asp.net(c#)判断远程图片是否存在

代码如下:private int GetUrlError(string curl) { int num = 200; if(this.method==1) { HttpWebRequest request=(HttpWebRequest) WebRequest.Create(new Uri(curl)); ServicePointManager.Expect100Continue=false; try { ((HttpWebResponse)request.GetResponse()).Close(); } catch(WebException exception) { if(exceptio