Springboot浅析(三)——容器刷新流程

(二)BeanDefinitionRegistryPostProcessor——bean定义注册表后置处理

BeanFactoryPostProcessor的子接口,多了一个postProcessBeanDefinitionRegistry方法,这个方法允许在Bean实例化之前对BeanDefinitionRegistry(bean定义注册表)进行后置处理。

(三)BeanPostProcessor——bean后置处理器

提供对实例化后的bean进行后置处理的扩展点。一般用于对将要实例化到容器的bean进行再次加工。

(四)MergedBeanDefinitionPostProcessor——合并Bean定义后置处理器

BeanPostProcessor的子接口,多一个postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName) 方法,用于后置处理合并Bean定义。

二、容器刷新流程

(一)主要代码

//最终调到AbstractApplicationContext的refresh方法
public void refresh() throws BeansException, IllegalStateException {
    synchronized (this.startupShutdownMonitor) {
        // Prepare this context for refreshing.
        // 初始化前的预处理,初始化Environment里面的PropertySources(猜测是webXML里面的东西),debug下没有什么用
        prepareRefresh();

        // Tell the subclass to refresh the internal bean factory.
        //  获取BeanFactory,直接返回的是前面初始化的beanFactory,只不过设置了一下SerializationId
        ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

        // Prepare the bean factory for use in this context.
        // 3. BeanFactory的预处理配置
	//(1) 在容器注册了ApplicationContextAwareProcessor这个Bean后置处理器用于处理实现了XXXAware接口的bean,调用其setXXX方法。
	//(2)忽略一些自动注入,以及添加一些自动注入的支持,为什么要忽略这些自动注入勒,因为当beanDefinition的AutowireMode为1(按setXXX方法的名称进行注入)和2(按setXXX方法返回值类型进行自动注入)时,若自动注入生效,该Bean的setXXX方法将被自动注入,那么为了避免和XXXAware接口冲突,所以进行了忽略。
	//(3) 添加一些自动注入支持,包含BeanFactory,ResourceLoader,ApplicationEventPublisher,ApplicationContext。
	//(4) 在容器注册了new ApplicationListenerDetector(this)这个Bean后置处理器用于收集所有实现了ApplicationListener接口的bean并收集到容器中的一个集合中。
        prepareBeanFactory(beanFactory);

        try {
            // Allows post-processing of the bean factory in context subclasses.
            // 4. 准备BeanFactory完成后进行的后置处理
	    //以servlet环境为例:
	    //(1) 添加了一个bean的后置处理器处理ServletContextAware和ServletConfigAware,用于注入ServletContext和ServletConfig。
	    //(2) 往容器注册Scope,Scope描述的是Spring容器如何新建Bean实例的,这里注册了Request以及Session两个Scope并且注册ServletRequest、ServletResponse、HttpSession、WebRequest为自动装配。
	    //(3)当判断容器的basePackages属性不为null的时候进行包扫描(但debug下这里没执行)。
	    //(4)当判断容器的annotatedClasses属性不为null也进行注册(debug下没执行)。
            postProcessBeanFactory(beanFactory);

            // Invoke factory processors registered as beans in the context.
            // 5. 执行BeanFactory创建后的后置处理器,
			// 这一步里面会处理ConfigurationClassPostProcessor这个bd后置处理器完成所有的bd注册
            invokeBeanFactoryPostProcessors(beanFactory);

            // Register bean processors that intercept bean creation.
            // 6. 注册Bean的后置处理器
            registerBeanPostProcessors(beanFactory);

            // Initialize message source for this context.
            // 7. 初始化MessageSource
            initMessageSource();

            // Initialize event multicaster for this context.
            // 8. 初始化事件派发器
            initApplicationEventMulticaster();

            // Initialize other special beans in specific context subclasses.
            // 9. 子类的多态onRefresh
            onRefresh();

            // Check for listener beans and register them.
            // 10. 注册监听器
            registerListeners();
            //到此为止,BeanFactory已创建完成
            // Instantiate all remaining (non-lazy-init) singletons.
            // 11. 初始化所有剩下的单例Bean
            finishBeanFactoryInitialization(beanFactory);
            // Last step: publish corresponding event.
            // 12. 完成容器的创建工作
            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...
            // 13. 清除缓存
            resetCommonCaches();
        }
    }
}

(二)核心点

1.prepareBeanFactory(beanFactory)-BeanFactory的预处理配置

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、表达式解析器等
   beanFactory.setBeanClassLoader(getClassLoader());
   beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
   beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

   // Configure the bean factory with context callbacks.
   //  配置一个BeanPostProcessor,这个Bean后处理器将实现了以下几个Aware的bean分别回调对应的方法
   beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
	// 配置ignoreDependencyInterface,是的这些类型自动装配无效,但实测@Autowired注入时还是能装配,故这里的意思是为了避免其他bd设置了自动注入,即AutowireMode,而不是指使用@Autowired注解进行的依赖注入。
   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.
   // 自动注入的支持
   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.
   // 配置一个可加载所有监听器的组件
   beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));

   // Detect a LoadTimeWeaver and prepare for weaving, if found.
   if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
       beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
       // Set a temporary ClassLoader for type matching.
       beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
   }

   // Register default environment beans.
   // 注册了默认的运行时环境、系统配置属性、系统环境的信息
   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());
   }
}

这里主要干了四件事:

  1. 在容器注册了ApplicationContextAwareProcessor这个Bean后置处理器用于处理实现了XXXAware接口的bean,调用其setXXX方法。
  2. 忽略一些自动注入,以及添加一些自动注入的支持,为什么要忽略这些自动注入勒,因为当beanDefinition的AutowireMode为1(按setXXX方法的名称进行注入)和2(按setXXX方法返回值类型进行自动注入)时,若自动注入生效,该Bean的setXXX方法将被自动注入,那么为了避免和XXXAware接口冲突,所以进行了忽略。
  3. 添加一些自动注入支持,包含BeanFactory,ResourceLoader,ApplicationEventPublisher,ApplicationContext。
  4. 在容器注册了new ApplicationListenerDetector(this)这个Bean后置处理器用于收集所有实现了ApplicationListener接口的bean并收集到容器中的一个集合中。

2.postProcessBeanFactory(beanFactory)-准备BeanFactory完成后进行的后置处理

以servlet为例:这里的ApplicationContext实现实际上为AnnotationConfigServletWebServerApplicationContext。在AnnotationConfigServletWebServerApplicationContext类中该方法主要是完成了:

  1. 往容器注册了一个bean的后置处理器处理ServletContextAware和ServletConfigAware,用于注入ServletContext和ServletConfig。
  2. 往容器注册Scope,Scope描述的是Spring容器如何新建Bean实例的,这里注册了Request以及Session两个Scope并且注册ServletRequest、ServletResponse、HttpSession、WebRequest为自动装配。
  3. 当判断容器的basePackages属性不为null的时候进行包扫描(但debug下这里没执行)。
  4. 当判断容器的annotatedClasses属性不为null也进行注册(debug下没执行)。

3.invokeBeanFactoryPostProcessors(beanFactory)-执行BeanFactory创建后的后置处理器

代码:

protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
    // 执行BeanFactory后置处理器
    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()));
    }
}

进入 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors()):

public static void invokeBeanFactoryPostProcessors(
        ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {

    // Invoke BeanDefinitionRegistryPostProcessors first, if any.
    //用于存放已经执行了的processedBeans
    Set<String> processedBeans = new HashSet<>();

    // 这里要判断BeanFactory的类型,默认SpringBoot创建的BeanFactory是DefaultListableBeanFactory
    // 这个类实现了BeanDefinitionRegistry接口,则此if结构必进
    if (beanFactory instanceof BeanDefinitionRegistry) {
        BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
        List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<>();
        List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<>();
		//遍历已经注册到beanFactory的BeanFactoryPostProcessor后置处理器,然后分类为regularPostProcessors和registryProcessors
        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.
     	//这个currentRegistryProcessors变量用于分阶段执行方法,因为有PriorityOrdered和Ordered接口的存在
        List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
  
        // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
        // 首先,调用实现PriorityOrdered接口的BeanDefinitionRegistryPostProcessors并添加到processedBeans
        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);
            }
        }
		//排序
        sortPostProcessors(currentRegistryProcessors, beanFactory);
        //添加到registryProcessors
        registryProcessors.addAll(currentRegistryProcessors);
        //执行
        invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
        currentRegistryProcessors.clear();

        // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
        // 接下来,调用实现Ordered接口的BeanDefinitionRegistryPostProcessors。
        postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
        for (String ppName : postProcessorNames) {
            if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
                currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
                processedBeans.add(ppName);
            }
        }
		//排序
        sortPostProcessors(currentRegistryProcessors, beanFactory);
        //添加到registryProcessors
		registryProcessors.addAll(currentRegistryProcessors);
		//执行
        invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
        currentRegistryProcessors.clear();

        // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
        // 最后,调用所有其他BeanDefinitionRegistryPostProcessor
        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;
                }
            }
			//排序添加执行
            sortPostProcessors(currentRegistryProcessors, beanFactory);
            registryProcessors.addAll(currentRegistryProcessors);
            invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
            currentRegistryProcessors.clear();
        }

        // Now, invoke the postProcessBeanFactory callback of all processors handled so far.
        // 回调所有BeanFactoryPostProcessor的postProcessBeanFactory方法
        invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
        invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
        // 先回调BeanDefinitionRegistryPostProcessor的postProcessBeanFactory方法
        // 再调用BeanFactoryPostProcessor的postProcessBeanFactory方法
    }

    // 如果BeanFactory没有实现BeanDefinitionRegistry接口,则进入下面的代码流程
    else {
        // Invoke factory processors registered with the context instance.
        // 调用在上下文实例中注册的工厂处理器。
        invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
    }

    // 下面的部分是回调BeanFactoryPostProcessor,思路与上面的几乎一样
  
    // Do not initialize FactoryBeans here: We need to leave all regular beans
    // uninitialized to let the bean factory post-processors apply to them!
    String[] postProcessorNames =
            beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

    // Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
    // Ordered, and the rest.
    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
        }
        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...
    // 清理缓存
    beanFactory.clearMetadataCache();
}

上面代码有点长主要干得事有:

  1. 第一步获取已经注册到容器(与beanDifinitionMap相区别,这里用了容器内beanFactoryPostProcessors这个变量存的而不是从beanDefinition获取的)的beanFactoryPostProcessor的beanFactoryPostProcessors,并筛选实现了BeanDefinitionRegistryPostProcessor接口的,执行其postProcessBeanDefinitionRegistry方法.
  2. 第二步获取容器内已注册的beanDefinition中BeanDefinitionRegistryPostProcessor类型的bean,筛选实现了PriorityOrdered接口的,进行排序,然后回调其postProcessBeanDefinitionRegistry。这里执行最重要的ConfigurationClassPostProcessor,他会对当前beandifinitonMap中的带有configraution注解的进行处理,比如处理@Component 、@ComponentScan 、@Import 、@ImportResource、@PropertySource 、@ComponentScan 、@Import 、@ImportResource 、@Bean注解,注册所有的beanDefinition,等一下展开讲这个ConfigurationClassPostProcessor。
  3. 第三步获取容器内已注册的beanDefinition中BeanDefinitionRegistryPostProcessor类型的bean,会根据是否实现PriorityOrdered接口Ordered接口进行排序(大体顺序是PriorityOrdered优先Ordered优先没实现接口的,同一接口的按方法返回值确定顺序),然后调用其postProcessBeanDefinitionRegistry方法。
  4. 第四步执行上面所有beanDefinitionRegistryPostProcessor类型的bean的postBeanFactory方法。
  5. 第五步对于ApplicationContext内(与beanDifinitionMap相区别,这里用了beanFactoryPostProcessors这个变量存而不是beanDefinition存)的beanFactoryPostProcessor,不属于BeanDefinitionRegistryPostProcessor接口的(即只是BeanFactoryProcessor),调用其postBeanFactory方法。
  6. 第六步调用其他所有BeanFactoryPostProcessor的postBeanFactory方法,也会解析PriorityOrdered及Ordered接口。

接下来重点看一看在第二步执行的ConfigurationClassPostProcessor的源码,内部就不详细展开了,大概的流程已经写入注释中:

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);
    processConfigBeanDefinitions(registry);
}

这里的意思是获取容器Id,获取其是否调用过,如果没有则继续执行processConfigBeanDefinitions。看一看 processConfigBeanDefinitions(registry)方法:

public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
    List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
    String[] candidateNames = registry.getBeanDefinitionNames();

    // 确定配置类和组件
	//带有@Configuration注解的bd的configurationClass值设为full,
	//带有@Component 、@ComponentScan 、@Import 、@ImportResource注解或方法中添加了带@Bean的方法
	//(只是将带bean的方法收集起来,并没有注册bd)的设为configurationClass值设为lite,并加入到configCandidates
    for (String beanName : candidateNames) {
        BeanDefinition beanDef = registry.getBeanDefinition(beanName);
        if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
                ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
            if (logger.isDebugEnabled()) {
                logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
            }
        }
        else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
            configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
        }
    }

    // Return immediately if no @Configuration classes were found
    if (configCandidates.isEmpty()) {
        return;
    }

    // Sort by previously determined @Order value, if applicable
    // 对配置类进行排序
    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
    // 加载获取BeanNameGenerator
    SingletonBeanRegistry sbr = null;
    if (registry instanceof SingletonBeanRegistry) {
        sbr = (SingletonBeanRegistry) registry;
        if (!this.localBeanNameGeneratorSet) {
            BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(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
    // 初始化配置类解析器
    ConfigurationClassParser parser = new ConfigurationClassParser(
            this.metadataReaderFactory, this.problemReporter, this.environment,
            this.resourceLoader, this.componentScanBeanNameGenerator, registry);
	//需要解析的配置类集合
    Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
    //已经解析的配置类集合
	Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());
    do {
        // 解析配置类,最重要的方法
		//对configCandidates按照@Order进行排序并遍历进行递归一直解析父类,
		//需解析@PropertySource 、@ComponentScan 、@Import 、@ImportResource 、@Bean注解(注这一步还没有对扫描到的组件完全进行Bd注册,
		//而只是注册了包扫描到的bd以及处理@Import注解时实现了ImportBeanDefinitionRegistrar或者ImportSelector接口的bd,
		//并且这里会先处理一个类的嵌套配置类)
        parser.parse(candidates);
		//校验
        parser.validate();
        Set<ConfigurationClass> configClasses = new LinkedHashSet<>(parser.getConfigurationClasses());
        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());
        }
        //解析配置类中的内容
		//将通过@Import、@Bean注解方式注册的类以及处理@ImportResource注解引入的配置文件解析成BeanDefinition,然后注册到BeanDefinitionMap中。
        this.reader.loadBeanDefinitions(configClasses);
        alreadyParsed.addAll(configClasses);
        candidates.clear();
        if (registry.getBeanDefinitionCount() > candidateNames.length) {
		   //当前的bdNames
            String[] newCandidateNames = registry.getBeanDefinitionNames();
			//上一次解析之前的bdNames
            Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));
			//这次解析的bdNames
            Set<String> alreadyParsedClasses = new HashSet<>();
            for (ConfigurationClass configurationClass : alreadyParsed) {
                alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
            }
			//遍历当前bdNames,若不是以前有的,并且是配置类,并且没有被解析到,则添加到candidates,下一次循环再解析一次
            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
    // 将ImportRegistry注册为Bean,以支持ImportAware 和@Configuration类
    if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
        sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
    }

    // 清除缓存
    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();
    }
}

4.registerBeanPostProcessors(beanFactory)-注册bean后置处理器(包含MergedBeanDefinitionPostProcessor)

注册逻辑跟注册beanFactoryPostProcessor差不多,注册顺序都会判断priorityOrdered与Ordered接口,并且先注册MergedBeanDefinitionPostProcessor再注册beanFactoryPostProcessor。

这里有两个MergedBeanDefinitionPostProcessor,一个是AutowiredAnnotationBeanPostProcessor,一个是ApplicationListenerDetector。

---------------------------- 困了,未完待续