Spring AbstractApplicationContext抽象类的refresh()方法--笔记

Spring中AbstractApplicationContext抽象类的refresh()方法是用来刷新Spring的应用上下文的。下面Spring的应用上下文我都叫作context

    @Override

    public void refresh() throws BeansException, IllegalStateException {

        synchronized (this.startupShutdownMonitor) {

            // Prepare this context for refreshing.

            prepareRefresh();//一

            // Tell the subclass to refresh the internal bean factory.

            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();//二、

            // Prepare the bean factory for use in this context.

            prepareBeanFactory(beanFactory);//三、

            try {

                // Allows post-processing of the bean factory in context subclasses.

                postProcessBeanFactory(beanFactory);//四、

                // Invoke factory processors registered as beans in the context.

                invokeBeanFactoryPostProcessors(beanFactory);//五、

                // Register bean processors that intercept bean creation.

                registerBeanPostProcessors(beanFactory);//六、

                // Initialize message source for this context.

                initMessageSource();//七、

                // Initialize event multicaster for this context.

                initApplicationEventMulticaster();//八、

                // Initialize other special beans in specific context subclasses.

                onRefresh();//九、

                // Check for listener beans and register them.

                registerListeners();//十、

                // Instantiate all remaining (non-lazy-init) singletons.

                finishBeanFactoryInitialization(beanFactory);//十一、

                // Last step: publish corresponding event.

                finishRefresh();//十二、

            }

            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();//如果刷新失败那么就会将已经创建好的单例Bean销毁掉

                // Reset 'active' flag.

                cancelRefresh(ex);//重置context的活动状态

                // Propagate exception to caller.

                throw ex;//抛出异常

            }

            finally {

                // Reset common introspection caches in Spring's core, since we

                // might not ever need metadata for singleton beans anymore...

                resetCommonCaches();//重置的Spring内核的缓存。因为可能不再需要metadata给单例Bean了。

            }

        }

    }

这个方法的每一行代码都很重要。已经在代码中标上序号，下面会一句一句来解释。

一、prePareRefresh()

　　①、这个方法设置context的启动日期。

　　②、设置context当前的状态，是活动状态还是关闭状态。

　　③、初始化context environment（上下文环境）中的占位符属性来源。

　　④、验证所有必需的属性。

二、ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

　　让这个类（AbstractApplicationContext）的子类刷新内部bean工厂。实际上就是重新创建一个bean工厂。

obtainFreshBeanFactory()方法的代码如下：

    /**

     * Tell the subclass to refresh the internal bean factory.

     * @return the fresh BeanFactory instance

     * @see #refreshBeanFactory()

     * @see #getBeanFactory()

     */

    protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {

        refreshBeanFactory();//真正的刷新bean工厂。

        ConfigurableListableBeanFactory beanFactory = getBeanFactory();

        if (logger.isDebugEnabled()) {

            logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);

        }

        return beanFactory;

    }

上述代码中标红的refreshBeanFactory()最重要，其具体代码如下：

    /**

     * This implementation performs an actual refresh of this context's underlying

     * bean factory, shutting down the previous bean factory (if any) and

     * initializing a fresh bean factory for the next phase of the context's lifecycle.

     */

    @Override

    protected final void refreshBeanFactory() throws BeansException {

        if (hasBeanFactory()) {//如果已经存在一个bean工厂那么就将其销毁，关闭。

            destroyBeans();

            closeBeanFactory();

        }

        try {

            DefaultListableBeanFactory beanFactory = createBeanFactory();//新建一个Bean工厂。

            beanFactory.setSerializationId(getId());

            customizeBeanFactory(beanFactory);//自定义bean工厂。

            loadBeanDefinitions(beanFactory);//加载BeanDefinition

            synchronized (this.beanFactoryMonitor) {

                this.beanFactory = beanFactory;//将创建好的bean工厂的引用交给的context来管理。

            }

        }

        catch (IOException ex) {//加载bean定义资源的时候可能会抛出异常。

            throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);

        }

    }

三、prepareBeanFactory(beanFactory);

上一步已经把工厂建好了，但是还不能投入使用，因为工厂里什么都没有，还需要配置一些东西。看看这个方法的注释

他说配置这个工厂的标准环境，比如context的类加载器和后处理器。看看具体有哪些，反正很多。都是往BeanFactory中add什么东西，或者Register什么东西。反正在一系列的add和Register后工厂的功能会越来越健全。

直接贴代码：prepareBeanFactory(ConfigurableListableBeanFactory beanFactory)

    /**

     * Configure the factory's standard context characteristics,

     * such as the context's ClassLoader and post-processors.

     * @param beanFactory the BeanFactory to configure

     */

    protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {

        // Tell the internal bean factory to use the context's class loader etc.

        beanFactory.setBeanClassLoader(getClassLoader());

        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 interface not registered as resolvable type in a plain factory.

        // MessageSource registered (and found for autowiring) as a bean.

        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.

        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.

        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());

        }

    }

四、postProcessBeanFactory(beanFactory);

上面对bean工厂进行了许多配置，现在需要对bean工厂进行一些处理。

　　①、添加一个ServletContextAwareProcessor到bean工厂中。

　　②、在bean工厂自动装配的时候忽略一些接口。如：ServletContextAware、ServletConfigAware

　　③、注册WEB应用特定的域（scope）到bean工厂中，以便WebApplicationContext可以使用它们。比如"request", "session", "globalSession", "application"，

　　④、注册WEB应用特定的Environment bean到bean工厂中，以便WebApplicationContext可以使用它们。如："contextParameters", "contextAttributes"

下面是这个方法的代码：

/**

     * Register request/session scopes, a {@link ServletContextAwareProcessor}, etc.

     */

    @Override

    protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {

        beanFactory.addBeanPostProcessor(new ServletContextAwareProcessor(this.servletContext, this.servletConfig));

        beanFactory.ignoreDependencyInterface(ServletContextAware.class);

        beanFactory.ignoreDependencyInterface(ServletConfigAware.class);

        WebApplicationContextUtils.registerWebApplicationScopes(beanFactory, this.servletContext);

        WebApplicationContextUtils.registerEnvironmentBeans(beanFactory, this.servletContext, this.servletConfig);

    }

五、invokeBeanFactoryPostProcessors(beanFactory)

这一步也是对bean工厂进行一些处理。这一步主要是调用所有的bean工厂处理器（BeanFactoryPostProcessor）对bean工厂进行一些处理。这个方法必须在所有的singleton初始化之前调用。

    /**

     * Instantiate and invoke all registered BeanFactoryPostProcessor beans,

     * respecting explicit order if given.

     * <p>Must be called before singleton instantiation.

     */

    protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {

        PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());//这个行代码重要

        // 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()));

        }

    }

上面标红的代码的具体实现如下，代码非常多。主要是在这里面调用了所有的BeanFactoryPostProcessor。

    public static void invokeBeanFactoryPostProcessors(

            ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {

        // Invoke BeanDefinitionRegistryPostProcessors first, if any.

        Set<String> processedBeans = new HashSet<String>();

        if (beanFactory instanceof BeanDefinitionRegistry) {

            BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;

            List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>();

            List<BeanDefinitionRegistryPostProcessor> registryPostProcessors =

                    new LinkedList<BeanDefinitionRegistryPostProcessor>();

            for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {

                if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {

                    BeanDefinitionRegistryPostProcessor registryPostProcessor =

                            (BeanDefinitionRegistryPostProcessor) postProcessor;

                    registryPostProcessor.postProcessBeanDefinitionRegistry(registry);

                    registryPostProcessors.add(registryPostProcessor);

                }

                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.

            String[] postProcessorNames =

                    beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);

            // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.

            List<BeanDefinitionRegistryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();

            for (String ppName : postProcessorNames) {

                if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {

                    priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));

                    processedBeans.add(ppName);

                }

            }

            sortPostProcessors(beanFactory, priorityOrderedPostProcessors);

            registryPostProcessors.addAll(priorityOrderedPostProcessors);

            invokeBeanDefinitionRegistryPostProcessors(priorityOrderedPostProcessors, registry);

            // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.

            postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);

            List<BeanDefinitionRegistryPostProcessor> orderedPostProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();

            for (String ppName : postProcessorNames) {

                if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {

                    orderedPostProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));

                    processedBeans.add(ppName);

                }

            }

            sortPostProcessors(beanFactory, orderedPostProcessors);

            registryPostProcessors.addAll(orderedPostProcessors);

            invokeBeanDefinitionRegistryPostProcessors(orderedPostProcessors, registry);

            // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.

            boolean reiterate = true;

            while (reiterate) {

                reiterate = false;

                postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);

                for (String ppName : postProcessorNames) {

                    if (!processedBeans.contains(ppName)) {

                        BeanDefinitionRegistryPostProcessor pp = beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class);

                        registryPostProcessors.add(pp);

                        processedBeans.add(ppName);

                        pp.postProcessBeanDefinitionRegistry(registry);

                        reiterate = true;

                    }

                }

            }

            // Now, invoke the postProcessBeanFactory callback of all processors handled so far.

            invokeBeanFactoryPostProcessors(registryPostProcessors, 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!

        String[] postProcessorNames =

                beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);

        // Separate between BeanFactoryPostProcessors that implement PriorityOrdered,

        // Ordered, and the rest.

        List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();

        List<String> orderedPostProcessorNames = new ArrayList<String>();

        List<String> nonOrderedPostProcessorNames = new ArrayList<String>();

        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(beanFactory, priorityOrderedPostProcessors);

        invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);

        // Next, invoke the BeanFactoryPostProcessors that implement Ordered.

        List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();

        for (String postProcessorName : orderedPostProcessorNames) {

            orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));

        }

        sortPostProcessors(beanFactory, orderedPostProcessors);

        invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

        // Finally, invoke all other BeanFactoryPostProcessors.

        List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>();

        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();

    }

六、registerBeanPostProcessors(beanFactory);

注册用来拦截bean创建的BeanPostProcessor bean.这个方法需要在所有的application bean初始化之前调用。把这个注册的任务委托给了PostProcessorRegistrationDelegate来完成。

    public static void registerBeanPostProcessors(

            ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {

        String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);

        // Register BeanPostProcessorChecker that logs an info message when

        // a bean is created during BeanPostProcessor instantiation, i.e. when

        // a bean is not eligible for getting processed by all BeanPostProcessors.

        int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;

        beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

        // Separate between BeanPostProcessors that implement PriorityOrdered,

        // Ordered, and the rest.

        List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();

        List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();

        List<String> orderedPostProcessorNames = new ArrayList<String>();

        List<String> nonOrderedPostProcessorNames = new ArrayList<String>();

        for (String ppName : postProcessorNames) {

            if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {

                BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);

                priorityOrderedPostProcessors.add(pp);

                if (pp instanceof MergedBeanDefinitionPostProcessor) {

                    internalPostProcessors.add(pp);

                }

            }

            else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {

                orderedPostProcessorNames.add(ppName);

            }

            else {

                nonOrderedPostProcessorNames.add(ppName);

            }

        }

        // First, register the BeanPostProcessors that implement PriorityOrdered.首先，注册实现了PriorityOrdered接口的BeanPostProcessor

        sortPostProcessors(beanFactory, priorityOrderedPostProcessors);

        registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

        // Next, register the BeanPostProcessors that implement Ordered.然后注册实现了Ordered接口的BeanPostProcessor

        List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();

        for (String ppName : orderedPostProcessorNames) {

            BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);

            orderedPostProcessors.add(pp);

            if (pp instanceof MergedBeanDefinitionPostProcessor) {

                internalPostProcessors.add(pp);

            }

        }

        sortPostProcessors(beanFactory, orderedPostProcessors);

        registerBeanPostProcessors(beanFactory, orderedPostProcessors);

        // Now, register all regular BeanPostProcessors.注册所有常规的的BeanPostProcessor

        List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>();

        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.最后重新注册所有的内部BeanPostProcessor

        sortPostProcessors(beanFactory, internalPostProcessors);

        registerBeanPostProcessors(beanFactory, internalPostProcessors);

        // Re-register post-processor for detecting inner beans as ApplicationListeners,重新注册用来自动探测内部ApplicationListener的post-processor，这样可以将他们移到处理器链条的末尾。

        // moving it to the end of the processor chain (for picking up proxies etc).

        beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));

    }

七、initMessageSource();

初始化MessageSource接口的一个实现类。这个接口提供了消息处理功能。主要用于国际化/i18n。

八、initApplicationEventMulticaster();

为这个context初始化一个事件广播器（ApplicationEventMulticaster）。

AbstractApplicationContext中有一个常量：

    /**

     * Name of the ApplicationEventMulticaster bean in the factory.

     * If none is supplied, a default SimpleApplicationEventMulticaster is used.

     * @see org.springframework.context.event.ApplicationEventMulticaster

     * @see org.springframework.context.event.SimpleApplicationEventMulticaster

     */

    public static final String APPLICATION_EVENT_MULTICASTER_BEAN_NAME = "applicationEventMulticaster";

这个常量就是的ApplicationEventMulticaster bean的名字。程序首先会检查bean工厂中是否有bean的名字和这个常量相同的，如果没有则说明没有那么就使用默认的ApplicationEventMulticaster 的实现：SimpleApplicationEventMulticaster

    /**

     * Initialize the ApplicationEventMulticaster.

     * Uses SimpleApplicationEventMulticaster if none defined in the context.

     * @see org.springframework.context.event.SimpleApplicationEventMulticaster

     */

    protected void initApplicationEventMulticaster() {

        ConfigurableListableBeanFactory beanFactory = getBeanFactory();

        if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {检查是否给context配了一个ApplicationEventMulticaster实现类

            this.applicationEventMulticaster =

                    beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);

            if (logger.isDebugEnabled()) {

                logger.debug("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");

            }

        }

        else {//如果没有，就是用默认的实现类 SimpleApplicationEventMulticaster

            this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);

            beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);

            if (logger.isDebugEnabled()) {

                logger.debug("Unable to locate ApplicationEventMulticaster with name '" +

                        APPLICATION_EVENT_MULTICASTER_BEAN_NAME +

                        "': using default [" + this.applicationEventMulticaster + "]");

            }

        }

    }

九、onRefresh();

在AbstractApplicationContext的子类中初始化其他特殊的bean。其实就是初始化ThemeSource接口的实例。这个方法需要在所有单例bean初始化之前调用。

十、registerListeners();

注册应用的监听器。就是注册实现了ApplicationListener接口的监听器bean，这些监听器是注册到ApplicationEventMulticaster中的。这不会影响到其它监听器bean。在注册完以后，还会将其前期的事件发布给相匹配的监听器。

    /**

     * Add beans that implement ApplicationListener as listeners.

     * Doesn't affect other listeners, which can be added without being beans.

     */

    protected void registerListeners() {

        // Register statically specified listeners first.

        for (ApplicationListener<?> listener : getApplicationListeners()) {

            getApplicationEventMulticaster().addApplicationListener(listener);

        }

        // Do not initialize FactoryBeans here: We need to leave all regular beans

        // uninitialized to let post-processors apply to them!

        String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);

        for (String listenerBeanName : listenerBeanNames) {

            getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);

        }

        // Publish early application events now that we finally have a multicaster...至此，已经完成将监听器注册到ApplicationEventMulticaster中，下面将发布前期的事件给监听器。

        Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;

        this.earlyApplicationEvents = null;

        if (earlyEventsToProcess != null) {

            for (ApplicationEvent earlyEvent : earlyEventsToProcess) {

                getApplicationEventMulticaster().multicastEvent(earlyEvent);

            }

        }

    }

十一、finishBeanFactoryInitialization(beanFactory);

完成bean工厂的初始化工作。这一步非常复杂，也非常重要，涉及到了bean的创建。第二步中只是完成了BeanDefinition的定义、解析、处理、注册。但是还没有初始化bean实例。这一步将初始化所有非懒加载的单例bean。这一步将会重新在一篇新的笔记中介绍。

十二、finishRefresh();

完成context的刷新。主要是调用LifecycleProcessor的onRefresh()方法，并且发布事件（ContextRefreshedEvent）。

巴特西

Spring AbstractApplicationContext抽象类的refresh()方法--笔记

最新文章

热门文章