MemoryStream StreamToMemoryStream(Stream instream)        {            MemoryStream outstream = new MemoryStream();            const int bufferLen = 4096;            byte[] buffer = new byte[bufferLen];            int count = 0;            while ((count = instream.Read(buffer, 0, bufferLen)) > 0)            {                outstream.Write(buffer, 0, count);            }            return outstream;        }

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(filePath);                        request.Method = "GET";                        using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)                        {                            if (response.StatusCode == HttpStatusCode.OK)                            {                                Stream rs = response.GetResponseStream();//网络流转换为内存流                                var ms = StreamToMemoryStream(rs);                                ms.Seek(0, SeekOrigin.Begin); int buffsize = (int)ms.Length; //rs.Length 此流不支持查找,先转为MemoryStream                                byte[] bytes = new byte[buffsize];                                ms.Read(bytes, 0, buffsize);                                ms.Flush(); ms.Close();                                rs.Flush(); rs.Close();//以文件流的方式下载                                Response.Charset = "utf-8";                                Response.ContentEncoding = System.Text.Encoding.GetEncoding("utf-8");                                Response.ContentType = "application/octet-stream";                                if (HttpContext.Current.Request.UserAgent.ToUpper().Contains("MSIE") ||                                    HttpContext.Current.Request.UserAgent.ToUpper().Contains("TRIDENT") ||                                    HttpContext.Current.Request.UserAgent.ToUpper().Contains("EDGE"))                                {                                    name = HttpUtility.UrlEncode(name, System.Text.Encoding.UTF8);                                }                                else                                {                                    name = name.Replace(" ", "_");                                }                                //fileName = HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8);                                Response.AddHeader("Content-Disposition", "attachment;   filename=" + name);                                Response.BinaryWrite(bytes);                                Response.Flush();                                Response.End();                            }                        }

private string GetContractPathRules(string id, string name) {            string url = ConfigurationManager.AppSettings["ContractUrl"];            url = url.TrimEnd('/') + "/";            return Path.Combine(url, Path.Combine(id + "/", name));        }//例如：http://x.x.x.x:8088/xxx/xxx.pdf