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
   }
// 下面部分不重要了
   else if (mbd.isPrototype()) {
    // It's a prototype -> create a new instance.
    Object prototypeInstance = null;
    try {
     beforePrototypeCreation(beanName);
     prototypeInstance = createBean(beanName, mbd, args);
    }
    finally {
     afterPrototypeCreation(beanName);
    }
    bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
   }
   else {
    String scopeName = mbd.getScope();
    final Scope scope = this.scopes.get(scopeName);
    if (scope == null) {
     throw new IllegalStateException("No Scope registered for scope name '" + scopeName + "'");
    }
    try {
     Object scopedInstance = scope.get(beanName, new ObjectFactory<Object>() {
      @Override
      public Object getObject() throws BeansException {
       beforePrototypeCreation(beanName);
       try {
        return createBean(beanName, mbd, args);
       }
       finally {
        afterPrototypeCreation(beanName);
       }
      }
     });
     bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
    }
    catch (IllegalStateException ex) {
     throw new BeanCreationException(beanName,
             "Scope '" + scopeName + "' is not active for the current thread; consider " +
             "defining a scoped proxy for this bean if you intend to refer to it from a singleton",
             ex);
    }
   }
  }
  catch (BeansException ex) {
   cleanupAfterBeanCreationFailure(beanName);
   throw ex;
  }
 }
 // Check if required type matches the type of the actual bean instance.
 if (requiredType != null && bean != null && !requiredType.isInstance(bean)) {
  try {
   return getTypeConverter().convertIfNecessary(bean, requiredType);
  }
  catch (TypeMismatchException ex) {
   if (logger.isDebugEnabled()) {
    logger.debug("Failed to convert bean '" + name + "' to required type '" +
        ClassUtils.getQualifiedName(requiredType) + "'", ex);
   }
   throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
  }
 }
 return (T) bean;
}

11.1.3.2.6.1 创建单实例bean

AbstractAutowireCapableBeanFactory.createBean() 这个类中


protected Object createBean(String beanName, RootBeanDefinition mbd, Object[] args) throws BeanCreationException {
 if (logger.isDebugEnabled()) {
  logger.debug("Creating instance of bean '" + beanName + "'");
 }
 RootBeanDefinition mbdToUse = mbd; //bean定义信息
 // 解析bean的类型
 Class<?> resolvedClass = resolveBeanClass(mbd, beanName);
 if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
  mbdToUse = new RootBeanDefinition(mbd);
  mbdToUse.setBeanClass(resolvedClass);
 }
 // Prepare method overrides.
 try {
  mbdToUse.prepareMethodOverrides();
 }
 catch (BeanDefinitionValidationException ex) {
  throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(),
            beanName, "Validation of method overrides failed", ex);
 }
 try {
  //让BeanPostProcessor先拦截返回代理对象；
  /** 判断是否为：InstantiationAwareBeanPostProcessor 的，如果是执行前后置方法
  【InstantiationAwareBeanPostProcessor】：提前执行；
  先触发：postProcessBeforeInstantiation()；
  如果有返回值：再触发postProcessAfterInitialization()；
  **/
  Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
  if (bean != null) { //如果 有对象返回
   return bean;
  }
 }
 catch (Throwable ex) {
  throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName,
          "BeanPostProcessor before instantiation of bean failed", ex);
 }
 // 没有对象 创建一个bean
 Object beanInstance = doCreateBean(beanName, mbdToUse, args);
 if (logger.isDebugEnabled()) {
  logger.debug("Finished creating instance of bean '" + beanName + "'");
 }
 //返回创建的bean 
 return beanInstance;
}

1、doCreateBean()创建一个bean

后置处理器：MergedBeanDefinitionPostProcessor ，bean实例化之后调用


//doCreateBean():508, AbstractAutowireCapableBeanFactory 类中
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)
 throws BeanCreationException {
 // bean的包装
 BeanWrapper instanceWrapper = null;
 if (mbd.isSingleton()) {
  instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
 }
 if (instanceWrapper == null) {
  // 1）、【创建Bean实例】利用工厂方法或者对象的构造器创建出Bean实例；
  instanceWrapper = createBeanInstance(beanName, mbd, args);
 }
 final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
 Class<?> beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);
 mbd.resolvedTargetType = beanType;
 // Allow post-processors to modify the merged bean definition.
 synchronized (mbd.postProcessingLock) {
  if (!mbd.postProcessed) {
   try {
    //调用MergedBeanDefinitionPostProcessor的postProcessMergedBeanDefinition(mbd, beanType, beanName);
    //判断是否为：MergedBeanDefinitionPostProcessor 类型的，如果是，调用方法
    //MergedBeanDefinitionPostProcessor 后置处理器是在bean实例换之后调用的
    applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
   }
   catch (Throwable ex) {
    throw new BeanCreationException(mbd.getResourceDescription(), beanName,
            "Post-processing of merged bean definition failed", ex);
   }
   mbd.postProcessed = true;
  }
 }
 //判断bean 是否为单实例的，如果是单实例的添加到缓存中
 boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
          isSingletonCurrentlyInCreation(beanName));
 if (earlySingletonExposure) {
  if (logger.isDebugEnabled()) {
   logger.debug("Eagerly caching bean '" + beanName +
       "' to allow for resolving potential circular references");
  }
  //添加bean到缓存中
  addSingletonFactory(beanName, new ObjectFactory<Object>() {
   @Override
   public Object getObject() throws BeansException {
    return getEarlyBeanReference(beanName, mbd, bean);
   }
  });
 }
 // Initialize the bean instance.
 Object exposedObject = bean;
 try {
  //为bean 赋值,见1.1部分
  populateBean(beanName, mbd, instanceWrapper);
  if (exposedObject != null) {
   // 4）、【Bean初始化】
   exposedObject = initializeBean(beanName, exposedObject, mbd);
  }
 }
 catch (Throwable ex) {
  if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {
   throw (BeanCreationException) ex;
  }
  else {
   throw new BeanCreationException(
    mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);
  }
 }
 if (earlySingletonExposure) {
  //获取单实例bean,此时已经创建好了
  Object earlySingletonReference = getSingleton(beanName, false);
  if (earlySingletonReference != null) {
   if (exposedObject == bean) {
    exposedObject = earlySingletonReference;
   }
   else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
    String[] dependentBeans = getDependentBeans(beanName);
    Set<String> actualDependentBeans = new LinkedHashSet<String>(dependentBeans.length);
    for (String dependentBean : dependentBeans) {
     if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
      actualDependentBeans.add(dependentBean);
     }
    }
    if (!actualDependentBeans.isEmpty()) {
     throw new BeanCurrentlyInCreationException(beanName,
                "Bean with name '" + beanName + "' has been injected into other beans [" +
                StringUtils.collectionToCommaDelimitedString(actualDependentBeans) +
                "] in its raw version as part of a circular reference, but has eventually been " +
                "wrapped. This means that said other beans do not use the final version of the " +
                "bean. This is often the result of over-eager type matching - consider using " +
                "'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example.");
    }
   }
  }
 }
 // 5）、注册实现了DisposableBean 接口Bean的销毁方法；只是注册没有去执行，容器关闭之后才去调用的
 try {
  registerDisposableBeanIfNecessary(beanName, bean, mbd);
 }
 catch (BeanDefinitionValidationException ex) {
  throw new BeanCreationException(
   mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
 }
 return exposedObject;
}

1.1 populateBean()创建bean后属性赋值


//populateBean():1204, AbstractAutowireCapableBeanFactory 
protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
 PropertyValues pvs = mbd.getPropertyValues();
 if (bw == null) {
  if (!pvs.isEmpty()) {
   throw new BeanCreationException(
    mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
  }
  else {
   // Skip property population phase for null instance.
   return;
  }
 }
 // Give any InstantiationAwareBeanPostProcessors the opportunity to modify the
 // state of the bean before properties are set. This can be used, for example,
 // to support styles of field injection.
 boolean continueWithPropertyPopulation = true;
 //赋值之前：
 /* 1）、拿到InstantiationAwareBeanPostProcessor后置处理器；
  执行处理器的postProcessAfterInstantiation()； 方法*/
 if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
  for (BeanPostProcessor bp : getBeanPostProcessors()) {
   if (bp instanceof InstantiationAwareBeanPostProcessor) {
    InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
    //执行
    if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
     continueWithPropertyPopulation = false;
     break;
    }
   }
  }
 }
 if (!continueWithPropertyPopulation) {
  return;
 }
 if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
  mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
  MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
  // autowire 按name注入
  if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
   autowireByName(beanName, mbd, bw, newPvs);
  }
  // autowire 按类型注入
  if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
   autowireByType(beanName, mbd, bw, newPvs);
  }
  pvs = newPvs;
 }
 boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
 boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
/*2）、拿到InstantiationAwareBeanPostProcessor后置处理器；
 执行 postProcessPropertyValues()； 获取到属性的值，此时还未赋值*/
 if (hasInstAwareBpps || needsDepCheck) {
  PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
  if (hasInstAwareBpps) {
   for (BeanPostProcessor bp : getBeanPostProcessors()) {
    if (bp instanceof InstantiationAwareBeanPostProcessor) {
     InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
     pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
     if (pvs == null) {
      return;
     }
    }
   }
  }
  if (needsDepCheck) {
   checkDependencies(beanName, mbd, filteredPds, pvs);
  }
 }
//=====赋值之前：=== 
//3）、应用Bean属性的值；为属性利用setter方法等进行赋值；
 applyPropertyValues(beanName, mbd, bw, pvs);
}

1.2 、Bean初始化 initializeBean

initializeBean():1605, AbstractAutowireCapableBeanFactory


//初始化
protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
 if (System.getSecurityManager() != null) {
  AccessController.doPrivileged(new PrivilegedAction<Object>() {
   @Override
   public Object run() {
    invokeAwareMethods(beanName, bean);
    return null;
   }
  }, getAccessControlContext());
 }
 else {
  //1）、【执行Aware接口方法】invokeAwareMethods(beanName, bean);执行xxxAware接口的方法
  //判断是否实现了 BeanNameAware\BeanClassLoaderAware\BeanFactoryAware 这些接口的bean，如果是执行相应的方法
  invokeAwareMethods(beanName, bean);
 }
 Object wrappedBean = bean;
 if (mbd == null || !mbd.isSynthetic()) {
  //2）、【执行后置处理器BeanPostProcessor初始化之前】 执行所有的 BeanPostProcessor.postProcessBeforeInitialization（）;
  wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
 }
 try {
  //3）、【执行初始化方法】
  invokeInitMethods(beanName, wrappedBean, mbd);
 }
 catch (Throwable ex) {
  throw new BeanCreationException(
   (mbd != null ? mbd.getResourceDescription() : null),
   beanName, "Invocation of init method failed", ex);
 }
 //4）、【执行后置处理器初始化之后】 执行所有的beanProcessor.postProcessAfterInitialization(result, beanName);方法
 if (mbd == null || !mbd.isSynthetic()) {
  wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
 }
 return wrappedBean;
}

1.2.1 执行bean的初始化方法init

1）、是否是InitializingBean接口的实现；执行接口规定的初始化；

2）、是否自定义初始化方法；通过注解的方式添加了initMethod方法的，

例如： @Bean(initMethod="init",destroyMethod="detory")


//invokeInitMethods():1667, AbstractAutowireCapableBeanFactory 
protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
 throws Throwable {
//1）、是否是InitializingBean接口的实现；执行接口规定的初始化 ,执行afterPropertiesSet()这个方法；
 boolean isInitializingBean = (bean instanceof InitializingBean);
 if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
  if (logger.isDebugEnabled()) {
   logger.debug("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");
  }
  if (System.getSecurityManager() != null) {
   try {
    AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
     @Override
     public Object run() throws Exception {
      ((InitializingBean) bean).afterPropertiesSet();
      return null;
     }
    }, getAccessControlContext());
   }
   catch (PrivilegedActionException pae) {
    throw pae.getException();
   }
  }
  else {
   //执行实现InitializingBean的afterPropertiesSet方法
   ((InitializingBean) bean).afterPropertiesSet();
  }
 }
 if (mbd != null) {
  //执行通过注解自定义的initMethod 方法
  String initMethodName = mbd.getInitMethodName();
  if (initMethodName != null && !(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&
   !mbd.isExternallyManagedInitMethod(initMethodName)) {
   invokeCustomInitMethod(beanName, bean, mbd);
  }
 }
}

12、完成BeanFactory的初始化创建工作；IOC容器就创建完成；刷新


protected void finishRefresh() {
 //1. 初始化生命周期有关的后置处理器，BeanFactory创建完成后刷新相关的工作
 //默认从容器中找是否有lifecycleProcessor的组件【LifecycleProcessor】；如果没有new DefaultLifecycleProcessor();加入到容器；
 initLifecycleProcessor();
 //2. 拿到前面定义的生命周期处理器（LifecycleProcessor）；回调onRefresh()；
 getLifecycleProcessor().onRefresh();
 //3. 发布容器刷新完成事件；
 publishEvent(new ContextRefreshedEvent(this));
 //4.暴露
 LiveBeansView.registerApplicationContext(this);
}

二、Spring 启动流程的总结

1）、Spring容器在启动的时候，先会保存所有注册进来的Bean的定义信息；

1）、xml注册bean；<bean>

2）、注解注册Bean；@Service、@Component、@Bean、xxx

2）、Spring容器会合适的时机创建这些Bean

1）、用到这个bean的时候；利用getBean创建bean；创建好以后保存在容器中；

2）、统一创建剩下所有的bean的时候；finishBeanFactoryInitialization()；

3）、后置处理器；BeanPostProcessor

1）、每一个bean创建完成，都会使用各种后置处理器进行处理；来增强bean的功能；

AutowiredAnnotationBeanPostProcessor:处理自动注入

AnnotationAwareAspectJAutoProxyCreator:来做AOP功能；

xxx....