判断网络图片是否存在

try
        {
            string url = "http://wx.qlogo.cn/mmopen/g3MonUZtNHkdmzicIlibx6iaFqAc56vxLSUfpb6n5WKSYVY0ChQKkiaJSgQ1dZuTOgvLLrhJbERQQ4eMsv84eavHiaiceqxibJxCfHe/0";
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(url));
            ((HttpWebResponse)request.GetResponse()).Close();
            Response.Write("图片存在");
        }
        catch
        {
            Response.Write("图片不存在！");
        }