Spring 源码之核心加载方法(1)

1. prepareRefresh

定位: org.springframework.context.support.AbstractApplicationContext#prepareRefresh

// 准备刷新，设置应用开启的时间还有active标志，并且执行一些属性源的初始化工作
protected void prepareRefresh() {
   // Switch to active.
   // 设置容器启动实现
   this.startupDate = System.currentTimeMillis();
   // 设置容器的关闭标志位
   this.closed.set(false);
   // 设置容器的开启标志位
   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placeholder属性, 默认未实现, 由子类实现
   initPropertySources();

   // Validate that all properties marked as required are resolvable:
   // see ConfigurablePropertyResolver#setRequiredProperties
   // 创建并获取环境对象，验证需要的属性文件是否都已经放入环境中
   getEnvironment().validateRequiredProperties();

   // Store pre-refresh ApplicationListeners...
   // 判断刷新前的应用程序监听器集合是否为空，如果为空，则将监听器添加到此集合中
   if (this.earlyApplicationListeners == null) {
      this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
   }
   else {
      // Reset local application listeners to pre-refresh state.
      // 如果不等于空，则清空集合元素对象
      this.applicationListeners.clear();
      this.applicationListeners.addAll(this.earlyApplicationListeners);
   }

   // Allow for the collection of early ApplicationEvents,
   // to be published once the multicaster is available...
   // 允许应用启动之前的事件，当多播器一旦可用的时候，可用立刻响应发布的事件。
   this.earlyApplicationEvents = new LinkedHashSet<>();
}