@Overridepublicvoidrefresh() throwsBeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
StartupStepcontextRefresh=this.applicationStartup.start("spring.context.refresh");
// Prepare this context for refreshing. 准备刷新上下文prepareRefresh();
// Tell the subclass to refresh the internal bean factory. 告诉子类刷新内部bean工厂ConfigurableListableBeanFactorybeanFactory=obtainFreshBeanFactory();
// Prepare the bean factory for use in this context. 准备bean工厂以用于此上下文prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses. 允许在上下文子类中对bean工厂进行后置处理postProcessBeanFactory(beanFactory);
StartupStepbeanPostProcess=this.applicationStartup.start("spring.context.beans.post-process");
// Invoke factory processors registered as beans in the context. 调用上下文中注册为bean的工厂处理器invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.  注册拦截器bean创建的bean处理器registerBeanPostProcessors(beanFactory);
beanPostProcess.end();
// Initialize message source for this context. 初始化此上下文的消息源initMessageSource();
// Initialize event multicaster for this context. 为此上下文初始化事件多播initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses. 初始化特定上下文子类中的其他特殊beanonRefresh();
// Check for listener beans and register them. 检查监听器bean并注册registerListeners();
// Instantiate all remaining (non-lazy-init) singletons. 实例化所有剩余的（非懒惰初始化）单例finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event. 最后一步：发布相应的事件finishRefresh();
        }
catch (BeansExceptionex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - "+"cancelling refresh attempt: "+ex);
            }
// Destroy already created singletons to avoid dangling resources. 销毁已创建的单例以避免悬空资源destroyBeans();
// Reset 'active' flag. 重置active标志cancelRefresh(ex);
// Propagate exception to caller. 将异常传播到调用方throwex;
        }
finally {
// Reset common introspection caches in Spring's core, since we// might not ever need metadata for singleton beans anymore...//重置Spring核心中的公共内省缓存，因为我们可能不再需要单例bean的元数据resetCommonCaches();
contextRefresh.end();
        }
    }
}

/*** Prepare this context for refreshing, setting its startup date and* active flag as well as performing any initialization of property sources.*/protectedvoidprepareRefresh() {
// Switch to active. 切换到激活this.startupDate=System.currentTimeMillis();
this.closed.set(false);
this.active.set(true);
if (logger.isDebugEnabled()) {
if (logger.isTraceEnabled()) {
logger.trace("Refreshing "+this);
        }
else {
logger.debug("Refreshing "+getDisplayName());
        }
    }
// Initialize any placeholder property sources in the context environment. 初始化上下文环境中的任何占位符属性源initPropertySources();
// Validate that all properties marked as required are resolvable:验证标记为需要的所有属性是否可解析// see ConfigurablePropertyResolver#setRequiredProperties 主要看ConfigurablePropertyResolver#setRequiredPropertiesgetEnvironment().validateRequiredProperties();
// Store pre-refresh ApplicationListeners... 预刷新应用监听器if (this.earlyApplicationListeners==null) {
this.earlyApplicationListeners=newLinkedHashSet<>(this.applicationListeners);
    }
else {
// Reset local application listeners to pre-refresh state. 重置应用监听器为预刷新状态this.applicationListeners.clear();
this.applicationListeners.addAll(this.earlyApplicationListeners);
    }
// Allow for the collection of early ApplicationEvents, 允许收集早期的应用事件在multicaster可用后一次性发布// to be published once the multicaster is available...this.earlyApplicationEvents=newLinkedHashSet<>();
}