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源码分析 | Spring IOC容器焦点流程

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深夜敲代码 发表于 2021-8-17 13:08:32 | 显示全部楼层 |阅读模式 打印 上一主题 下一主题
简朴介绍

Spring IOC的焦点方法就在于refresh方法,这个方法内里完成了Spring的初始化、准备bean、实例化bean和扩展功能的实现。

  • 这个方法的作用是什么?
  • 它是如何完成这些功能的?
  • 为什么要如许去实现?
  • 有哪些值得借鉴的地方?
<hr>refresh方法

在ConfigurableApplicationContext内里定义了这个方法:
/** * Load or refresh the persistent representation of the configuration, which * might be from Java-based configuration, an XML file, a properties file, a * relational database schema, or some other format. *
As this is a startup method, it should destroy already created singletons * if it fails, to avoid dangling resources. In other words, after invocation * of this method, either all or no singletons at all should be instantiated. * @throws BeansException if the bean factory could not be initialized * @throws IllegalStateException if already initialized and multiple refresh * attempts are not supported */void refresh() throws BeansException, IllegalStateException;根据注释可以知道,这个方法是用来加载革新设置,这些设置大概来自java设置、xml文件、properties文件、关系型数据库大概其他格式。
作为一个启动方法,它应当在初始化失败后销毁已经创建的单例,防止占着资源而不使用。也就是说调用这个方法的话,要么所有的单例已经被实例化,要么所有的单例都不存在。
BeansException:bean工厂不能被初始化,抛出BeansException
IllegalStateException:bean工厂已经被初始化了,但是不支持多次革新,抛出IllegalStateException
<hr>具体实现

在AbstractApplicationContext中进行了实现:
@Overridepublic void refresh() throws BeansException, IllegalStateException {   synchronized (this.startupShutdownMonitor) {      //为革新做准备,初始化各种状态,启动时间、关闭激活状态、设置文件信息等      prepareRefresh();      //关照子类革新内部BeanFactory,并返回革新后的BeanFactory      //关注方法中的refreshBeanFactory方法,两个子类对它重写的差异      //AbstractRefreshableApplicationContext#refreshBeanFactory中重新构建,完成BeanDefinition的剖析构建      //GenericApplicationContext#refreshBeanFactory则是设置ID,并且只能革新一次      ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();      //给容器准备BeanFactory,设置相关的属性      prepareBeanFactory(beanFactory);      try {         //答应子类处理后置beanFactory         postProcessBeanFactory(beanFactory);         //调用注册了beanFactory后置处理器接口实例bean对应的方法         invokeBeanFactoryPostProcessors(beanFactory);         //注册bean后置处理器接口的实例bean         registerBeanPostProcessors(beanFactory);         //初始化国际化资源         initMessageSource();         //初始化事件流传者         initApplicationEventMulticaster();         //refresh事件,初始化一些指定的bean         onRefresh();         //注册监听器bean         registerListeners();         //完成bean工厂的初始化,初始化所有非懒加载的单例bean         finishBeanFactoryInitialization(beanFactory);         //末了,发布finishRefresh事件         finishRefresh();      }      catch (BeansException ex) {         if (logger.isWarnEnabled()) {            logger.warn("Exception encountered during context initialization - " +                  "cancelling refresh attempt: " + ex);         }         //销毁了所有已经创建了的单例bean         destroyBeans();         //重置active标志         cancelRefresh(ex);         // Propagate exception to caller.         throw ex;      }      finally {         // Reset common introspection caches in Spring&#39;s core, since we         // might not ever need metadata for singleton beans anymore...         resetCommonCaches();      }   }}使用示例:
GenericApplicationContext context3 = new GenericApplicationContext();new XmlBeanDefinitionReader(context3).loadBeanDefinitions("classpath:application.xml");new ClassPathBeanDefinitionScanner(context3).scan("edu.demo");// 一定要革新context3.refresh();<hr>IOC容器革新整体流程

prepareRefresh方法

//关闭和革新的状态都是AtomicBoolean类型的,原子性/** Flag that indicates whether this context is currently active. */private final AtomicBoolean active = new AtomicBoolean();/** Flag that indicates whether this context has been closed already. */private final AtomicBoolean closed = new AtomicBoolean();/** * 为容器革新做准备,设置启动日期和活动标识 * 并实行一些资源的初始化 */protected void prepareRefresh() {   //容器切换到启动状态   //设置启动容器的时间   this.startupDate = System.currentTimeMillis();   //设置关闭的状态   this.closed.set(false);   //设置启动的状态   this.active.set(true);   if (logger.isDebugEnabled()) {      if (logger.isTraceEnabled()) {         logger.trace("Refreshing " + this);      }      else {         logger.debug("Refreshing " + getDisplayName());      }   }   //初始化容器的占位符资源   initPropertySources();   // 验证所有标志为required的属性都是可剖析的:   // see ConfigurablePropertyResolver#setRequiredProperties   getEnvironment().validateRequiredProperties();    //一些监听器的初始化   // Store pre-refresh ApplicationListeners...   if (this.earlyApplicationListeners == null) {      this.earlyApplicationListeners = new LinkedHashSet(this.applicationListeners);   }   else {      // Reset local application listeners to pre-refresh state.      this.applicationListeners.clear();      this.applicationListeners.addAll(this.earlyApplicationListeners);   }   // Allow for the collection of early ApplicationEvents,   // to be published once the multicaster is available...   this.earlyApplicationEvents = new LinkedHashSet();}obtainFreshBeanFactory方法

/** * 告诉子类革新内部的bean factory. * @return the fresh BeanFactory instance * @see #refreshBeanFactory() * @see #getBeanFactory() */protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {   refreshBeanFactory();   return getBeanFactory();}其实就是设置用户的属性、加载bean定义,并且返回革新后的bean工厂。prepareBeanFacotry方法内部又有两个抽象方法构成,交给子类去实现。也就是说子类必定含有一个BeanFactory实例,并且还需要提供革新方法,返回BeanFactory实例的方法。
具体实现类:

  • AbstractRefreshableApplicationContext
AbstractRefreshableApplicationContext中实现的革新方法,可以被多次的调用实行,也就是可以多次革新。
/** * 实际的革新方法。关闭以前的bean工厂,初始化一个新的bean工厂 */@Overrideprotected final void refreshBeanFactory() throws BeansException {   //如果存在bean工厂,则销毁单例bean,关闭bean工厂   if (hasBeanFactory()) {      destroyBeans();      closeBeanFactory();   }   try {      //创建DefaultListableBeanFactory实例      DefaultListableBeanFactory beanFactory = createBeanFactory();      //设置ID      beanFactory.setSerializationId(getId());      //自定义bean工厂属性,bean定义重新、循环引用等设置      customizeBeanFactory(beanFactory);      //等待子类实现的,向bean工厂注册bean定义      loadBeanDefinitions(beanFactory);      //持有bean工厂的实例,以便在getBeanFactory方法中返回出去      this.beanFactory = beanFactory;   }   catch (IOException ex) {      throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);   }}//自定义bean工厂属性protected void customizeBeanFactory(DefaultListableBeanFactory beanFactory) {   if (this.allowBeanDefinitionOverriding != null) {      beanFactory.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);   }   if (this.allowCircularReferences != null) {      beanFactory.setAllowCircularReferences(this.allowCircularReferences);   }}//关闭bean工厂的方法@Overrideprotected final void closeBeanFactory() {   DefaultListableBeanFactory beanFactory = this.beanFactory;   //如果bean工厂存在   if (beanFactory != null) {      //设置ID为空      beanFactory.setSerializationId(null);      //设置bean工厂的实例为空      this.beanFactory = null;   }}AbstractApplicationContext类中的销毁方法:
//销毁方法protected void destroyBeans() {   getBeanFactory().destroySingletons();}

  • GenericApplicationContext
GenericApplicationContext中的革新方法,只能被调用一次,被AtomicBoolean类型的refreshed控制着
private final AtomicBoolean refreshed = new AtomicBoolean();/** * 持有一个内部的bean工厂,通过公共的方法注册bean * @see #registerBeanDefinition */@Overrideprotected final void refreshBeanFactory() throws IllegalStateException {   //CAS的方式进行修改   //多次革新就抛出异常   if (!this.refreshed.compareAndSet(false, true)) {      throw new IllegalStateException(            "GenericApplicationContext does not support multiple refresh attempts: just call &#39;refresh&#39; once");   }   //设置ID   this.beanFactory.setSerializationId(getId());}beanFactory在构造函数中被创建的,代码如下:
/** * Create a new GenericApplicationContext. * @see #registerBeanDefinition * @see #refresh */public GenericApplicationContext() {   this.beanFactory = new DefaultListableBeanFactory();}/** * Create a new GenericApplicationContext with the given DefaultListableBeanFactory. * @param beanFactory the DefaultListableBeanFactory instance to use for this context * @see #registerBeanDefinition * @see #refresh */public GenericApplicationContext(DefaultListableBeanFactory beanFactory) {   Assert.notNull(beanFactory, "BeanFactory must not be null");   this.beanFactory = beanFactory;}这个时候的beanFactory内里都有些什么呢?根据之前的注解的加载过程。可以知道,应该有BeanFactoryPostProcessor、BeanPostProcessor、ApplicationListener信息。
prepareBeanFactory方法

/** * 设置工厂的标准容器特征 * 比方容器的ClassLoader和post-processor * @param beanFactory the BeanFactory to configure */protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {   // Tell the internal bean factory to use the context&#39;s class loader etc.   //给bean工作准备ClassLoader、SPL表达式剖析器、属性编辑注册器等   beanFactory.setBeanClassLoader(getClassLoader());   beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));   beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));   // Configure the bean factory with context callbacks.   //向beanFactory注册ApplicationContextAwareProcessor   //背面的六种Aware忽略他们的自动依靠注入   beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));   beanFactory.ignoreDependencyInterface(EnvironmentAware.class);   beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);   beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);   beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);   beanFactory.ignoreDependencyInterface(MessageSourceAware.class);   beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);   // BeanFactory interface not registered as resolvable type in a plain factory.   // MessageSource registered (and found for autowiring) as a bean.   //依靠需要使用的bean,IOC容器自己的多脚色身份,@Autowried方式获得下列类型bean   beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);   beanFactory.registerResolvableDependency(ResourceLoader.class, this);   beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);   beanFactory.registerResolvableDependency(ApplicationContext.class, this);   // Register early post-processor for detecting inner beans as ApplicationListeners.   //注入ApplicationListeners接口实现的发现处理器,同时带有销毁、bean定义混合的实现   beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));   // Detect a LoadTimeWeaver and prepare for weaving, if found.   if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {      beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));      // Set a temporary ClassLoader for type matching.      beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));   }   // Register default environment beans.   if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {      beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());   }   if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {      // properties设置文件      beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());   }   if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {      // 操作系统情况变量:JAVA_HOME等      beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());   }}ApplicationContextAwareProcessor方法中的,注入Processor
@Override@Nullablepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {//只针对EnvironmentAware、EmbeddedValueResolverAware、ResourceLoaderAware、ApplicationEventPublisherAware、MessageSourceAware、ApplicationContextAware 6种实现进行处理。   if (!(bean instanceof EnvironmentAware || bean instanceof EmbeddedValueResolverAware ||         bean instanceof ResourceLoaderAware || bean instanceof ApplicationEventPublisherAware ||         bean instanceof MessageSourceAware || bean instanceof ApplicationContextAware)){      return bean;   }   AccessControlContext acc = null;   if (System.getSecurityManager() != null) {      acc = this.applicationContext.getBeanFactory().getAccessControlContext();   }   if (acc != null) {      AccessController.doPrivileged((PrivilegedAction) () -> {         invokeAwareInterfaces(bean);         return null;      }, acc);   }   else {      invokeAwareInterfaces(bean);   }   return bean;}//将beanFactory注入给上述的6种Awareprivate void invokeAwareInterfaces(Object bean) {   if (bean instanceof EnvironmentAware) {      ((EnvironmentAware) bean).setEnvironment(this.applicationContext.getEnvironment());   }   if (bean instanceof EmbeddedValueResolverAware) {      ((EmbeddedValueResolverAware) bean).setEmbeddedValueResolver(this.embeddedValueResolver);   }   if (bean instanceof ResourceLoaderAware) {      ((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);   }   if (bean instanceof ApplicationEventPublisherAware) {      ((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext);   }   if (bean instanceof MessageSourceAware) {      ((MessageSourceAware) bean).setMessageSource(this.applicationContext);   }   if (bean instanceof ApplicationContextAware) {      ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);   }}postProcessBeanFactory方法

postProcessBeanFactory方法并没有去实现它。
/** * Modify the application context&#39;s internal bean factory after its standard * initialization. All bean definitions will have been loaded, but no beans * will have been instantiated yet. This allows for registering special * BeanPostProcessors etc in certain ApplicationContext implementations. * @param beanFactory the bean factory used by the application context */protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {}invokeBeanFactoryPostProcessors方法

这个时候,bean工厂基本上已经准备完成,但是bean实例还没有进行初始化,接下来调用BeanFactoryPostProcessor对Bean工厂中的Bean定义进行调整
/** * 实行BeanFactoryPostProcessor *
必须在单例bean实例化之前调用 */protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {   //最重要的处理在委托内里实现   //getBeanFactoryPostProcessors()获取的是容器内里的列表属性,   //这个属性没有机会给外部去注入BeanFactoryPostProcessor对象。   //因为ApplicationContext子类在构造函数中调用了refresh方法。以是这里是个空值   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()));   }}invokeBeanFactoryPostProcessors方法:
public static void invokeBeanFactoryPostProcessors(      ConfigurableListableBeanFactory beanFactory, List beanFactoryPostProcessors) {   // Invoke BeanDefinitionRegistryPostProcessors first, if any.   Set processedBeans = new HashSet();   if (beanFactory instanceof BeanDefinitionRegistry) {      BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;      //BeanFactoryPostProcessor和BeanDefinitionRegistryPostProcessor      List regularPostProcessors = new ArrayList();      List registryProcessors = new ArrayList();      for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {         if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {            //获取BeanDefinitionRegistryPostProcessor            BeanDefinitionRegistryPostProcessor registryProcessor =                  (BeanDefinitionRegistryPostProcessor) postProcessor;            //这里既然做了处理,为何又加入到了registryProcessors聚集中?               registryProcessor.postProcessBeanDefinitionRegistry(registry);            registryProcessors.add(registryProcessor);         }         else {            regularPostProcessors.add(postProcessor);         }      }      // Do not initialize FactoryBeans here: We need to leave all regular beans      // uninitialized to let the bean factory post-processors apply to them!      // Separate between BeanDefinitionRegistryPostProcessors that implement      // PriorityOrdered, Ordered, and the rest.      List currentRegistryProcessors = new ArrayList();      // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.      //第一步,处理继承PriorityOrdered的BeanDefinitionRegistryPostProcessors      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);         }      }      sortPostProcessors(currentRegistryProcessors, beanFactory);      registryProcessors.addAll(currentRegistryProcessors);      invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);      currentRegistryProcessors.clear();      // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.      //第二步,处理继承自Ordered的BeanDefinitionRegistryPostProcessors      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.      //末了一步,处理没有优先次序的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.      //回调      invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);      invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);   }   else {      // Invoke factory processors registered with the context instance.      invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);   }   // Do not initialize FactoryBeans here: We need to leave all regular beans   // uninitialized to let the bean factory post-processors apply to them!   String[] postProcessorNames =         beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);   // Separate between BeanFactoryPostProcessors that implement PriorityOrdered,   // Ordered, and the rest.   //处理BeanFactoryPostProcessor,按照PriorityOrdered、Ordered和其他   List priorityOrderedPostProcessors = new ArrayList();   List orderedPostProcessorNames = new ArrayList();   List nonOrderedPostProcessorNames = new ArrayList();   for (String ppName : postProcessorNames) {      if (processedBeans.contains(ppName)) {         // skip - already processed in first phase above      }      else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {         priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));      }      else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {         orderedPostProcessorNames.add(ppName);      }      else {         nonOrderedPostProcessorNames.add(ppName);      }   }   // First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.   //第一步,处理继承自PriorityOrdered的BeanFactoryPostProcessors   sortPostProcessors(priorityOrderedPostProcessors, beanFactory);   invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);   // Next, invoke the BeanFactoryPostProcessors that implement Ordered.   //第二步,处理继承自Ordered的BeanFactoryPostProcessors   List orderedPostProcessors = new ArrayList(orderedPostProcessorNames.size());   for (String postProcessorName : orderedPostProcessorNames) {      orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));   }   sortPostProcessors(orderedPostProcessors, beanFactory);   invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);   // Finally, invoke all other BeanFactoryPostProcessors.   //末了一步,处理其他的BeanFactoryPostProcessors   List nonOrderedPostProcessors = new ArrayList(nonOrderedPostProcessorNames.size());   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,因为背面的处理器大概会修改元数据   beanFactory.clearMetadataCache();}从上面的源码部分可以看到:

  • 拆成了两部分:registryProcessors、regularPostProcessors,分别处理BeanDefinitionRegistryPostProcessor和BeanFactoryPostProcessor
  • 排序处理:PriorityOrdered、Ordered和为排序的,按照如许的优先级进行处理
多次调用了invokeBeanFactoryPostProcessors,因为在调用BeanFactoryPostProcessors的过程中,还会继续产生BeanFactoryPostProcessors,这里多次调用,就是为了处理掉所有的BeanFactoryPostProcessors。
registerBeanPostProcessors方法

到了这一步,bean定义已经加载完成,bean工厂完成了革新和实例化,而且通过BeanFactoryProcessor修整了bean定义信息,接下来注册BeanPostProcessors
/** * Instantiate and register all BeanPostProcessor beans, * respecting explicit order if given. *
Must be called before any instantiation of application beans. */protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {   PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);}PostProcessorRegistrationDelegate的registerBeanPostProcessors方法:
public static void registerBeanPostProcessors(      ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {   String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);   // Register BeanPostProcessorChecker that logs an info message when   // a bean is created during BeanPostProcessor instantiation, i.e. when   // a bean is not eligible for getting processed by all BeanPostProcessors.   int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;   beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));   // Separate between BeanPostProcessors that implement PriorityOrdered,   // Ordered, and the rest.   List priorityOrderedPostProcessors = new ArrayList();   List internalPostProcessors = new ArrayList();   List orderedPostProcessorNames = new ArrayList();   List nonOrderedPostProcessorNames = new ArrayList();   for (String ppName : postProcessorNames) {      if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {         BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);         priorityOrderedPostProcessors.add(pp);         if (pp instanceof MergedBeanDefinitionPostProcessor) {            internalPostProcessors.add(pp);         }      }      else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {         orderedPostProcessorNames.add(ppName);      }      else {         nonOrderedPostProcessorNames.add(ppName);      }   }   // First, register the BeanPostProcessors that implement PriorityOrdered.   sortPostProcessors(priorityOrderedPostProcessors, beanFactory);   registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);   // Next, register the BeanPostProcessors that implement Ordered.   List orderedPostProcessors = new ArrayList(orderedPostProcessorNames.size());   for (String ppName : orderedPostProcessorNames) {      BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);      orderedPostProcessors.add(pp);      if (pp instanceof MergedBeanDefinitionPostProcessor) {         internalPostProcessors.add(pp);      }   }   sortPostProcessors(orderedPostProcessors, beanFactory);   registerBeanPostProcessors(beanFactory, orderedPostProcessors);   // Now, register all regular BeanPostProcessors.   List nonOrderedPostProcessors = new ArrayList(nonOrderedPostProcessorNames.size());   for (String ppName : nonOrderedPostProcessorNames) {      BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);      nonOrderedPostProcessors.add(pp);      if (pp instanceof MergedBeanDefinitionPostProcessor) {         internalPostProcessors.add(pp);      }   }   registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);   // Finally, re-register all internal BeanPostProcessors.   sortPostProcessors(internalPostProcessors, beanFactory);   registerBeanPostProcessors(beanFactory, internalPostProcessors);   // Re-register post-processor for detecting inner beans as ApplicationListeners,   // moving it to the end of the processor chain (for picking up proxies etc).   beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));}可以看到上面的源码部分,和与BeanFactroyPostProcessor的处理简直一样,排序然后调用处理逻辑。

  • priorityOrderedPostProcessors
  • orderedPostProcessors
  • nonOrderedPostProcessors
  • internalPostProcessors
  • ApplicationListenerDetector
下面是排序的实例:

  • 没有继承任何排序的接口:
@Componentpublic class MyBeanDefinitonRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor {   @Override   public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {      System.out.println("--- MyBeanDefinitonRegistryPostProcessor.postProcessBeanFactory 被实行了。");   }   @Override   public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {      System.out.println("--- MyBeanDefinitonRegistryPostProcessor.postProcessBeanDefinitionRegistry 被实行了。");   }}

  • 继承Ordered接口:
@Componentpublic class MyBeanDefinitonRegistryPostProcessor2 implements BeanDefinitionRegistryPostProcessor, Ordered {   @Override   public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {      System.out.println("--- MyBeanDefinitonRegistryPostProcessor2.postProcessBeanFactory 被实行了。");   }   @Override   public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {      System.out.println("--- MyBeanDefinitonRegistryPostProcessor2.postProcessBeanDefinitionRegistry 被实行了。");   }   @Override   public int getOrder() {      return 0;   }}

  • 继承PriorityOrdered接口:
@Componentpublic class MyBeanDefinitonRegistryPostProcessor3 implements BeanDefinitionRegistryPostProcessor, PriorityOrdered {   @Override   public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {      System.out.println("--- MyBeanDefinitonRegistryPostProcessor3.postProcessBeanFactory 被实行了。");   }   @Override   public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {      System.out.println("--- MyBeanDefinitonRegistryPostProcessor3.postProcessBeanDefinitionRegistry 被实行了。");   }   @Override   public int getOrder() {      return 1;   }}实行结果如下:

                               
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从上图可以清晰的看到,PriorityOrdered > Ordered > 未排序
initMessageSource方法

此时BenPostProcessor都已经注册完成,下一步就是准备国际化资源:
/** * 初始化国际化资源,如果没有,就使用父类的 */protected void initMessageSource() {   //获取bean工厂   ConfigurableListableBeanFactory beanFactory = getBeanFactory();   //如果Bean工厂中存在名为messageSource的bean,则使用它   if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {      this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);      // Make MessageSource aware of parent MessageSource.      //获取父类的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.isTraceEnabled()) {         logger.trace("Using MessageSource [" + this.messageSource + "]");      }   }   else {      // Use empty MessageSource to be able to accept getMessage calls.      //使用DelegatingMessageSource作为国际化资源处理bean      DelegatingMessageSource dms = new DelegatingMessageSource();      dms.setParentMessageSource(getInternalParentMessageSource());      this.messageSource = dms;      beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);      if (logger.isTraceEnabled()) {         logger.trace("No &#39;" + MESSAGE_SOURCE_BEAN_NAME + "&#39; bean, using [" + this.messageSource + "]");      }   }}简朴的例子: 在application.properties设置如下信息:
logging.config=classpath:logback.xmlmy.love=java@Configuration@PropertySource("classpath:/application.properties")public class MessageConfiguration {   @Bean("messageSource")   public ReloadableResourceBundleMessageSource getReloadableResourceBundleMessageSource() {      ReloadableResourceBundleMessageSource rms = new ReloadableResourceBundleMessageSource();      rms.setBasename("message");      return rms;   }}@MyComponetAnnopublic class MessageBean {   @Autowired   private ApplicationContext applicationContext;   public MessageBean() {      System.out.println("-----------------Abean 被实例化了。。。。。。。。。");   }   public void doSomething() {      System.out.println(this + " do something .....my.love="            + this.applicationContext.getEnvironment().getProperty("my.love"));      System.out            .println("-----------project.name=" +                   this.applicationContext.getMessage("project.name", null, Locale.CHINA));   }}public class MessageStarter {   public static void main(String[] args) {      // 注解方式,指定扫描的包      AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(            "edu.demo.spring.message");      MessageBean bean = context.getBean(MessageBean.class);      bean.doSomething();      context.close();   }}输出如下:

                               
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initApplicationEventMulticaster方法

下面就是初始化事件多播器:
/** * 初始化ApplicationEventMulticaster. * Uses SimpleApplicationEventMulticaster if none defined in the context. * @see org.springframework.context.event.SimpleApplicationEventMulticaster */protected void initApplicationEventMulticaster() {   //获取bean工厂   ConfigurableListableBeanFactory beanFactory = getBeanFactory();   //如果bean工厂中包含applicationEventMulticaster,就使用它   if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {      this.applicationEventMulticaster =            beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);      if (logger.isTraceEnabled()) {         logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");      }   }   else {      //使用SimpleApplicationEventMulticaster      this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);      beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);      if (logger.isTraceEnabled()) {         logger.trace("No &#39;" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "&#39; bean, using " +               "[" + this.applicationEventMulticaster.getClass().getSimpleName() + "]");      }   }}onRefresh方法

没有子类进行实现
/** * Template method which can be overridden to add context-specific refresh work. * Called on initialization of special beans, before instantiation of singletons. *
This implementation is empty. * @throws BeansException in case of errors * @see #refresh() */protected void onRefresh() throws BeansException {   // For subclasses: do nothing by default.}registerListeners方法

接下来,查抄事件监听器,并注册到事件流传器上
/** *  在不生成Bean对象的情况下添加ApplicationListener bean作为监听器 * Add beans that implement ApplicationListener as listeners. * Doesn&#39;t affect other listeners, which can be added without being beans. */protected void registerListeners() {   // Register statically specified listeners first.   for (ApplicationListener listener : getApplicationListeners()) {      getApplicationEventMulticaster().addApplicationListener(listener);   }   // Do not initialize FactoryBeans here: We need to leave all regular beans   // uninitialized to let post-processors apply to them!   String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);   for (String listenerBeanName : listenerBeanNames) {      getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);   }   // Publish early application events now that we finally have a multicaster...   Set earlyEventsToProcess = this.earlyApplicationEvents;   this.earlyApplicationEvents = null;   if (!CollectionUtils.isEmpty(earlyEventsToProcess)) {      for (ApplicationEvent earlyEvent : earlyEventsToProcess) {         getApplicationEventMulticaster().multicastEvent(earlyEvent);      }   }}事件广播器实行的方法: SimpleApplicationEventMulticaster的multicastEvent(ApplicationEvent, ResolvableType)方法:
@Overridepublic void multicastEvent(ApplicationEvent event) {   multicastEvent(event, resolveDefaultEventType(event));}@Overridepublic void multicastEvent(final ApplicationEvent event, @Nullable ResolvableType eventType) {   ResolvableType type = (eventType != null ? eventType : resolveDefaultEventType(event));   Executor executor = getTaskExecutor();   for (ApplicationListener listener : getApplicationListeners(event, type)) {      if (executor != null) {         executor.execute(() -> invokeListener(listener, event));      }      else {         invokeListener(listener, event);      }   }}finishBeanFactoryInitialization方法

完成bean工厂的初始化,将bean工厂中,非懒加载的单例bean进行实例化
这一部分将在背面的文章中进行分析
/** * Finish the initialization of this context&#39;s bean factory, * initializing all remaining singleton beans. */protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {   // Initialize conversion service for this context.   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.   if (!beanFactory.hasEmbeddedValueResolver()) {      beanFactory.addEmbeddedValueResolver(strVal -> 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();   // Instantiate all remaining (non-lazy-init) singletons.   beanFactory.preInstantiateSingletons();}finishRefresh方法

/** * Finish the refresh of this context, invoking the LifecycleProcessor&#39;s * onRefresh() method and publishing the * {@link org.springframework.context.event.ContextRefreshedEvent}. */protected void finishRefresh() {   // Clear context-level resource caches (such as ASM metadata from scanning).   //清除缓存   clearResourceCaches();   // Initialize lifecycle processor for this context.   //初始化容器的生命周期处理器   initLifecycleProcessor();   // Propagate refresh to lifecycle processor first.   //将革新流传到生命周期处理器   getLifecycleProcessor().onRefresh();   // Publish the final event.   //发布终极事件   publishEvent(new ContextRefreshedEvent(this));   // Participate in LiveBeansView MBean, if active.   LiveBeansView.registerApplicationContext(this);}容器的关闭 AbstractApplicationContext#close
AbstractApplicationContext#registerShutdownHook
AbstractApplicationContext#doClose
整体流程图如下:

                               
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