Spring启动流程核心步骤：10、 finishRefresh()

  1、清除上下文资源缓存（如扫描中的ASM元数据）

 2、初始化上下文的生命周期处理器，并刷新（找出Spring容器中实现了Lifecycle接口的bean并执行start()方法）。

 3、发布ContextRefreshedEvent事件告知对应的ApplicationListener进行响应的操作

protected void finishRefresh() {
   // Clear context-level resource caches (such as ASM metadata from scanning).
   //清理缓存信息 
   clearResourceCaches();


   // Initialize lifecycle processor for this context.
   //初始化LifecycleProcessor
   initLifecycleProcessor();


   // Propagate refresh to lifecycle processor first.
    //寻找实现Lifecycle接口的Bean进行处理，调用对应的Start方法
   getLifecycleProcessor().onRefresh();


   // Publish the final event.
    //发布事件  详见：Spring事件专栏
   publishEvent(new ContextRefreshedEvent(this));


   // Participate in LiveBeansView MBean, if active.
   LiveBeansView.registerApplicationContext(this);
}
//初始化LifecycleProcessor、如果容器中没有则采用默认的
protected void initLifecycleProcessor() {
   ConfigurableListableBeanFactory beanFactory = getBeanFactory();
   if (beanFactory.containsLocalBean(LIFECYCLE_PROCESSOR_BEAN_NAME)) {
      this.lifecycleProcessor =
            beanFactory.getBean(LIFECYCLE_PROCESSOR_BEAN_NAME, LifecycleProcessor.class);
   }else {
      DefaultLifecycleProcessor defaultProcessor = new DefaultLifecycleProcessor();
      defaultProcessor.setBeanFactory(beanFactory);
      this.lifecycleProcessor = defaultProcessor;
      beanFactory.registerSingleton(LIFECYCLE_PROCESSOR_BEAN_NAME, this.lifecycleProcessor);
   }
}

@Override
public void onRefresh() {
   startBeans(true);
   this.running = true;
}

private void startBeans(boolean autoStartupOnly) {
   Map<String, Lifecycle> lifecycleBeans = getLifecycleBeans(); //获取实现Lifecycle的接口的Bean
   Map<Integer, LifecycleGroup> phases = new HashMap<>();
   lifecycleBeans.forEach((beanName, bean) -> {
      if (!autoStartupOnly || (bean instanceof SmartLifecycle && ((SmartLifecycle) bean).isAutoStartup())) {
         int phase = getPhase(bean);
         LifecycleGroup group = phases.get(phase);
         if (group == null) {
            group = new LifecycleGroup(phase, this.timeoutPerShutdownPhase, lifecycleBeans, autoStartupOnly);
            phases.put(phase, group);
         }
         group.add(beanName, bean);
      }
   });
   if (!phases.isEmpty()) {
      List<Integer> keys = new ArrayList<>(phases.keySet());
      Collections.sort(keys);
      for (Integer key : keys) {
         phases.get(key).start(); //调用真正的逻辑
      }
   }
}