Spring读源码系列07----容器扩展功能--中

protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// Tell the internal bean factory to use the context's class loader etc.
		beanFactory.setBeanClassLoader(getClassLoader());
		if (!shouldIgnoreSpel) {
			beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		}
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// Configure the bean factory with context callbacks.
		//重点关注这里
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
		...
	}

             //populateBean对bean进行属性赋值  
			populateBean(beanName, mbd, instanceWrapper);
			//对bean完成相关初始化操作
			exposedObject = initializeBean(beanName, exposedObject, mbd);

	protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
		if (System.getSecurityManager() != null) {
			AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
				invokeAwareMethods(beanName, bean);
				return null;
			}, getAccessControlContext());
		}
		else {
		//对实现了BeanNameAware，BeanClassLoaderAware和BeanFactoryAware接口的类进行相关注入处理
			invokeAwareMethods(beanName, bean);
		}
            
		Object wrappedBean = bean;
		//isSynthetic是否是应用程序自身产生的bean,如果是返回false
		//如果不是，说明是用户自定义的bean,需要被后置处理器处理
		if (mbd == null || !mbd.isSynthetic()) {
		//应用后置处理器进行前置处理
			wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
		}

		try {
		//触发相关初始化方法
			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()) {
			//应用bean的后置处理
			wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
		}

		return wrappedBean;
	}

	private void invokeAwareMethods(String beanName, Object bean) {
		if (bean instanceof Aware) {
		//注入beanName
			if (bean instanceof BeanNameAware) {
				((BeanNameAware) bean).setBeanName(beanName);
			}
	    //注入加载当前bean的类加载器		
			if (bean instanceof BeanClassLoaderAware) {
				ClassLoader bcl = getBeanClassLoader();
				if (bcl != null) {
					((BeanClassLoaderAware) bean).setBeanClassLoader(bcl);
				}
			}
	//注入BeanFactory		
			if (bean instanceof BeanFactoryAware) {
				((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
			}
		}
	}

	@Override
	public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)
			throws BeansException {
 
		Object result = existingBean;
		for (BeanPostProcessor processor : getBeanPostProcessors()) {
			Object current = processor.postProcessBeforeInitialization(result, beanName);
			if (current == null) {
				return result;
			}
			result = current;
		}
		return result;
	}

	protected void invokeInitMethods(String beanName, Object bean, @Nullable RootBeanDefinition mbd)
			throws Throwable {

		boolean isInitializingBean = (bean instanceof InitializingBean);
		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 {
			//如果当前bean实现了InitializingBean，会调用其的afterPropertiesSet方法
			//因为initializeBean方法执行是在populateBean方法之后，也就是属性注入完成之后，因此该初始化方法就被称为了afterPropertiesSet，很形象
				((InitializingBean) bean).afterPropertiesSet();
			}
		}
        //会尝试调用当前bean实现的init-method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);
			}
		}
	}

	@Override
	public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
			throws BeansException {
        
		Object result = existingBean;
		for (BeanPostProcessor processor : getBeanPostProcessors()) {
			Object current = processor.postProcessAfterInitialization(result, beanName);
			if (current == null) {
				return result;
			}
			result = current;
		}
		return result;
	}

class ApplicationContextAwareProcessor implements BeanPostProcessor {

	private final ConfigurableApplicationContext applicationContext;

	private final StringValueResolver embeddedValueResolver;


	/**
	 * Create a new ApplicationContextAwareProcessor for the given context.
	 */
	public ApplicationContextAwareProcessor(ConfigurableApplicationContext applicationContext) {
		this.applicationContext = applicationContext;
		this.embeddedValueResolver = new EmbeddedValueResolver(applicationContext.getBeanFactory());
	}


	@Override
	@Nullable
	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
	//没有实现上面这些规定需要被当前处理器处理注入的aware接口，就跳过不进行处理
		if (!(bean instanceof EnvironmentAware || bean instanceof EmbeddedValueResolverAware ||
				bean instanceof ResourceLoaderAware || bean instanceof ApplicationEventPublisherAware ||
				bean instanceof MessageSourceAware || bean instanceof ApplicationContextAware ||
				bean instanceof ApplicationStartupAware)) {
			return bean;
		}

		AccessControlContext acc = null;

		if (System.getSecurityManager() != null) {
			acc = this.applicationContext.getBeanFactory().getAccessControlContext();
		}

		if (acc != null) {
			AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
				invokeAwareInterfaces(bean);
				return null;
			}, acc);
		}
		else {
		//对实现了aware接口的bean进行处理
			invokeAwareInterfaces(bean);
		}

		return bean;
	}

//相信不需要我多说了
	private 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 ApplicationStartupAware) {
			((ApplicationStartupAware) bean).setApplicationStartup(this.applicationContext.getApplicationStartup());
		}
		if (bean instanceof ApplicationContextAware) {
			((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
		}
	}

}

	protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// Tell the internal bean factory to use the context's class loader etc.
		beanFactory.setBeanClassLoader(getClassLoader());
		if (!shouldIgnoreSpel) {
			beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		}
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// Configure the bean factory with context callbacks.
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
        
        //已经分析到这里了
		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.ignoreDependencyInterface(ApplicationStartupAware.class); 
		...
	}

//确定给定的 bean 属性是否从依赖项检查中排除。此实现不包括由 CGLIB 定义的属性以及其类型与忽略的依赖类型匹配或由忽略的依赖接口定义的属性。
	protected boolean isExcludedFromDependencyCheck(PropertyDescriptor pd) {
		return (AutowireUtils.isExcludedFromDependencyCheck(pd) ||
				this.ignoredDependencyTypes.contains(pd.getPropertyType()) ||
				AutowireUtils.isSetterDefinedInInterface(pd, this.ignoredDependencyInterfaces));
	}

//确定给定的 bean 属性是否从依赖项检查中排除。此实现不包括 CGLIB 定义的属性
	public static boolean isExcludedFromDependencyCheck(PropertyDescriptor pd) {
	//当前需要被注入的属性，在对应的类中必须有相关联的set方法
		Method wm = pd.getWriteMethod();
		//没有的话，返回false
		if (wm == null) {
			return false;
		}
		//不是代理类直接返回false
		if (!wm.getDeclaringClass().getName().contains("$$")) {
			// Not a CGLIB method so it's OK.
			return false;
		}
		//是代理类的话，通过判断父类，即被代理类是否存在对应的set方法来决定是否可以完成依赖注入
		// It was declared by CGLIB, but we might still want to autowire it
		// if it was actually declared by the superclass.
		Class<?> superclass = wm.getDeclaringClass().getSuperclass();
		return !ClassUtils.hasMethod(superclass, wm);
	}

//返回给定 bean 属性的 setter 方法是否在任何给定接口中定义。
	public static boolean isSetterDefinedInInterface(PropertyDescriptor pd, Set<Class<?>> interfaces) {
		Method setter = pd.getWriteMethod();
		if (setter != null) {
			Class<?> targetClass = setter.getDeclaringClass();
			for (Class<?> ifc : interfaces) {
				if (ifc.isAssignableFrom(targetClass) && ClassUtils.hasMethod(ifc, setter)) {
					return true;
				}
			}
		}
		return false;
	}

//返回未满足的非简单 bean 属性数组。这些可能是对工厂中其他 bean 的不满意引用。不包括简单的属性，如原语或字符串
	protected String[] unsatisfiedNonSimpleProperties(AbstractBeanDefinition mbd, BeanWrapper bw) {
		Set<String> result = new TreeSet<>();
		PropertyValues pvs = mbd.getPropertyValues();
		PropertyDescriptor[] pds = bw.getPropertyDescriptors();
		for (PropertyDescriptor pd : pds) {
			//当前需要进行依赖注入的属性必须有对应的set方法
			if (pd.getWriteMethod() != null 
			//当前需要进行依赖注入的属性并非被排除的接口,例如：aware的相关注入会被忽略
			&& !isExcludedFromDependencyCheck(pd) && 
           //必须有这个属性值存在
           !pvs.contains(pd.getName()) &&
					//不是简单类型
					!BeanUtils.isSimpleProperty(pd.getPropertyType())) {
               
               //如果当前属性满足条件，会将当前属性名加入结果集中
				result.add(pd.getName());
			}
		}
		return StringUtils.toStringArray(result);
	}

	public static boolean isSimpleValueType(Class<?> type) {
		return (Void.class != type && void.class != type &&
				(ClassUtils.isPrimitiveOrWrapper(type) ||
				Enum.class.isAssignableFrom(type) ||
				CharSequence.class.isAssignableFrom(type) ||
				Number.class.isAssignableFrom(type) ||
				Date.class.isAssignableFrom(type) ||
				Temporal.class.isAssignableFrom(type) ||
				URI.class == type ||
				URL.class == type ||
				Locale.class == type ||
				Class.class == type));
	}

	protected void autowireByName(
			String beanName, AbstractBeanDefinition mbd, BeanWrapper bw, MutablePropertyValues pvs) {
       //获取到需要被依赖注入的属性
		String[] propertyNames = unsatisfiedNonSimpleProperties(mbd, bw);
		for (String propertyName : propertyNames) {
			if (containsBean(propertyName)) {
			//递归创建，如果已经创建了，直接返回
				Object bean = getBean(propertyName);
				//原本可能propertyName关联的是一个bean的引用字符串，现在我们把字符串引用的bean，换成了真实被引用bean的实例
				//准备属性集合，在applyPropertyValues方法中真正完成属性的注入
				pvs.add(propertyName, bean);
				registerDependentBean(propertyName, beanName);
				if (logger.isTraceEnabled()) {
					logger.trace("Added autowiring by name from bean name '" + beanName +
							"' via property '" + propertyName + "' to bean named '" + propertyName + "'");
				}
			}
			else {
				if (logger.isTraceEnabled()) {
					logger.trace("Not autowiring property '" + propertyName + "' of bean '" + beanName +
							"' by name: no matching bean found");
				}
			}
		}
	}

	protected void autowireByType(
			String beanName, AbstractBeanDefinition mbd, BeanWrapper bw, MutablePropertyValues pvs) {

		TypeConverter converter = getCustomTypeConverter();
		if (converter == null) {
			converter = bw;
		}

		Set<String> autowiredBeanNames = new LinkedHashSet<>(4);
		//同样先拿到需要注入的依赖集合
		String[] propertyNames = unsatisfiedNonSimpleProperties(mbd, bw);
		for (String propertyName : propertyNames) {
			try {
			//拿到当前属性对应的描述符
				PropertyDescriptor pd = bw.getPropertyDescriptor(propertyName);
				// Don't try autowiring by type for type Object: never makes sense,
				// even if it technically is a unsatisfied, non-simple property.
				if (Object.class != pd.getPropertyType()) {
					//拿到当前属性对应的get方法
					MethodParameter methodParam = BeanUtils.getWriteMethodParameter(pd);
					// Do not allow eager init for type matching in case of a prioritized post-processor.
					boolean eager = !(bw.getWrappedInstance() instanceof PriorityOrdered);
					//按照类型进行查找，最终得到当前属性引用的真实的bean实例
					DependencyDescriptor desc = new AutowireByTypeDependencyDescriptor(methodParam, eager);
					Object autowiredArgument = resolveDependency(desc, beanName, autowiredBeanNames, converter);
					if (autowiredArgument != null) {
					//加入属性集合，在applyPropertyValues方法中真正完成属性的注入
						pvs.add(propertyName, autowiredArgument);
					}
					for (String autowiredBeanName : autowiredBeanNames) {
						registerDependentBean(autowiredBeanName, beanName);
						if (logger.isTraceEnabled()) {
							logger.trace("Autowiring by type from bean name '" + beanName + "' via property '" +
									propertyName + "' to bean named '" + autowiredBeanName + "'");
						}
					}
					autowiredBeanNames.clear();
				}
			}
			catch (BeansException ex) {
				throw new UnsatisfiedDependencyException(mbd.getResourceDescription(), beanName, propertyName, ex);
			}
		}
	}

	protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// Tell the internal bean factory to use the context's class loader etc.
		beanFactory.setBeanClassLoader(getClassLoader());
		if (!shouldIgnoreSpel) {
			beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		}
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// Configure the bean factory with context callbacks.
		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.ignoreDependencyInterface(ApplicationStartupAware.class);

		// BeanFactory interface not registered as resolvable type in a plain factory.
		// MessageSource registered (and found for autowiring) as a bean.
		//注册依赖
		beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
		beanFactory.registerResolvableDependency(ResourceLoader.class, this);
		beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
		beanFactory.registerResolvableDependency(ApplicationContext.class, this);
....
	}

	@Override
	public void registerResolvableDependency(Class<?> dependencyType, @Nullable Object autowiredValue) {
		Assert.notNull(dependencyType, "Dependency type must not be null");
		if (autowiredValue != null) {
			if (!(autowiredValue instanceof ObjectFactory || dependencyType.isInstance(autowiredValue))) {
				throw new IllegalArgumentException("Value [" + autowiredValue +
						"] does not implement specified dependency type [" + dependencyType.getName() + "]");
			}
			//最终是加入resolvableDependencies集合
			//从依赖类型映射到相应的自动装配值。
			this.resolvableDependencies.put(dependencyType, autowiredValue);
		}
	}

	protected Map<String, Object> findAutowireCandidates(
			@Nullable String beanName, Class<?> requiredType, DependencyDescriptor descriptor) {
        //获取给定类型的所有 bean 名称
		String[] candidateNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
				this, requiredType, true, descriptor.isEager());
		Map<String, Object> result = CollectionUtils.newLinkedHashMap(candidateNames.length);
		//此处会查看resolvableDependencies集合
		for (Map.Entry<Class<?>, Object> classObjectEntry : this.resolvableDependencies.entrySet()) {
			Class<?> autowiringType = classObjectEntry.getKey();
			//如果需要的类型刚好在已经解析好依赖的集合中,那么直接注入即可
			if (autowiringType.isAssignableFrom(requiredType)) {
			//拿到解析好的值
				Object autowiringValue = classObjectEntry.getValue();
				//对ObjectFactory做特殊处理
				autowiringValue = AutowireUtils.resolveAutowiringValue(autowiringValue, requiredType);
				//如果需要的类型与autowiringValue 一致，那么就放入结果集合中，然后退出循环
				if (requiredType.isInstance(autowiringValue)) {
					result.put(ObjectUtils.identityToString(autowiringValue), autowiringValue);
					break;
				}
			}
		}
		for (String candidate : candidateNames) {
			if (!isSelfReference(beanName, candidate) && isAutowireCandidate(candidate, descriptor)) {
				addCandidateEntry(result, candidate, descriptor, requiredType);
			}
		}
		if (result.isEmpty()) {
			boolean multiple = indicatesMultipleBeans(requiredType);
			// Consider fallback matches if the first pass failed to find anything...
			DependencyDescriptor fallbackDescriptor = descriptor.forFallbackMatch();
			for (String candidate : candidateNames) {
				if (!isSelfReference(beanName, candidate) && isAutowireCandidate(candidate, fallbackDescriptor) &&
						(!multiple || getAutowireCandidateResolver().hasQualifier(descriptor))) {
					addCandidateEntry(result, candidate, descriptor, requiredType);
				}
			}
			if (result.isEmpty() && !multiple) {
				// Consider self references as a final pass...
				// but in the case of a dependency collection, not the very same bean itself.
				for (String candidate : candidateNames) {
					if (isSelfReference(beanName, candidate) &&
							(!(descriptor instanceof MultiElementDescriptor) || !beanName.equals(candidate)) &&
							isAutowireCandidate(candidate, fallbackDescriptor)) {
						addCandidateEntry(result, candidate, descriptor, requiredType);
					}
				}
			}
		}
		return result;
	}

	@Nullable
	protected String determineAutowireCandidate(Map<String, Object> candidates, DependencyDescriptor descriptor) {
		Class<?> requiredType = descriptor.getDependencyType();
		String primaryCandidate = determinePrimaryCandidate(candidates, requiredType);
		if (primaryCandidate != null) {
			return primaryCandidate;
		}
		String priorityCandidate = determineHighestPriorityCandidate(candidates, requiredType);
		if (priorityCandidate != null) {
			return priorityCandidate;
		}
		// Fallback
		for (Map.Entry<String, Object> entry : candidates.entrySet()) {
			String candidateName = entry.getKey();
			Object beanInstance = entry.getValue();
			if ((beanInstance != null && this.resolvableDependencies.containsValue(beanInstance)) ||
					matchesBeanName(candidateName, descriptor.getDependencyName())) {
				return candidateName;
			}
		}
		return null;
	}

@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			StartupStep contextRefresh = this.applicationStartup.start("spring.context.refresh");

			// 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.
				//允许在上下文子类中对 bean 工厂进行后处理,该方法默认为空实现
				postProcessBeanFactory(beanFactory);

				StartupStep beanPostProcess = this.applicationStartup.start("spring.context.beans.post-process");
				// Invoke factory processors registered as beans in the context.
				//调用在上下文中注册为 bean 的工厂处理器。
				//我们要重点分析的方法!!!
				invokeBeanFactoryPostProcessors(beanFactory);

....
	}

	protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
	//触发所有的BeanFactory的后置处理逻辑
		PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
       
        //代理处理
		// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
		// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
		if (!NativeDetector.inNativeImage() && beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
			beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
			beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
		}
	}

	/** BeanFactoryPostProcessors to apply on refresh. */
	private final List<BeanFactoryPostProcessor> beanFactoryPostProcessors = new ArrayList<>();

final class PostProcessorRegistrationDelegate {

	private PostProcessorRegistrationDelegate() {
	}
    
    //这段代码有接近200行，官方也给出了一段为何不重构这段代码的理由，我们先来看一下:
    //警告：虽然看起来可以轻松地重构此方法的主体以避免使用多个循环和多个列表，但使用多个列表和多次传递处理器名称是有意的。
    //我们必须确保我们遵守 PriorityOrdered 和 Ordered 处理器的合同。
    //具体来说，我们不能导致处理器被实例化（通过 getBean() 调用）或以错误的顺序在 ApplicationContext 中注册。
	public static void invokeBeanFactoryPostProcessors(
			ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {

		// Invoke BeanDefinitionRegistryPostProcessors first, if any.
		//如果有的话，首先调用 BeanDefinitionRegistryPostProcessors。
		Set<String> processedBeans = new HashSet<>();
         //DefaultListableBeanFactory实现了beanFactory接口
         //并且默认传入的beanFactory也是DefaultListableBeanFactory
		if (beanFactory instanceof BeanDefinitionRegistry) {
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
            
            //先循环遍历外部传入的beanFactoryPostProcessors
			for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
			//判断是否是BeanDefinitionRegistryPostProcessor,这是一个接口，下面有个非常有用的实现类
			//专门用来处理@Configuration注解--》ConfigurationClassPostProcessor
				if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
					BeanDefinitionRegistryPostProcessor registryProcessor =
							(BeanDefinitionRegistryPostProcessor) postProcessor;
					//调用该类型的bean工厂后置处理器的postProcessBeanDefinitionRegistry	
					registryProcessor.postProcessBeanDefinitionRegistry(registry);
					//调用完后放入registryProcessors集合中
					registryProcessors.add(registryProcessor);
				}
				else {
				//否则直接加入regularPostProcessors集合
					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.
			//翻译：
			//不要在此处初始化 FactoryBeans：我们需要让所有常规 bean 保持未初始化状态，
			//以便 bean 工厂后处理器应用到它们！将实现 PriorityOrdered、Ordered 和其余部分的           
			//BeanDefinitionRegistryPostProcessor 分开。
			List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

			// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
			//首先处理实现了PriorityOrdered接口的工厂后置处理器
			String[] postProcessorNames =
			//获取实现了BeanDefinitionRegistryPostProcessor接口的bean
			//第二个参数为true表名可以获取到非单例的bean
			//第三个参数为false控制是否去初始化lazy-init的单例bean和被FactoryBean创建的bean
			//该方法返回当前类型bean在容器中对应的所有beanName----因为实现该接口的bean可能存在多个
					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
			//判断当前查找出来的BeanFactoryPostProcessor是否实现了PriorityOrdered接口
				if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				//加入currentRegistryProcessors集合
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			//按照ordered大小进行排序处理
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			registryProcessors.addAll(currentRegistryProcessors);
			//调用每个BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
			currentRegistryProcessors.clear();

			// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
			//和上面差不多，是用来处理实现了ordered接口的BeanDefinitionRegistryPostProcessor
			postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {
				if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			registryProcessors.addAll(currentRegistryProcessors);
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
			currentRegistryProcessors.clear();


			// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
			//
			boolean reiterate = true;
			while (reiterate) {
				reiterate = false;
				//获取实现了BeanDefinitionRegistryPostProcessor接口的bean
				postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
				for (String ppName : postProcessorNames) {
				//当前bean如果在上面被处理过了，就跳过
					if (!processedBeans.contains(ppName)) {
						currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
						processedBeans.add(ppName);
						reiterate = true;
					}
				}
				//currentRegistryProcessors集合存放当前需要被处理的处理器
				sortPostProcessors(currentRegistryProcessors, beanFactory);
				registryProcessors.addAll(currentRegistryProcessors);
				invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
				currentRegistryProcessors.clear();
			}

			// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
			//触发BeanFactoryPostProcessor的postProcessBeanFactory方法
			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!
		//在容器中拿到所有BeanFactoryPostProcessor类型的bean
		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) {
		//跳过第一阶段已经被处理过的bean
			if (processedBeans.contains(ppName)) {
				// skip - already processed in first phase above
			}
			//分别将实现了PriorityOrdered，Ordered和啥都没实现的BeanFactoryPostProcessor放入不同的集合
			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);
			}
		}
        //优先处理实现了priorityOrdered接口的后置处理器
		// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

        //再处理实现了ordered接口的处理器
		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
		for (String postProcessorName : orderedPostProcessorNames) {
			orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

//最后处理没有实现任何优先级接口的普通工厂bean后置处理器
		// Finally, invoke all other BeanFactoryPostProcessors.
		List<BeanFactoryPostProcessor> 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...
		beanFactory.clearMetadataCache();
	}

//注册拦截 bean 创建的 bean 处理器。
public static void registerBeanPostProcessors(
			ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {

//警告：虽然看起来可以轻松地重构此方法的主体以避免使用多个循环和多个列表，
//但使用多个列表和多次传递处理器名称是有意的。
//我们必须确保我们遵守 PriorityOrdered 和 Ordered 处理器的合同。
//具体来说，我们不能导致处理器被实例化（通过 getBean() 调用）或以错误的顺序在 ApplicationContext 中注册。
      
//拿到容器中所有实现了BeanPostProcessor接口的bean
		String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);

//注册 BeanPostProcessorChecker，
//它会在 BeanPostProcessor 实例化期间创建 bean 时记录一条信息消息，
//即当 bean 不符合所有 BeanPostProcessor 处理的条件时。
		int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
		beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

        //分别处理实现了priorityOrdered,ordered和啥都没有实现的以及内部使用的bean的后置处理器
		// 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<>();
		for (String ppName : postProcessorNames) {
			if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
				BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
				priorityOrderedPostProcessors.add(pp);
				//MergedBeanDefinitionPostProcessor---合并bean的定义
				//例如: AutowiredAnnotationBeanPostProcessor处理autowired注解
				if (pp instanceof MergedBeanDefinitionPostProcessor) {
					internalPostProcessors.add(pp);
				}
			}
			else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
				orderedPostProcessorNames.add(ppName);
			}
			else {
				nonOrderedPostProcessorNames.add(ppName);
			}
		}

        //先处理PriorityOrdered，然后注册
		// First, register the BeanPostProcessors that implement PriorityOrdered.
		sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
		registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

        //再处理oreder接口
		// Next, register the BeanPostProcessors that implement Ordered.
		List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
		for (String ppName : orderedPostProcessorNames) {
			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
			orderedPostProcessors.add(pp);
			//判断是否是MergedBeanDefinitionPostProcessor
			if (pp instanceof MergedBeanDefinitionPostProcessor) {
				internalPostProcessors.add(pp);
			}
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		registerBeanPostProcessors(beanFactory, orderedPostProcessors);

		// Now, register all regular BeanPostProcessors.
		//处理没有实现任何优先级接口的bean
		List<BeanPostProcessor> 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.
		//再处理internalPostProcessors即MergedBeanDefinitionPostProcessor集合
		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));
	}

//对处理器进行排序
	private static void sortPostProcessors(List<?> postProcessors, ConfigurableListableBeanFactory beanFactory) {
		// Nothing to sort?
		if (postProcessors.size() <= 1) {
			return;
		}
		//靠getOrder返回值来判断
		Comparator<Object> comparatorToUse = null;
		if (beanFactory instanceof DefaultListableBeanFactory) {
			comparatorToUse = ((DefaultListableBeanFactory) beanFactory).getDependencyComparator();
		}
		if (comparatorToUse == null) {
			comparatorToUse = OrderComparator.INSTANCE;
		}
		postProcessors.sort(comparatorToUse);
	}

	/**
	 * Invoke the given BeanDefinitionRegistryPostProcessor beans.
	 */
	private static void invokeBeanDefinitionRegistryPostProcessors(
			Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry, ApplicationStartup applicationStartup) {

		for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
			StartupStep postProcessBeanDefRegistry = applicationStartup.start("spring.context.beandef-registry.post-process")
					.tag("postProcessor", postProcessor::toString);
			//调用	BeanDefinitionRegistryPostProcessor 的	postProcessBeanDefinitionRegistry方法
			postProcessor.postProcessBeanDefinitionRegistry(registry);
			postProcessBeanDefRegistry.end();
		}
	}

	/**
	 * Invoke the given BeanFactoryPostProcessor beans.
	 */
	private static void invokeBeanFactoryPostProcessors(
			Collection<? extends BeanFactoryPostProcessor> postProcessors, ConfigurableListableBeanFactory beanFactory) {

		for (BeanFactoryPostProcessor postProcessor : postProcessors) {
			StartupStep postProcessBeanFactory = beanFactory.getApplicationStartup().start("spring.context.bean-factory.post-process")
					.tag("postProcessor", postProcessor::toString);
			//调用	BeanFactoryPostProcessor的postProcessBeanFactory方法
			postProcessor.postProcessBeanFactory(beanFactory);
			postProcessBeanFactory.end();
		}
	}

	/**
	 * Register the given BeanPostProcessor beans.手动往beanFactory中注册一些postProcessors
	 */
	private static void registerBeanPostProcessors(
			ConfigurableListableBeanFactory beanFactory, List<BeanPostProcessor> postProcessors) {

		if (beanFactory instanceof AbstractBeanFactory) {
			// Bulk addition is more efficient against our CopyOnWriteArrayList there
			((AbstractBeanFactory) beanFactory).addBeanPostProcessors(postProcessors);
		}
		else {
			for (BeanPostProcessor postProcessor : postProcessors) {
				beanFactory.addBeanPostProcessor(postProcessor);
			}
		}
	}


	/**
	 * BeanPostProcessor 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.
	 */
	private static final class BeanPostProcessorChecker implements BeanPostProcessor {

		private static final Log logger = LogFactory.getLog(BeanPostProcessorChecker.class);

		private final ConfigurableListableBeanFactory beanFactory;

		private final int beanPostProcessorTargetCount;

		public BeanPostProcessorChecker(ConfigurableListableBeanFactory beanFactory, int beanPostProcessorTargetCount) {
			this.beanFactory = beanFactory;
			this.beanPostProcessorTargetCount = beanPostProcessorTargetCount;
		}

		@Override
		public Object postProcessBeforeInitialization(Object bean, String beanName) {
			return bean;
		}

		@Override
		public Object postProcessAfterInitialization(Object bean, String beanName) {
			if (!(bean instanceof BeanPostProcessor) && !isInfrastructureBean(beanName) &&
					this.beanFactory.getBeanPostProcessorCount() < this.beanPostProcessorTargetCount) {
				if (logger.isInfoEnabled()) {
					logger.info("Bean '" + beanName + "' of type [" + bean.getClass().getName() +
							"] is not eligible for getting processed by all BeanPostProcessors " +
							"(for example: not eligible for auto-proxying)");
				}
			}
			return bean;
		}

		private boolean isInfrastructureBean(@Nullable String beanName) {
			if (beanName != null && this.beanFactory.containsBeanDefinition(beanName)) {
				BeanDefinition bd = this.beanFactory.getBeanDefinition(beanName);
				return (bd.getRole() == RootBeanDefinition.ROLE_INFRASTRUCTURE);
			}
			return false;
		}
	}

}

//BeanFactoryPostProcessor 用于@Configuration 类的引导处理。
//使用 或 时默认注册。否则，可以像任何其他 BeanFactoryPostProcessor 一样手动声明。
//这个后处理器是按优先级排序的，因为在 @Configuration 类中声明的任何 @Bean 方法都必须在任何其他 BeanFactoryPostProcessor 执行之前注册其相应的 bean 定义，这一点很重要。
public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPostProcessor,
		PriorityOrdered, ResourceLoaderAware, ApplicationStartupAware, BeanClassLoaderAware, EnvironmentAware {

//使用完全限定类名作为默认 bean 名的 BeanNameGenerator。
//可以通过 setBeanNameGenerator 覆盖此用于配置级别导入的默认值。请注意，组件扫描的默认值是一个普通的 
//AnnotationBeanNameGenerator.INSTANCE，除非通过 setBeanNameGenerator 使用统一的用户级 bean 名称生成器覆盖。
	public static final AnnotationBeanNameGenerator IMPORT_BEAN_NAME_GENERATOR =
	//默认beanName为ClassName
			FullyQualifiedAnnotationBeanNameGenerator.INSTANCE;

	private static final String IMPORT_REGISTRY_BEAN_NAME =
			ConfigurationClassPostProcessor.class.getName() + ".importRegistry";


	private final Log logger = LogFactory.getLog(getClass());

	private SourceExtractor sourceExtractor = new PassThroughSourceExtractor();

	private ProblemReporter problemReporter = new FailFastProblemReporter();

	@Nullable
	private Environment environment;

	private ResourceLoader resourceLoader = new DefaultResourceLoader();

	@Nullable
	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

//这个工厂类生产出来的MetadataReader比较重要，使用它我们可以很方便的获取当前class类的一些元数据信息
//底层使用asm框架读取并解析class文件，然后封装class类本身的一些元数据信息
	private MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory();

	private boolean setMetadataReaderFactoryCalled = false;

	private final Set<Integer> registriesPostProcessed = new HashSet<>();

	private final Set<Integer> factoriesPostProcessed = new HashSet<>();

//负责解析ConfigurationClass配置类---类比xmlBeanDefinitionReader解析xml的过程
	@Nullable
	private ConfigurationClassBeanDefinitionReader reader;

	private boolean localBeanNameGeneratorSet = false;

	/* Using short class names as default bean names by default. */
	private BeanNameGenerator componentScanBeanNameGenerator = AnnotationBeanNameGenerator.INSTANCE;

	/* Using fully qualified class names as default bean names by default. */
	private BeanNameGenerator importBeanNameGenerator = IMPORT_BEAN_NAME_GENERATOR;

	private ApplicationStartup applicationStartup = ApplicationStartup.DEFAULT;


	@Override
	public int getOrder() {
		return Ordered.LOWEST_PRECEDENCE;  // within PriorityOrdered
	}


	public void setSourceExtractor(@Nullable SourceExtractor sourceExtractor) {
		this.sourceExtractor = (sourceExtractor != null ? sourceExtractor : new PassThroughSourceExtractor());
	}


	public void setProblemReporter(@Nullable ProblemReporter problemReporter) {
		this.problemReporter = (problemReporter != null ? problemReporter : new FailFastProblemReporter());
	}


	public void setMetadataReaderFactory(MetadataReaderFactory metadataReaderFactory) {
		Assert.notNull(metadataReaderFactory, "MetadataReaderFactory must not be null");
		this.metadataReaderFactory = metadataReaderFactory;
		this.setMetadataReaderFactoryCalled = true;
	}


	public void setBeanNameGenerator(BeanNameGenerator beanNameGenerator) {
		Assert.notNull(beanNameGenerator, "BeanNameGenerator must not be null");
		this.localBeanNameGeneratorSet = true;
		this.componentScanBeanNameGenerator = beanNameGenerator;
		this.importBeanNameGenerator = beanNameGenerator;
	}

	@Override
	public void setEnvironment(Environment environment) {
		Assert.notNull(environment, "Environment must not be null");
		this.environment = environment;
	}

	@Override
	public void setResourceLoader(ResourceLoader resourceLoader) {
		Assert.notNull(resourceLoader, "ResourceLoader must not be null");
		this.resourceLoader = resourceLoader;
		if (!this.setMetadataReaderFactoryCalled) {
			this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);
		}
	}

	@Override
	public void setBeanClassLoader(ClassLoader beanClassLoader) {
		this.beanClassLoader = beanClassLoader;
		if (!this.setMetadataReaderFactoryCalled) {
			this.metadataReaderFactory = new CachingMetadataReaderFactory(beanClassLoader);
		}
	}

	@Override
	public void setApplicationStartup(ApplicationStartup applicationStartup) {
		this.applicationStartup = applicationStartup;
	}

	/**
	 * Derive further bean definitions from the configuration classes in the registry.
	 */
	@Override
	public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
		int registryId = System.identityHashCode(registry);
		if (this.registriesPostProcessed.contains(registryId)) {
			throw new IllegalStateException(
					"postProcessBeanDefinitionRegistry already called on this post-processor against " + registry);
		}
		if (this.factoriesPostProcessed.contains(registryId)) {
			throw new IllegalStateException(
					"postProcessBeanFactory already called on this post-processor against " + registry);
		}
		this.registriesPostProcessed.add(registryId);
        //处理配置类里面的bean定义
		processConfigBeanDefinitions(registry);
	}

	/**
通过将配置类替换为 CGLIB 增强的子类来准备在运行时为 bean 请求提供服务的配置类
	 */
	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		int factoryId = System.identityHashCode(beanFactory);
		if (this.factoriesPostProcessed.contains(factoryId)) {
			throw new IllegalStateException(
					"postProcessBeanFactory already called on this post-processor against " + beanFactory);
		}
		this.factoriesPostProcessed.add(factoryId);
		//当前beanFactory没有被postProcessBeanDefinitionRegistry方法处理过
		if (!this.registriesPostProcessed.contains(factoryId)) {
			// BeanDefinitionRegistryPostProcessor hook apparently not supported...
			// Simply call processConfigurationClasses lazily at this point then.
			//那就处理他
			processConfigBeanDefinitions((BeanDefinitionRegistry) beanFactory);
		}
        
        //生成代理类
		enhanceConfigurationClasses(beanFactory);
		//为当前beanFactory增加一个ImportAwareBeanPostProcessor
		beanFactory.addBeanPostProcessor(new ImportAwareBeanPostProcessor(beanFactory));
	}

	/**
Build and validate a configuration model based on the registry of Configuration classes.
	 */
	public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
//存放所有配置类
		List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
		String[] candidateNames = registry.getBeanDefinitionNames();
        
		for (String beanName : candidateNames) {
			BeanDefinition beanDef = registry.getBeanDefinition(beanName);
			//判断当前标注了@configuration 注解的类是否已经被处理过了
			if (beanDef.getAttribute(ConfigurationClassUtils.CONFIGURATION_CLASS_ATTRIBUTE) != null) {
				if (logger.isDebugEnabled()) {
					logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
				}
			}
			//检查bean是否标注了Configuration注解，或者是一个内部类被标注了Configuration或者component注解都会被自动注册
			else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
			//加入配置类集合
				configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
			}
		}

		// Return immediately if no @Configuration classes were found
		//当然容器中没有标注@Configuration的类
		if (configCandidates.isEmpty()) {
			return;
		}

		// Sort by previously determined @Order value, if applicable
		//对配置类进行进行排序---按照@Order注解指定的大小进行排序
		configCandidates.sort((bd1, bd2) -> {
			int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
			int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
			return Integer.compare(i1, i2);
		});

		// Detect any custom bean name generation strategy supplied through the enclosing application context
		//我们可以设置beanName生成器来覆盖默认的,默认的方式是类名小写
		SingletonBeanRegistry sbr = null;
		if (registry instanceof SingletonBeanRegistry) {
			sbr = (SingletonBeanRegistry) registry;
			if (!this.localBeanNameGeneratorSet) {
				BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(
						AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR);
				if (generator != null) {
					this.componentScanBeanNameGenerator = generator;
					this.importBeanNameGenerator = generator;
				}
			}
		}

		if (this.environment == null) {
			this.environment = new StandardEnvironment();
		}

		// Parse each @Configuration class
		//负责解析每个标注了@Configuration注解的类
		ConfigurationClassParser parser = new ConfigurationClassParser(
				this.metadataReaderFactory, this.problemReporter, this.environment,
				this.resourceLoader, this.componentScanBeanNameGenerator, registry);
       
       //拿到当前容器中所有配置类集合
		Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
		//负责存放已经解析好的配置类集合
		Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());
		do {
			StartupStep processConfig = this.applicationStartup.start("spring.context.config-classes.parse");
			//负责解析配置类--该过程会详细讲解!!!
			parser.parse(candidates);
			//配置类可能不是最终的（CGLIB 限制），除非它声明 proxyBeanMethods=false
			parser.validate();
             
             //获得解析后得到的ConfigurationClass集合
			Set<ConfigurationClass> configClasses = new LinkedHashSet<>(parser.getConfigurationClasses());
			//移除哪些已经解析好的
			configClasses.removeAll(alreadyParsed);

			// Read the model and create bean definitions based on its content
			if (this.reader == null) {
				this.reader = new ConfigurationClassBeanDefinitionReader(
						registry, this.sourceExtractor, this.resourceLoader, this.environment,
						this.importBeanNameGenerator, parser.getImportRegistry());
			}
			//加载配置类中的bean定义
			this.reader.loadBeanDefinitions(configClasses);
			alreadyParsed.addAll(configClasses);
			processConfig.tag("classCount", () -> String.valueOf(configClasses.size())).end();

			candidates.clear();
			if (registry.getBeanDefinitionCount() > candidateNames.length) {
				String[] newCandidateNames = registry.getBeanDefinitionNames();
				Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));
				Set<String> alreadyParsedClasses = new HashSet<>();
				for (ConfigurationClass configurationClass : alreadyParsed) {
					alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
				}
				for (String candidateName : newCandidateNames) {
					if (!oldCandidateNames.contains(candidateName)) {
						BeanDefinition bd = registry.getBeanDefinition(candidateName);
						if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) &&
								!alreadyParsedClasses.contains(bd.getBeanClassName())) {
							candidates.add(new BeanDefinitionHolder(bd, candidateName));
						}
					}
				}
				candidateNames = newCandidateNames;
			}
		}
		while (!candidates.isEmpty());

		// Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
		if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
			sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
		}

		if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
			// Clear cache in externally provided MetadataReaderFactory; this is a no-op
			// for a shared cache since it'll be cleared by the ApplicationContext.
			((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
		}
	}



//下面的大家就自己看一下吧,难点在于enhanceConfigurationClasses方法，可能比较难理解
	/**
	 * Post-processes a BeanFactory in search of Configuration class BeanDefinitions;
	 * any candidates are then enhanced by a ConfigurationClassEnhancer
	 * Candidate status is determined by BeanDefinition attribute metadata.
	 */
	public void enhanceConfigurationClasses(ConfigurableListableBeanFactory beanFactory) {
		StartupStep enhanceConfigClasses = this.applicationStartup.start("spring.context.config-classes.enhance");
		Map<String, AbstractBeanDefinition> configBeanDefs = new LinkedHashMap<>();
		for (String beanName : beanFactory.getBeanDefinitionNames()) {
			BeanDefinition beanDef = beanFactory.getBeanDefinition(beanName);
			Object configClassAttr = beanDef.getAttribute(ConfigurationClassUtils.CONFIGURATION_CLASS_ATTRIBUTE);
			AnnotationMetadata annotationMetadata = null;
			MethodMetadata methodMetadata = null;
			if (beanDef instanceof AnnotatedBeanDefinition) {
				AnnotatedBeanDefinition annotatedBeanDefinition = (AnnotatedBeanDefinition) beanDef;
				annotationMetadata = annotatedBeanDefinition.getMetadata();
				methodMetadata = annotatedBeanDefinition.getFactoryMethodMetadata();
			}
			if ((configClassAttr != null || methodMetadata != null) && beanDef instanceof AbstractBeanDefinition) {
				// Configuration class (full or lite) or a configuration-derived @Bean method
				// -> eagerly resolve bean class at this point, unless it's a 'lite' configuration
				// or component class without @Bean methods.
				AbstractBeanDefinition abd = (AbstractBeanDefinition) beanDef;
				if (!abd.hasBeanClass()) {
					boolean liteConfigurationCandidateWithoutBeanMethods =
							(ConfigurationClassUtils.CONFIGURATION_CLASS_LITE.equals(configClassAttr) &&
								annotationMetadata != null && !ConfigurationClassUtils.hasBeanMethods(annotationMetadata));
					if (!liteConfigurationCandidateWithoutBeanMethods) {
						try {
							abd.resolveBeanClass(this.beanClassLoader);
						}
						catch (Throwable ex) {
							throw new IllegalStateException(
									"Cannot load configuration class: " + beanDef.getBeanClassName(), ex);
						}
					}
				}
			}
			if (ConfigurationClassUtils.CONFIGURATION_CLASS_FULL.equals(configClassAttr)) {
				if (!(beanDef instanceof AbstractBeanDefinition)) {
					throw new BeanDefinitionStoreException("Cannot enhance @Configuration bean definition '" +
							beanName + "' since it is not stored in an AbstractBeanDefinition subclass");
				}
				else if (logger.isInfoEnabled() && beanFactory.containsSingleton(beanName)) {
					logger.info("Cannot enhance @Configuration bean definition '" + beanName +
							"' since its singleton instance has been created too early. The typical cause " +
							"is a non-static @Bean method with a BeanDefinitionRegistryPostProcessor " +
							"return type: Consider declaring such methods as 'static'.");
				}
				configBeanDefs.put(beanName, (AbstractBeanDefinition) beanDef);
			}
		}
		if (configBeanDefs.isEmpty() || NativeDetector.inNativeImage()) {
			// nothing to enhance -> return immediately
			enhanceConfigClasses.end();
			return;
		}

		ConfigurationClassEnhancer enhancer = new ConfigurationClassEnhancer();
		for (Map.Entry<String, AbstractBeanDefinition> entry : configBeanDefs.entrySet()) {
			AbstractBeanDefinition beanDef = entry.getValue();
			// If a @Configuration class gets proxied, always proxy the target class
			beanDef.setAttribute(AutoProxyUtils.PRESERVE_TARGET_CLASS_ATTRIBUTE, Boolean.TRUE);
			// Set enhanced subclass of the user-specified bean class
			Class<?> configClass = beanDef.getBeanClass();
			Class<?> enhancedClass = enhancer.enhance(configClass, this.beanClassLoader);
			if (configClass != enhancedClass) {
				if (logger.isTraceEnabled()) {
					logger.trace(String.format("Replacing bean definition '%s' existing class '%s' with " +
							"enhanced class '%s'", entry.getKey(), configClass.getName(), enhancedClass.getName()));
				}
				beanDef.setBeanClass(enhancedClass);
			}
		}
		enhanceConfigClasses.tag("classCount", () -> String.valueOf(configBeanDefs.keySet().size())).end();
	}


	private static class ImportAwareBeanPostProcessor implements InstantiationAwareBeanPostProcessor {

		private final BeanFactory beanFactory;

		public ImportAwareBeanPostProcessor(BeanFactory beanFactory) {
			this.beanFactory = beanFactory;
		}

		@Override
		public PropertyValues postProcessProperties(@Nullable PropertyValues pvs, Object bean, String beanName) {
			// Inject the BeanFactory before AutowiredAnnotationBeanPostProcessor's
			// postProcessProperties method attempts to autowire other configuration beans.
			if (bean instanceof EnhancedConfiguration) {
				((EnhancedConfiguration) bean).setBeanFactory(this.beanFactory);
			}
			return pvs;
		}

		@Override
		public Object postProcessBeforeInitialization(Object bean, String beanName) {
			if (bean instanceof ImportAware) {
				ImportRegistry ir = this.beanFactory.getBean(IMPORT_REGISTRY_BEAN_NAME, ImportRegistry.class);
				AnnotationMetadata importingClass = ir.getImportingClassFor(ClassUtils.getUserClass(bean).getName());
				if (importingClass != null) {
					((ImportAware) bean).setImportMetadata(importingClass);
				}
			}
			return bean;
		}
	}

}