internal string GetWebContent(Uri uri)        {            string tempCode = null;            string error = null;            int time = 0;            HttpWebResponse response = null;            HttpWebRequest request = null;            do                                                               //访问失败时重新访问，最多重新访问4次            {                WebProxy proxy = new WebProxy("代理网站", false);                proxy.Credentials = new NetworkCredential(@"用户名", "密码", "");                request = HttpWebRequest.Create(uri.AbsoluteUri) as HttpWebRequest;                Thread.Sleep(30);                request.AllowAutoRedirect = true;                request.Proxy = proxy;                                          //使用了代理                int a = 0;                time += 1;                error = null;                try                {                    DateTime now = DateTime.Now;                    response = request.GetResponse() as HttpWebResponse;                    TimeSpan t = DateTime.Now - now;                }                catch (Exception ex)                {                    tempCode = ex.Message;                    error = ex.Message;                }            } while (error != null && time < 4);            System.IO.Stream resStream = null;            StreamReader sr = null;            try            {                resStream = response.GetResponseStream();                sr = new StreamReader(resStream, Encoding.UTF8);                tempCode = sr.ReadToEnd();                response.Close();                resStream.Close();                sr.Close();            }            catch (Exception e)            {}                        return tempCode;        }