请别再问Spring Bean的生命周期了

// 忽略了无关代码
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)
      throws BeanCreationException {

   // Instantiate the bean.
   BeanWrapper instanceWrapper = null;
   if (instanceWrapper == null) {
       // 实例化阶段！
      instanceWrapper = createBeanInstance(beanName, mbd, args);
   }

   // Initialize the bean instance.
   Object exposedObject = bean;
   try {
       // 属性赋值阶段！
      populateBean(beanName, mbd, instanceWrapper);
       // 初始化阶段！
      exposedObject = initializeBean(beanName, exposedObject, mbd);
   }
}

InstantiationAwareBeanPostProcessor extends BeanPostProcessor

@Override
protected Object createBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)
        throws BeanCreationException {

    try {
        // Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
        // postProcessBeforeInstantiation方法调用点，这里就不跟进了，
        // 有兴趣的同学可以自己看下，就是for循环调用所有的InstantiationAwareBeanPostProcessor
        Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
        if (bean != null) {
            return bean;
        }
    }
    
    try {   
        // 上文提到的doCreateBean方法，可以看到
        // postProcessBeforeInstantiation方法在创建Bean之前调用
        Object beanInstance = doCreateBean(beanName, mbdToUse, args);
        if (logger.isTraceEnabled()) {
            logger.trace("Finished creating instance of bean '" + beanName + "'");
        }
        return beanInstance;
    }  
}

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()
    // 方法作为属性赋值的前置检查条件，在属性赋值之前执行，能够影响是否进行属性赋值！
   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 {
          
}

// 见名知意，初始化阶段调用的方法
protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {

    // 这里调用的是Group1中的三个Bean开头的Aware
    invokeAwareMethods(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。
    wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
    // 下文即将介绍的InitializingBean调用点
    invokeInitMethods(beanName, wrappedBean, mbd);
    // BeanPostProcessor的另一个调用点
    wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);

    return wrappedBean;
}

@Override
public 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BeanPostProcessors
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();
}

/**
 * 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;