从源码开始探究spring容器的创建原理，下面是源码总步骤

@Override
public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {// Prepare this context for refreshing.prepareRefresh();// Tell the subclass to refresh the internal bean factory.ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();// Prepare the bean factory for use in this context.prepareBeanFactory(beanFactory);try {// Allows post-processing of the bean factory in context subclasses.postProcessBeanFactory(beanFactory);// Invoke factory processors registered as beans in the context.invokeBeanFactoryPostProcessors(beanFactory);// Register bean processors that intercept bean creation.registerBeanPostProcessors(beanFactory);// Initialize message source for this context.initMessageSource();// Initialize event multicaster for this context.initApplicationEventMulticaster();// Initialize other special beans in specific context subclasses.onRefresh();// Check for listener beans and register them.registerListeners();// Instantiate all remaining (non-lazy-init) singletons.finishBeanFactoryInitialization(beanFactory);// Last step: publish corresponding event.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();}}
}

一、spring容器的refresh()

 一、prepareRefresh()刷新前的预处理;

@Override
protected void prepareRefresh() {this.scanner.clearCache();super.prepareRefresh();
}
之后会进入AnnotationConfigReactiveWebServerApplicationContext的方法进行缓存的清空
然后会进入下面方法

protected void prepareRefresh() {// Switch to active.
// 记录当前时间以及设置容器关闭以及激活状态this.startupDate = System.currentTimeMillis();this.closed.set(false);this.active.set(true);if (logger.isDebugEnabled()) {if (logger.isTraceEnabled()) {logger.trace("Refreshing " + this);}else {logger.debug("Refreshing " + getDisplayName());}}// Initialize any placeholder property sources in the context environment.// 初始化一些属性设置;子类自定义个性化的属性设置方法；可以用于自己定义initPropertySources();// Validate that all properties marked as required are resolvable:// see ConfigurablePropertyResolver#setRequiredProperties // 检验属性的合法等getEnvironment().validateRequiredProperties();// Store pre-refresh ApplicationListeners...// 保存容器中的一些早期的事件；到时可以使用时间派发器派发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<>();
}

总结：

    1、initPropertySources()初始化一些属性设置;子类自定义个性化的属性设置方法；
    2、getEnvironment().validateRequiredProperties();检验属性的合法等
    3、earlyApplicationEvents= new LinkedHashSet<ApplicationEvent>();保存容器中的一些早期的事件； 

二、obtainFreshBeanFactory()：获取BeanFactory

其实从方法名字就可以看出，这个方法就是用于刷新和获取bean工厂的
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {// 刷新bean工厂refreshBeanFactory();// 获取bean工厂return getBeanFactory();
}

 一、refreshBeanFactory：刷新bean工厂

这个方法主要就是创建了一个this.beanFactory = new DefaultListableBeanFactory();
设置id；

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

这里的beanFactory就是在创建GenericApplicationContext的时候创建了一个DefaultListableBeanFactory 的对象并赋给成员变量beanFactory

private final DefaultListableBeanFactory beanFactory;

二、getBeanFactory();返回刚才GenericApplicationContext创建的BeanFactory对象；

@Override
public final ConfigurableListableBeanFactory getBeanFactory() {return this.beanFactory;
}
这一块没有什么好说的

三、prepareBeanFactory(beanFactory)：BeanFactory的预准备工作

主要就是对BeanFactory进行一些属性设置

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {// Tell the internal bean factory to use the context's class loader etc.
// 设置BeanFactory的类加载器、支持表达式解析器...beanFactory.setBeanClassLoader(getClassLoader());beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));// Configure the bean factory with context callbacks.//添加部分BeanPostProcessor【ApplicationContextAwareProcessor】后置处理器beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
​​​​​​​
// 设置忽略的自动装配的接口EnvironmentAware、EmbeddedValueResolverAware、也就是这些接口的实现类不能通过接口进行自动注入，需要手动注入beanFactory.ignoreDependencyInterface(EnvironmentAware.class);beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);beanFactory.ignoreDependencyInterface(MessageSourceAware.class);beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);// BeanFactory interface not registered as resolvable type in a plain factory.// MessageSource registered (and found for autowiring) as a bean.// 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，也就是使用@Autowired可以注入当前类进行使用   beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);beanFactory.registerResolvableDependency(ResourceLoader.class, this);beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);beanFactory.registerResolvableDependency(ApplicationContext.class, this);// Register early post-processor for detecting inner beans as ApplicationListeners.// 添加BeanPostProcessor后置处理器ApplicationListenerDetectorbeanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));// Detect a LoadTimeWeaver and prepare for weaving, if found.// 添加编译时的AspectJ组件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.//给BeanFactory中注册一些能用的组件if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());}if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());}if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());}
}

总结：

    1、设置BeanFactory的类加载器、支持表达式解析器...
    2、添加部分BeanPostProcessor【ApplicationContextAwareProcessor】
    3、设置忽略的自动装配的接口EnvironmentAware、EmbeddedValueResolverAware、xxx；
    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
    5、添加BeanPostProcessor【ApplicationListenerDetector】
    6、添加编译时的AspectJ；
    7、给BeanFactory中注册一些能用的组件；
        environment【ConfigurableEnvironment类型】、
        systemProperties【Map<String, Object>类型】、
        systemEnvironment【Map<String, Object>类型】

到这一步就相当于bean工厂已经创建完了，该设置的属性也设置完了

四、postProcessBeanFactory(beanFactory)

BeanFactory准备工作完成后进行的后置处理工作，到这里BeanFactory的创建及预准备工作就完成了

 进入这个方法可以看到，这是一个抽象类AbstractApplicationContext的一个空方法。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

 五、invokeBeanFactoryPostProcessors(beanFactory);

BeanFactory创建完成后，就开始利用bean工厂创建各个组件了。invokeBeanFactoryPostProcessors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；这个接口有两大接口：

BeanFactoryPostProcessor、BeanDefinitionRegistryPostProcessor

一、invokeBeanFactoryPostProcessors

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

 二、invokeBeanFactoryPostProcessors方法源码

// 参数beanFactoryPostProcessors是执行 getBeanFactoryPostProcessors()获取到的
public static void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {// Invoke BeanDefinitionRegistryPostProcessors first, if any.Set<String> processedBeans = new HashSet<>();// 判断beanFactory是否是BeanDefinitionRegistry，前面有创建一个DefaultListableBeanFactory 对象，这个是BeanDefinitionRegistry类型if (beanFactory instanceof BeanDefinitionRegistry) {BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();// 获取所有的BeanDefinitionRegistryPostProcessor的数据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<>();// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.String[] postProcessorNames =beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);// 先执行实现了PriorityOrdered优先级接口BeanDefinitionRegistryPostProcessor的// postProcessor.postProcessBeanDefinitionRegistry(registry)方法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);// 在这里执行的invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);currentRegistryProcessors.clear();// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.// 再执行实现了Ordered顺序接口的BeanDefinitionRegistryPostProcessorpostProcessorNames = 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);// 是在这里执行的postProcessor.postProcessBeanDefinitionRegistry(registry)invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);currentRegistryProcessors.clear();// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 最后执行没有实现任何优先级或者是顺序接口的BeanDefinitionRegistryPostProcessorsboolean 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.// 在这里执行的postProcessor.postProcessBeanDefinitionRegistry(registry)invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);}else {// Invoke factory processors registered with the context instance.invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);}// 以上是先执行BeanDefinitionRegistryPostProcessor类相关的操作，以下是执行BeanFactoryPostProcessor相关类的操作// Do not initialize FactoryBeans here: We need to leave all regular beans// uninitialized to let the bean factory post-processors apply to them!
// 通过beanFactory工厂按照类型BeanFactoryPostProcessor获取所有这个类型的bean名字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) {if (processedBeans.contains(ppName)) {// skip - already processed in first phase above}
// 如果实现了PriorityOrdered，优先执行，其次是Ordered，最后是所有，和上面一样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.sortPostProcessors(priorityOrderedPostProcessors, beanFactory);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);invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);// Finally, invoke all other BeanFactoryPostProcessors.List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>();for (String postProcessorName : nonOrderedPostProcessorNames) {nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));}invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);// Clear cached merged bean definitions since the post-processors might have// modified the original metadata, e.g. replacing placeholders in values...beanFactory.clearMetadataCache();}

 三、invokeBeanFactoryPostProcessors方法，执行postProcessBeanFactory

	private static void invokeBeanFactoryPostProcessors(Collection<? extends BeanFactoryPostProcessor> postProcessors, ConfigurableListableBeanFactory beanFactory) {for (BeanFactoryPostProcessor postProcessor : postProcessors) {postProcessor.postProcessBeanFactory(beanFactory);}}

总结： 

BeanFactoryPostProcessor：BeanFactory的后置处理器。在BeanFactory标准初始化之后执行的；
两个接口：BeanFactoryPostProcessor、BeanDefinitionRegistryPostProcessor
1、执行BeanFactoryPostProcessor的方法前先执行BeanDefinitionRegistryPostProcessor
        1）、获取所有的BeanDefinitionRegistryPostProcessor；
        2）、看先执行实现了PriorityOrdered优先级接口的BeanDefinitionRegistryPostProcessor、
            postProcessor.postProcessBeanDefinitionRegistry(registry)
        3）、在执行实现了Ordered顺序接口的BeanDefinitionRegistryPostProcessor；
            postProcessor.postProcessBeanDefinitionRegistry(registry)
        4）、最后执行没有实现任何优先级或者是顺序接口的BeanDefinitionRegistryPostProcessors；
            postProcessor.postProcessBeanDefinitionRegistry(registry)
            
        
2、再执行BeanFactoryPostProcessor的方法
        1）、获取所有的BeanFactoryPostProcessor
        2）、看先执行实现了PriorityOrdered优先级接口的BeanFactoryPostProcessor、
            postProcessor.postProcessBeanFactory()
        3）、在执行实现了Ordered顺序接口的BeanFactoryPostProcessor；
            postProcessor.postProcessBeanFactory()
        4）、最后执行没有实现任何优先级或者是顺序接口的BeanFactoryPostProcessor；
            postProcessor.postProcessBeanFactory()

六、registerBeanPostProcessors(beanFactory);

注册BeanPostProcessor（Bean的后置处理器），上面的是BeanFactoryPostProcessor和BeanDefinitionRegistryPostProcessor（继承至BeanFactoryPostProcessor），先是bean工厂后置处理器执行，然后才会有bean后置处理器执行。

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

1、BeanPostProcessor：下面接口都是继承他
 2、DestructionAwareBeanPostProcessor：执行bean销毁方法的后置处理器
 3、InstantiationAwareBeanPostProcessor：

 （1） 实例化---调用构造函数创建bean：InstantiationAwareBeanPostProcessor在bean的实例化前后执行

  （2）初始化---调用set方法，给属性赋值

4、SmartInstantiationAwareBeanPostProcessor：继承了InstantiationAwareBeanPostProcessor，调用时机一致
5、MergedBeanDefinitionPostProcessor

   （1）、快速获取bean的所有指定信息。
   （2）清理缓存中bean的指定信息。

   （3）bean生命周期中创建实例化对象后，赋值方法前执行

一、registerBeanPostProcessors

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

 二、PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);

public static void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {// 通过bean工厂按BeanPostProcessor类型获取所有符合条件的bean名字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<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();List<String> orderedPostProcessorNames = new ArrayList<>();List<String> nonOrderedPostProcessorNames = new ArrayList<>();// 后置处理器都默认可以通过PriorityOrdered、Ordered接口来执行优先级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);//先注册PriorityOrdered优先级接口的BeanPostProcessor；把每一个BeanPostProcessor；添加到BeanFactory中registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);// Next, register the BeanPostProcessors that implement Ordered.List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();for (String ppName : orderedPostProcessorNames) {BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);orderedPostProcessors.add(pp);if (pp instanceof MergedBeanDefinitionPostProcessor) {internalPostProcessors.add(pp);}}sortPostProcessors(orderedPostProcessors, beanFactory);// 再注册Ordered接口的registerBeanPostProcessors(beanFactory, orderedPostProcessors);// Now, register all regular BeanPostProcessors.List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();for (String ppName : nonOrderedPostProcessorNames) {BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);nonOrderedPostProcessors.add(pp);if (pp instanceof MergedBeanDefinitionPostProcessor) {internalPostProcessors.add(pp);}}// 最后注册没有实现任何优先级接口的registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);// 最终注册MergedBeanDefinitionPostProcessor；internalPostProcessors集合里面的就是MergedBeanDefinitionPostProcessor数据// Finally, re-register all internal BeanPostProcessors.sortPostProcessors(internalPostProcessors, beanFactory);registerBeanPostProcessors(beanFactory, internalPostProcessors);// 注册一个ApplicationListenerDetector；来在Bean创建完成后检查是否是监听器，如果是添加进行容器中// 这里的逻辑是在ApplicationListenerDetector对象创建之后会调用ApplicationListenerDetector对象里面的postProcessAfterInitialization执行的// 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));}

总结： 

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
 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);
3、再注册Ordered接口的
4、最后注册没有实现任何优先级接口的
5、最终注册MergedBeanDefinitionPostProcessor；
6、注册一个ApplicationListenerDetector；来在Bean创建完成后检查是否是ApplicationListener，如果是新增事件监听器applicationContext.addApplicationListener((ApplicationListener<?>) bean);

七、initMessageSource();

初始化MessageSource组件，主要是做国际化功能；消息绑定，消息解析

protected void initMessageSource() {// 获取容器工厂BeanFactoryConfigurableListableBeanFactory beanFactory = getBeanFactory();// 看容器中是否有id为messageSource的，类型是MessageSource的组件,如果有赋值给messageSourceif (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {// MessageSource：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；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.isTraceEnabled()) {logger.trace("Using MessageSource [" + this.messageSource + "]");}}// 如果没有自己创建一个DelegatingMessageSourceelse {// Use empty MessageSource to be able to accept getMessage calls.DelegatingMessageSource dms = new DelegatingMessageSource();dms.setParentMessageSource(getInternalParentMessageSource());this.messageSource = dms;// 把创建好的MessageSource注册在容器中，以后获取国际化配置文件的值的时候，可以自动注入MessageSourcebeanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);if (logger.isTraceEnabled()) {logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");}}}

总结：

1、获取BeanFactory
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：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；
3、把创建好的MessageSource注册在容器中，以后获取国际化配置文件的值的时候，可以自动注入MessageSource；
 beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME,this.messageSource);    

八、initApplicationEventMulticaster();

初始化事件派发器，具体之前文章有记录，可查阅。

	protected void initApplicationEventMulticaster() {ConfigurableListableBeanFactory beanFactory = getBeanFactory();if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {this.applicationEventMulticaster =beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);if (logger.isTraceEnabled()) {logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");}}else {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() + "]");}}}

总结： 

1、获取BeanFactory
2、从BeanFactory中获取applicationEventMulticaster的ApplicationEventMulticaster；
3、如果上一步没有配置；创建一个SimpleApplicationEventMulticaster
4、将创建的ApplicationEventMulticaster添加到BeanFactory中，以后其他组件直接自动注入

九、onRefresh();

主要是留给子容器（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

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

十、registerListeners();

主要是给容器中将所有项目里面的ApplicationListener注册进来

	protected void registerListeners() {// Register statically specified listeners first.// 拿到之前的监听器，填加到事件派发其中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!// 从容器中拿到所有的ApplicationListenerString[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);for (String listenerBeanName : listenerBeanNames) {// 将每个监听器添加到事件派发器中；getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);}// Publish early application events now that we finally have a multicaster...Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;this.earlyApplicationEvents = null;if (earlyEventsToProcess != null) {// 派发之前步骤产生的事件for (ApplicationEvent earlyEvent : earlyEventsToProcess) {getApplicationEventMulticaster().multicastEvent(earlyEvent);}}}

 总结：

1、从容器中拿到所有的ApplicationListener
2、将每个监听器添加到事件派发器中；
            getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
3、派发之前步骤产生的事件；

十一、finishBeanFactoryInitialization(beanFactory); 

主要是初始化所有剩下的单实例bean

一、 finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory)方法

	protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {// Initialize conversion service for this context.// 初始化类型转换组件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.// 添加值解析器if (!beanFactory.hasEmbeddedValueResolver()) {beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));}// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.// 与aspectj相关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.// 主要是这一步，初始化剩下的单实例beanbeanFactory.preInstantiateSingletons();}

二、preInstantiateSingletons()：初始化剩下的单实例bean

@Overridepublic 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.// 获取容器中的所有Bean，依次进行初始化和创建对象，this.beanDefinitionNames里面有所有的bean信息List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);// Trigger initialization of all non-lazy singleton beans...for (String beanName : beanNames) {// 获取Bean的定义信息；RootBeanDefinitionRootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);// 如果Bean不是抽象的，是单实例的，不是懒加载if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {// 判断是否是FactoryBean；是否是实现FactoryBean接口的Beanif (isFactoryBean(beanName)) {// 是工厂Bean。利用getBean(FACTORY_BEAN_PREFIX + beanName);创建对象Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);if (bean instanceof FactoryBean) {final FactoryBean<?> factory = (FactoryBean<?>) bean;boolean isEagerInit;if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {isEagerInit = AccessController.doPrivileged((PrivilegedAction<Boolean>)((SmartFactoryBean<?>) factory)::isEagerInit,getAccessControlContext());}else {isEagerInit = (factory instanceof SmartFactoryBean &&((SmartFactoryBean<?>) factory).isEagerInit());}if (isEagerInit) {getBean(beanName);}}}else {// 不是工厂Bean。利用getBean(beanName);创建对象getBean(beanName);}}}// Trigger post-initialization callback for all applicable beans...
// 所有Bean都利用getBean创建完成以后；检查所有的Bean是否是SmartInitializingSingleton接口的；如果是；就执行afterSingletonsInstantiated()；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();}}}}

三、getBean(String name)

主要就是调用doGetBean方法

		@Overridepublic Object getBean(String name) throws BeansException {return doGetBean(name, null, null, false);}

四、doGetBean(name, null, null, false);

protected <T> T doGetBean(final String name, @Nullable final Class<T> requiredType,@Nullable final Object[] args, boolean typeCheckOnly) throws BeansException {// 先获取名字final String beanName = transformedBeanName(name);Object bean;// Eagerly check singleton cache for manually registered singletons.// 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），主要是先从一级缓存中获取，一级缓存没有就从二级缓存//二级缓存没有就从三级缓存中获取，具体逻辑可以看下面的 getSingleton(beanName)源码Object sharedInstance = getSingleton(beanName);if (sharedInstance != null && args == null) {if (logger.isTraceEnabled()) {if (isSingletonCurrentlyInCreation(beanName)) {logger.trace("Returning eagerly cached instance of singleton bean '" + beanName +"' that is not fully initialized yet - a consequence of a circular reference");}else {logger.trace("Returning cached instance of singleton bean '" + beanName + "'");}}bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);}// 第一次缓存都是没有的，缓存中获取不到，开始Bean的创建对象流程else {// Fail if we're already creating this bean instance:// We're assumably within a circular reference.if (isPrototypeCurrentlyInCreation(beanName)) {throw new BeanCurrentlyInCreationException(beanName);}// Check if bean definition exists in this factory.// 校验是否有父工厂BeanFactory parentBeanFactory = getParentBeanFactory();if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {// Not found -> check parent.String nameToLookup = originalBeanName(name);if (parentBeanFactory instanceof AbstractBeanFactory) {return ((AbstractBeanFactory) parentBeanFactory).doGetBean(nameToLookup, requiredType, args, typeCheckOnly);}else if (args != null) {// Delegation to parent with explicit args.return (T) parentBeanFactory.getBean(nameToLookup, args);}else if (requiredType != null) {// No args -> delegate to standard getBean method.return parentBeanFactory.getBean(nameToLookup, requiredType);}else {return (T) parentBeanFactory.getBean(nameToLookup);}}// 标记当前bean已经被创建if (!typeCheckOnly) {markBeanAsCreated(beanName);}try {// 获取Bean的定义信息final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);checkMergedBeanDefinition(mbd, beanName, args);// Guarantee initialization of beans that the current bean depends on.// 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);try {// 创建依赖对象getBean(dep);}catch (NoSuchBeanDefinitionException ex) {throw new BeanCreationException(mbd.getResourceDescription(), beanName,"'" + beanName + "' depends on missing bean '" + dep + "'", ex);}}}// Create bean instance.// 启动单实例Bean的创建流程if (mbd.isSingleton()) {// 传入一个beanNamme，已经bean的创建工厂进行bean的创建// 对象创建完后会进入getSingleton方法，将创建的Bean添加到缓存中singletonObjectssharedInstance = getSingleton(beanName, () -> {try {// 进入bean的创建流程，具体可看下方createBean(beanName, mbd, args)源码return createBean(beanName, mbd, args);}catch (BeansException ex) {// Explicitly remove instance from singleton cache: It might have been put there// eagerly by the creation process, to allow for circular reference resolution.// Also remove any beans that received a temporary reference to the bean.destroySingleton(beanName);throw ex;}});bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);}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, () -> {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 && !requiredType.isInstance(bean)) {try {T convertedBean = getTypeConverter().convertIfNecessary(bean, requiredType);if (convertedBean == null) {throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());}return convertedBean;}catch (TypeMismatchException ex) {if (logger.isTraceEnabled()) {logger.trace("Failed to convert bean '" + name + "' to required type '" +ClassUtils.getQualifiedName(requiredType) + "'", ex);}throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());}}return (T) bean;}

1、doGetBean()方法中的getSingleton()方法源码

	// 从缓存中获取单实例bean，也就是singletonObjects这个map中获取，allowEarlyReference这个属性是为ture的	@Nullableprotected Object getSingleton(String beanName, boolean allowEarlyReference) {// 先从一级缓存中获取Object singletonObject = this.singletonObjects.get(beanName);if (singletonObject == null && isSingletonCurrentlyInCreation(beanName)) {synchronized (this.singletonObjects) {// 一级缓存没有就从二级缓存获取singletonObject = this.earlySingletonObjects.get(beanName);if (singletonObject == null && allowEarlyReference) {// 二级缓存没有就从三级缓存中获取ObjectFactory<?> singletonFactory = this.singletonFactories.get(beanName);if (singletonFactory != null) {singletonObject = singletonFactory.getObject();this.earlySingletonObjects.put(beanName, singletonObject);this.singletonFactories.remove(beanName);}}}}// 最后返回一个bean，这个单例bean可以为null，主要是@Nullable这个注解return singletonObject;}

2、doGetBean()方法中的createBean()方法源码

@Overrideprotected Object createBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)throws BeanCreationException {if (logger.isTraceEnabled()) {logger.trace("Creating instance of bean '" + beanName + "'");}RootBeanDefinition mbdToUse = mbd;// Make sure bean class is actually resolved at this point, and// clone the bean definition in case of a dynamically resolved Class// which cannot be stored in the shared merged bean definition.// 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 {// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.// 让BeanPostProcessor先拦截返回代理对象 Object bean = resolveBeforeInstantiation(beanName, mbdToUse);if (bean != null) {return bean;}}catch (Throwable ex) {throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName,"BeanPostProcessor before instantiation of bean failed", ex);}try {// 如果前面的InstantiationAwareBeanPostProcessor没有返回代理对象,开始创建beanObject beanInstance = doCreateBean(beanName, mbdToUse, args);if (logger.isTraceEnabled()) {logger.trace("Finished creating instance of bean '" + beanName + "'");}return beanInstance;}catch (BeanCreationException | ImplicitlyAppearedSingletonException ex) {// A previously detected exception with proper bean creation context already,// or illegal singleton state to be communicated up to DefaultSingletonBeanRegistry.throw ex;}catch (Throwable ex) {throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName, "Unexpected exception during bean creation", ex);}}

2.1、createBean()方法中resolveBeforeInstantiation()方法源码

@Nullableprotected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {Object bean = null;if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {// Make sure bean class is actually resolved at this point.// 提前执行InstantiationAwareBeanPostProcessor类型的后置处理器if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {Class<?> targetType = determineTargetType(beanName, mbd);if (targetType != null) {bean = applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);// 如果有返回值：触发postProcessAfterInitialization()；if (bean != null) {// 里面原理与applyBeanPostProcessorsBeforeInstantiation类似bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);}}}mbd.beforeInstantiationResolved = (bean != null);}return bean;}

2.1.1、createBean()方法中resolveBeforeInstantiation()方法里面applyBeanPostProcessorsBeforeInstantiation方法源码

	protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) {for (BeanPostProcessor bp : getBeanPostProcessors()) {// 如果bp是InstantiationAwareBeanPostProcessor类型，就会先触发：postProcessBeforeInstantiation()；if (bp instanceof InstantiationAwareBeanPostProcessor) {InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;Object result = ibp.postProcessBeforeInstantiation(beanClass, beanName);if (result != null) {return result;}}}return null;

2.2、createBean()方法中doCreateBean源码

protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)throws BeanCreationException {// Instantiate the bean.BeanWrapper instanceWrapper = null;if (mbd.isSingleton()) {instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);}if (instanceWrapper == null) {// 创建Bean实例instanceWrapper = createBeanInstance(beanName, mbd, args);}final Object bean = instanceWrapper.getWrappedInstance();Class<?> beanType = instanceWrapper.getWrappedClass();if (beanType != NullBean.class) {mbd.resolvedTargetType = beanType;}// Allow post-processors to modify the merged bean definition.//允许后置处理器修改bean对象信息，主要是调用MergedBeanDefinitionPostProcessor 类型的后置处理器的postProcessMergedBeanDefinition(mbd, beanType, beanName);synchronized (mbd.postProcessingLock) {if (!mbd.postProcessed) {try {applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);}catch (Throwable ex) {throw new BeanCreationException(mbd.getResourceDescription(), beanName,"Post-processing of merged bean definition failed", ex);}mbd.postProcessed = true;}}// Eagerly cache singletons to be able to resolve circular references// even when triggered by lifecycle interfaces like BeanFactoryAware.// 这里其实就是添加各种缓存boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&isSingletonCurrentlyInCreation(beanName));if (earlySingletonExposure) {if (logger.isTraceEnabled()) {logger.trace("Eagerly caching bean '" + beanName +"' to allow for resolving potential circular references");}addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));}// Initialize the bean instance.Object exposedObject = bean;try {// Bean属性赋值populateBean(beanName, mbd, instanceWrapper);// 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，这里bean已经创建好了，主要是先从缓存中获取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<>(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.");}}}}// Register bean as disposable.// 注册Bean的销毁方法try {registerDisposableBeanIfNecessary(beanName, bean, mbd);}catch (BeanDefinitionValidationException ex) {throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);}return exposedObject;}

2.2.1、createBean()方法中doCreateBean方法里面的createBeanInstance方法源码

protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) {// Make sure bean class is actually resolved at this point.// 通过bean名字以及bean的定义信息，解析出bean的类型Class<?> beanClass = resolveBeanClass(mbd, beanName);if (beanClass != null && !Modifier.isPublic(beanClass.getModifiers()) && !mbd.isNonPublicAccessAllowed()) {throw new BeanCreationException(mbd.getResourceDescription(), beanName,"Bean class isn't public, and non-public access not allowed: " + beanClass.getName());}Supplier<?> instanceSupplier = mbd.getInstanceSupplier();if (instanceSupplier != null) {return obtainFromSupplier(instanceSupplier, beanName);}// 通过工厂法创建出bean对象，本质就是利用工厂方法或者对象的构造器创建出Bean实例；if (mbd.getFactoryMethodName() != null) {return instantiateUsingFactoryMethod(beanName, mbd, args);}// Shortcut when re-creating the same bean...boolean resolved = false;boolean autowireNecessary = false;if (args == null) {synchronized (mbd.constructorArgumentLock) {if (mbd.resolvedConstructorOrFactoryMethod != null) {resolved = true;autowireNecessary = mbd.constructorArgumentsResolved;}}}if (resolved) {if (autowireNecessary) {return autowireConstructor(beanName, mbd, null, null);}else {return instantiateBean(beanName, mbd);}}// Candidate constructors for autowiring?Constructor<?>[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);if (ctors != null || mbd.getResolvedAutowireMode() == AUTOWIRE_CONSTRUCTOR ||mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args)) {return autowireConstructor(beanName, mbd, ctors, args);}// Preferred constructors for default construction?ctors = mbd.getPreferredConstructors();if (ctors != null) {return autowireConstructor(beanName, mbd, ctors, null);}// No special handling: simply use no-arg constructor.return instantiateBean(beanName, mbd);}

2.2.1.1、createBean()方法中doCreateBean方法里面的createBeanInstance方法里面的instantiateUsingFactoryMethod源码

	// 利用工厂方法或者对象的构造器创建出Bean实例；protected BeanWrapper instantiateUsingFactoryMethod(String beanName, RootBeanDefinition mbd, @Nullable Object[] explicitArgs) {return new ConstructorResolver(this).instantiateUsingFactoryMethod(beanName, mbd, explicitArgs);}

 2.2.2、createBean()方法中doCreateBean方法里面的populateBean方法源码，主要就是bean赋值

protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {if (bw == null) {if (mbd.hasPropertyValues()) {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;// 赋值之前拿到所有的后置处理器进行遍历if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {for (BeanPostProcessor bp : getBeanPostProcessors()) {if (bp instanceof InstantiationAwareBeanPostProcessor) {// 执行InstantiationAwareBeanPostProcessor后置处理器的postProcessAfterInstantiation()；InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {continueWithPropertyPopulation = false;break;}}}}if (!continueWithPropertyPopulation) {return;}PropertyValues pvs = (mbd.hasPropertyValues() ? mbd.getPropertyValues() : null);if (mbd.getResolvedAutowireMode() == AUTOWIRE_BY_NAME || mbd.getResolvedAutowireMode() == AUTOWIRE_BY_TYPE) {MutablePropertyValues newPvs = new MutablePropertyValues(pvs);// Add property values based on autowire by name if applicable.if (mbd.getResolvedAutowireMode() == AUTOWIRE_BY_NAME) {autowireByName(beanName, mbd, bw, newPvs);}// Add property values based on autowire by type if applicable.if (mbd.getResolvedAutowireMode() == AUTOWIRE_BY_TYPE) {autowireByType(beanName, mbd, bw, newPvs);}pvs = newPvs;}boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();boolean needsDepCheck = (mbd.getDependencyCheck() != AbstractBeanDefinition.DEPENDENCY_CHECK_NONE);PropertyDescriptor[] filteredPds = null;if (hasInstAwareBpps) {if (pvs == null) {pvs = mbd.getPropertyValues();}// 再次拿到后置处理器执行里面得到postProcessPropertyValues()方法for (BeanPostProcessor bp : getBeanPostProcessors()) {if (bp instanceof InstantiationAwareBeanPostProcessor) {InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;PropertyValues pvsToUse = ibp.postProcessProperties(pvs, bw.getWrappedInstance(), beanName);if (pvsToUse == null) {if (filteredPds == null) {filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);}pvsToUse = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);if (pvsToUse == null) {return;}}pvs = pvsToUse;}}}if (needsDepCheck) {if (filteredPds == null) {filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);}checkDependencies(beanName, mbd, filteredPds, pvs);}if (pvs != null) {// 应用Bean属性的值,为属性利用setter方法等进行赋值,主要就是利用反射调用setter方法进行赋值applyPropertyValues(beanName, mbd, bw, pvs);}}

2.2.3、createBean()方法中doCreateBean方法里面的initializeBean方法源码，初始化bean

protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {if (System.getSecurityManager() != null) {AccessController.doPrivileged((PrivilegedAction<Object>) () -> {// 执行Aware接口方法,如果组件实现了BeanNameAware\BeanClassLoaderAware\BeanFactoryAware这几个接口就会执行invokeAwareMethods(beanName, bean);return null;}, getAccessControlContext());}else {invokeAwareMethods(beanName, bean);}Object wrappedBean = bean;if (mbd == null || !mbd.isSynthetic()) {// 执行后置处理器初始化之前的方法，BeanPostProcessor.postProcessBeforeInitialization（）;wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);}try {// 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);}if (mbd == null || !mbd.isSynthetic()) {// 执行后置处理器初始化之后的方法,BeanPostProcessor.postProcessAfterInitialization()；wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);}return wrappedBean;}

2.2.3.1、createBean()方法中doCreateBean方法里面的initializeBean方法里面的invokeInitMethods方法源码解析

protected void invokeInitMethods(String beanName, final Object bean, @Nullable RootBeanDefinition mbd)throws Throwable {boolean isInitializingBean = (bean instanceof InitializingBean);// 是否是InitializingBean接口的实现；执行接口规定的初始化；if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {if (logger.isTraceEnabled()) {logger.trace("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");}if (System.getSecurityManager() != null) {try {AccessController.doPrivileged((PrivilegedExceptionAction<Object>) () -> {((InitializingBean) bean).afterPropertiesSet();return null;}, getAccessControlContext());}catch (PrivilegedActionException pae) {throw pae.getException();}}else {((InitializingBean) bean).afterPropertiesSet();}}// 是否自定义了初始化方法；if (mbd != null && bean.getClass() != NullBean.class) {String initMethodName = mbd.getInitMethodName();if (StringUtils.hasLength(initMethodName) &&!(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&!mbd.isExternallyManagedInitMethod(initMethodName)) {invokeCustomInitMethod(beanName, bean, mbd);}}}

3、getSingleton获取缓存

public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {Assert.notNull(beanName, "Bean name must not be null");synchronized (this.singletonObjects) {Object singletonObject = this.singletonObjects.get(beanName);if (singletonObject == null) {if (this.singletonsCurrentlyInDestruction) {throw new BeanCreationNotAllowedException(beanName,"Singleton bean creation not allowed while singletons of this factory are in destruction " +"(Do not request a bean from a BeanFactory in a destroy method implementation!)");}if (logger.isDebugEnabled()) {logger.debug("Creating shared instance of singleton bean '" + beanName + "'");}beforeSingletonCreation(beanName);boolean newSingleton = false;boolean recordSuppressedExceptions = (this.suppressedExceptions == null);if (recordSuppressedExceptions) {this.suppressedExceptions = new LinkedHashSet<>();}try // 拿到bean对象singletonObject = singletonFactory.getObject();//标记这个bean是新的newSingleton = true;}catch (IllegalStateException ex) {// Has the singleton object implicitly appeared in the meantime ->// if yes, proceed with it since the exception indicates that state.singletonObject = this.singletonObjects.get(beanName);if (singletonObject == null) {throw ex;}}catch (BeanCreationException ex) {if (recordSuppressedExceptions) {for (Exception suppressedException : this.suppressedExceptions) {ex.addRelatedCause(suppressedException);}}throw ex;}finally {if (recordSuppressedExceptions) {this.suppressedExceptions = null;}afterSingletonCreation(beanName);}// 主要是这里，会在这里放入缓存当中if (newSingleton) {addSingleton(beanName, singletonObject);}}return singletonObject;}}

3.1、getSingleton里面的把bean放入缓存addSingleton方法源码

	// 3.1 保存进map当中，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 void addSingleton(String beanName, Object singletonObject) {synchronized (this.singletonObjects) {this.singletonObjects.put(beanName, singletonObject);this.singletonFactories.remove(beanName);this.earlySingletonObjects.remove(beanName);this.registeredSingletons.add(beanName);}}

总结：

finishBeanFactoryInitialization(beanFactory);初始化所有剩下的单实例bean；
    1、beanFactory.preInstantiateSingletons();初始化后剩下的单实例bean
        1）、获取容器中的所有Bean，依次进行初始化和创建对象
        2）、获取Bean的定义信息；RootBeanDefinition
        3）、Bean不是抽象的，是单实例的，是懒加载；
            1）、判断是否是FactoryBean；是否是实现FactoryBean接口的Bean；
            2）、不是工厂Bean。利用getBean(beanName);创建对象
                0、getBean(beanName)； ioc.getBean();
                1、doGetBean(name, null, null, false);
                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
                3、缓存中获取不到，开始Bean的创建对象流程；
                4、标记当前bean已经被创建
                5、获取Bean的定义信息；
                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；】
                7、启动单实例Bean的创建流程；
                    1）、createBean(beanName, mbd, args);
                    2）、Object bean = resolveBeforeInstantiation(beanName, mbdToUse);让BeanPostProcessor先拦截返回代理对象；
                        【InstantiationAwareBeanPostProcessor】：提前执行；
                        先触发：postProcessBeforeInstantiation()；
                        如果有返回值：触发postProcessAfterInitialization()；
                    3）、如果前面的InstantiationAwareBeanPostProcessor没有返回代理对象；调用4）
                    4）、Object beanInstance = doCreateBean(beanName, mbdToUse, args);创建Bean
                         1）、【创建Bean实例】；createBeanInstance(beanName, mbd, args);
                             利用工厂方法或者对象的构造器创建出Bean实例；
                         2）、applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
                             调用MergedBeanDefinitionPostProcessor的postProcessMergedBeanDefinition(mbd, beanType, beanName);
                         3）、【Bean属性赋值】populateBean(beanName, mbd, instanceWrapper);
                             赋值之前：
                             1）、拿到InstantiationAwareBeanPostProcessor后置处理器；
                                 postProcessAfterInstantiation()；
                             2）、拿到InstantiationAwareBeanPostProcessor后置处理器；
                                 postProcessPropertyValues()；
                             =====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);
                         4）、【Bean初始化】initializeBean(beanName, exposedObject, mbd);
                             1）、【执行Aware接口方法】invokeAwareMethods(beanName, bean);执行xxxAware接口的方法
                                 BeanNameAware\BeanClassLoaderAware\BeanFactoryAware
                             2）、【执行后置处理器初始化之前】applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
                                 BeanPostProcessor.postProcessBeforeInitialization（）;
                             3）、【执行初始化方法】invokeInitMethods(beanName, wrappedBean, mbd);
                                 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；
                             4）、【执行后置处理器初始化之后】applyBeanPostProcessorsAfterInitialization
                                 BeanPostProcessor.postProcessAfterInitialization()；
                         5）、注册Bean的销毁方法；
                    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。。。。；
        所有Bean都利用getBean创建完成以后；
            检查所有的Bean是否是SmartInitializingSingleton接口的；如果是；就执行afterSingletonsInstantiated()；

 十二、finishRefresh()

完成BeanFactory的初始化创建工作；IOC容器就创建完成；

protected void finishRefresh() {// Clear context-level resource caches (such as ASM metadata from scanning).// 清理resource资源缓存clearResourceCaches();// Initialize lifecycle processor for this context.// 初始化和生命周期有关的后置处理器initLifecycleProcessor();// Propagate refresh to lifecycle processor first.// 拿到前面定义的生命周期处理器（BeanFactory）；回调onRefresh()；getLifecycleProcessor().onRefresh();// Publish the final event.// 发布容器刷新完成事件；publishEvent(new ContextRefreshedEvent(this));// Participate in LiveBeansView MBean, if active.// 暴露MBeanLiveBeansView.registerApplicationContext(this);}

 

	protected void initLifecycleProcessor() {ConfigurableListableBeanFactory beanFactory = getBeanFactory();// 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；if (beanFactory.containsLocalBean(LIFECYCLE_PROCESSOR_BEAN_NAME)) {// spring允许我们重写LifecycleProcessor实现类，可以重写里面的方法，在刷新完成或者关闭的时候做一些操作。this.lifecycleProcessor =beanFactory.getBean(LIFECYCLE_PROCESSOR_BEAN_NAME, LifecycleProcessor.class);if (logger.isTraceEnabled()) {logger.trace("Using LifecycleProcessor [" + this.lifecycleProcessor + "]");}}else {DefaultLifecycleProcessor defaultProcessor = new DefaultLifecycleProcessor();defaultProcessor.setBeanFactory(beanFactory);this.lifecycleProcessor = defaultProcessor;beanFactory.registerSingleton(LIFECYCLE_PROCESSOR_BEAN_NAME, this.lifecycleProcessor);if (logger.isTraceEnabled()) {logger.trace("No '" + LIFECYCLE_PROCESSOR_BEAN_NAME + "' bean, using " +"[" + this.lifecycleProcessor.getClass().getSimpleName() + "]");}}}

二、spring容器创建源码总结

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）、使用xml文件注册bean，例如使用<bean>标签进行注册
        2）、使用注解注册Bean，例如@Service、@Component、@Bean、xxx
2、Spring容器会在合适的时机创建这些Bean
        1）、在用到这个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；就是在finishBeanFactoryInitialization()；这个步骤创建剩下的所有对象。
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....
            增强的功能注解：
            AsyncAnnotationBeanPostProcessor
            ....
4、事件驱动模型；
        ApplicationListener；监听器，用于事件监听；
        ApplicationEventMulticaster；多波器，用于事件派发：