/*** Central method of this class: creates a bean instance,* populates the bean instance, applies post-processors, etc.** @see #doCreateBean*/
@Override
protected Object createBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)throws BeanCreationException {// 省略......try {/*** 注释1. InstantiationAwareBeanPostProcessor#postProcessorsBeforeInstantiation触发入口*/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);}// 省略......try {/*** 注释2. postProcessAfterInstantiation、postProcessProperties 触发入口* 主要逻辑都在doCreateBean()方法中，* 方法中包含了实例化、属性赋值、初始化过程。逻辑很清晰* 这三个方法与三个生命周期阶段一一对应，非常重要*/Object 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);}
}

/** 注释1 代码进入后执行InstantiationAwareBeanPostProcessor#ostProcessBeforeInstantiation方法*/
@Nullable
protected 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.if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {Class<?> targetType = determineTargetType(beanName, mbd);if (targetType != null) {/*** 注释3：回调beanPostProcessorsBeforeInstantiation实例化，如果返回bean非null则直接执行* 不为空null就直接返回了而不执行doCreateBean()方法了，而该方法是创建Bean对象的方法* beanPostProcessorsAfterInitialization进行实例初始化*/bean = applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);if (bean != null) {/** 注释4 */bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);}}}mbd.beforeInstantiationResolved = (bean != null);}return bean;
}/**注释3 代码跟进*/
@Nullable
protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) {for (BeanPostProcessor bp : getBeanPostProcessors()) {if (bp instanceof InstantiationAwareBeanPostProcessor) {/*** 注释5：只要其中一个postProcessBeforeInstantiation返回实例bean即结束回调，* 这个bean将会直接返回给bean容器管理*/InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;Object result = ibp.postProcessBeforeInstantiation(beanClass, beanName);if (result != null) {return result;}}}return null;
}/** 注释4 代码跟进*/
@Override
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)throws BeansException {Object result = existingBean;for (BeanPostProcessor processor : getBeanPostProcessors()) {/**注释6 */Object current = processor.postProcessAfterInitialization(result, beanName);if (current == null) {return result;}result = current;}return result;
}

protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)throws BeanCreationException {BeanWrapper instanceWrapper = null;if (mbd.isSingleton()) {instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);}if (instanceWrapper == null) {/**  注释7 实例化阶段！ */instanceWrapper = createBeanInstance(beanName, mbd, args);}// 省略......// Initialize the bean instance.Object exposedObject = bean;try {/** 注释8 依据bean definition 完成bean属性赋值 */populateBean(beanName, mbd, instanceWrapper);/** 注释9 执行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);}}// 省略......return exposedObject;
}

protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {// 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;// InstantiationAwareBeanPostProcessor#postProcessAfterInstantiation()/*** 注释10：满足两个要求：* 1、BeanDefinition为应用程序bean，而非基础框架bean信息。* 2、注册过InstantiationAwareBeanPostProcessor类型接口，上文有提到这个标志位。* 3、注册了多个接口时，只要其中一个postProcessAfterInstantiation返回false，即停止后续执行。*/ if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {for (BeanPostProcessor bp : getBeanPostProcessors()) {if (bp instanceof InstantiationAwareBeanPostProcessor) {InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {continueWithPropertyPopulation = false;break;}}}}// 忽略后续的属性赋值操作代码
}

public interface ApplicationContext extends EnvironmentCapable, ListableBeanFactory, HierarchicalBeanFactory,MessageSource, ApplicationEventPublisher, ResourcePatternResolver {}

// 注释9 代码进入 调用初始化阶段
protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {// 注释11 这里调用的是Group1中的三个Bean开头的AwareinvokeAwareMethods(beanName, bean);Object wrappedBean = bean;/** * 这里调用的是Group2中的几个Aware，* 而实质上这里就是前面所说的BeanPostProcessor的调用点！* 也就是说与Group1中的Aware不同，这里是通过BeanPostProcessor（ApplicationContextAwareProcessor）实现的。*//** 注释12 */wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);/** 注释13 下文即将介绍的InitializingBean调用点 */invokeInitMethods(beanName, wrappedBean, mbd);/** 注释14 BeanPostProcessor的另一个调用点*/wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);return wrappedBean;
}/**注释11 代码进入 */
private void invokeAwareMethods(final String beanName, final Object bean) {if (bean instanceof Aware) {if (bean instanceof BeanNameAware) {((BeanNameAware) bean).setBeanName(beanName);}if (bean instanceof BeanClassLoaderAware) {((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());}if (bean instanceof BeanFactoryAware) {((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);}}
}

@Overridepublic void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {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.// 所有BeanPostProcesser初始化的调用点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.// 所有单例非懒加载Bean的调用点finishBeanFactoryInitialization(beanFactory);// Last step: publish corresponding event.finishRefresh();}}

// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 首先，加入实现了PriorityOrdered接口的BeanPostProcessors，顺便根据PriorityOrdered排了序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.
// 然后，加入实现了Ordered接口的BeanPostProcessors，顺便根据Ordered排了序postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);for (String ppName : postProcessorNames) {if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));processedBeans.add(ppName);}}sortPostProcessors(currentRegistryProcessors, beanFactory);registryProcessors.addAll(currentRegistryProcessors);invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);currentRegistryProcessors.clear();// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 最后加入其他常规的BeanPostProcessorsboolean 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();}// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 首先，加入实现了PriorityOrdered接口的BeanPostProcessors，顺便根据PriorityOrdered排了序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.
// 然后，加入实现了Ordered接口的BeanPostProcessors，顺便根据Ordered排了序postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);for (String ppName : postProcessorNames) {if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));processedBeans.add(ppName);}}sortPostProcessors(currentRegistryProcessors, beanFactory);registryProcessors.addAll(currentRegistryProcessors);invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);currentRegistryProcessors.clear();// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
// 最后加入其他常规的BeanPostProcessorsboolean 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();}

/*** Useful constant for the highest precedence value.* @see java.lang.Integer#MIN_VALUE*/int HIGHEST_PRECEDENCE = Integer.MIN_VALUE;/*** Useful constant for the lowest precedence value.* @see java.lang.Integer#MAX_VALUE*/int LOWEST_PRECEDENCE = Integer.MAX_VALUE;