AS3 Post method analysis of crawling pages and reading progress bars

System.useCodePage=true;
varvariables:URLVariables=newURLVariables();
variables.userName="Kakera";
variables.password="********";
varrequest:URLRequest=newURLRequest("http://www.baidu.com");
request.data=variables;
request.method=URLRequestMethod.POST;
varloader:URLLoader=newURLLoader();
loader.dataFormat=URLLoaderDataFormat.TEXT;
loader.addEventListener(Event.COMPLETE,loader_complete);
loader.addEventListener(Event.OPEN,loader_open);
loader.addEventListener(HTTPStatusEvent.HTTP_STATUS,loader_httpStatus);
loader.addEventListener(ProgressEvent.PROGRESS,loader_progress);
loader.addEventListener(SecurityErrorEvent.SECURITY_ERROR,loader_security);
loader.addEventListener(IOErrorEvent.IO_ERROR,loader_ioError);
loader.load(request);
functionloader_complete(e:Event):void{
  trace("Event.COMPLETE");
  trace("目标文件的原始数据(纯文本):\n"+loader.data);
}
functionloader_open(e:Event):void{
  trace("Event.OPEN");trace("读取了的字节:"+loader.bytesLoaded);
}
functionloader_httpStatus(e:HTTPStatusEvent):void{
  trace("HTTPStatusEvent.HTTP_STATUS");
  trace("HTTP状态代码:"+e.status);
}
functionloader_progress(e:ProgressEvent):void{
  trace("ProgressEvent.PROGRESS");
  trace("读取了的字节:"+loader.bytesLoaded);
  trace("文件总字节:"+loader.bytesTotal);
}
functionloader_security(e:SecurityErrorEvent):void{
  trace("SecurityErrorEvent.SECURITY_ERROR");
}
functionloader_ioError(e:IOErrorEvent):void{
  trace("IOErrorEvent.IO_ERROR");
}