public bool LinkWebUpload(string URL, string filePath, string filename)
        {
            bool flag = false;        //上传是否成功的标志
            int position = filePath.IndexOf(originFileName, 0);            //查找上传文件夹的起始目录名的位置，返回的是第一个匹配项的位置

            FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
            BinaryReader r = new BinaryReader(fs);
            string strBoundary = "----------" + DateTime.Now.Ticks.ToString("x");
            byte[] boundaryBytes = Encoding.ASCII.GetBytes("\r\n--" + strBoundary + "\r\n");  //请求头部信息
            StringBuilder sb = new StringBuilder();
            sb.Append("--");
            sb.Append(strBoundary);
            sb.Append("\r\n");
            sb.Append("Content-Disposition:form-data;name=\"");
            sb.Append("file");
            sb.Append("\";filename=\"");
            sb.Append(filename);
            sb.Append("\";");
            sb.Append("\r\n");
            sb.Append("Content-type:");
            sb.Append("application/octet-stream");
            sb.Append("\r\n");
            sb.Append("\r\n");
            string strPostHeader = sb.ToString();
            byte[] postHeaderBytes = Encoding.UTF8.GetBytes(strPostHeader);
            HttpWebRequest httpReq = (HttpWebRequest)WebRequest.Create(new Uri(URL));     //根据URL创建HttpWebRequestion对象
            httpReq.Method = "POST";       //采用post方法上传
            httpReq.AllowWriteStreamBuffering = false;    //对发送的数据不使用缓存
            httpReq.Timeout = 300000;               //设置获得响应的超时时间（300秒）
            httpReq.ContentType = "multipart/form-data;boundary=" + strBoundary;
            long length = fs.Length + postHeaderBytes.Length + boundaryBytes.Length;
            long fileLength = fs.Length;
            httpReq.ContentLength = length;
            try
            {

                int bufferLength = 4096;             //每次上传4K
                byte[] buffer = new byte[bufferLength];
                long offset = 0;              //已上传的字节数
                DateTime startTime = DateTime.Now;
                int size = r.Read(buffer, 0, bufferLength);
                Stream postStream = httpReq.GetRequestStream();
                postStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);
                while (size > 0)
                {
                    postStream.Write(buffer, 0, size);
                    offset += size;
                    size = r.Read(buffer, 0, bufferLength);
                }
                postStream.Write(boundaryBytes, 0, boundaryBytes.Length);     //添加尾部时间戳
                postStream.Close();
                WebResponse response = httpReq.GetResponse();         //获取服务器的响应
                Stream res = response.GetResponseStream();
                StreamReader sr = new StreamReader(res);              //读取服务器返回的数据
                string strRes = sr.ReadLine();
                res.Close();
                sr.Close();
                if (strRes == "Success")
                {
                    flag = true;
                }
                else if (strRes == "ERROR")
                {
                    flag = false;
                }
            }
            catch
            {
                flag = false;
            }
            finally
            {
                fs.Close();
                r.Close();
            }

            return flag;

        }