Flex 监听浏览器关闭

在creationComplete的事件中，添加如下：

if(ExternalInterface.available)//外部接口是否可用
    {
     var js:String= "eval(\'window.onbeforeunload = onbeforeunloadHandler;"
      + "function onbeforeunloadHandler(){"
      + "var swfRef = document."
      + FlexGlobals.topLevelApplication.className + "||window."
      + FlexGlobals.topLevelApplication.className
      + ";" + "swfRef.windowCloseHandler();" + "}\')";
     flash.external.ExternalInterface.call(js);
    }
    //增加回调，当浏览器关闭，flex应用程序也关闭后，执行的函数
       ExternalInterface.addCallback('windowCloseHandler',externalWindowCloseHandler);

private function externalWindowCloseHandler():void
   {
    trace("后续清理");
   }