C# 远程传输File文件

        /// <summary>
        /// 向论坛传图片文件
        /// </summary>
        /// <param name="filePath"></param>
        /// <param name="categoryid"></param>
        private void SendImageToTaobao(string url, string filePath, string username) {
            try {
                // 设置参数
                HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
                CookieContainer cookieContainer = new CookieContainer();
                request.CookieContainer = cookieContainer;
                request.AllowAutoRedirect = true;
                request.Timeout = 3000;
                request.Method = "POST";
                string boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线
                request.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;
                byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");
                byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");

                //头部信息  参数 
                StringBuilder sbText = new StringBuilder(string.Format("Content-Disposition:form-data;name=\"username\"\r\nContent-Type:text/plain\r\n\r\n{0}", username));
                byte[] postTextBytes = Encoding.UTF8.GetBytes(sbText.ToString());

                string fileName = "logo.jpg";
                //头部信息  文件流 
                StringBuilder sbHeader = new StringBuilder(string.Format("Content-Disposition:form-data;name=\"aws_upload_file\";filename=\"{0}\"\r\nContent-Type:application/octet-stream\r\n\r\n", fileName));
                byte[] postHeaderBytes = Encoding.UTF8.GetBytes(sbHeader.ToString());

                FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
                byte[] bArr = new byte[fs.Length];
                fs.Read(bArr, 0, bArr.Length);
                fs.Close();

                Stream postStream = request.GetRequestStream();
                postStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
                postStream.Write(postTextBytes, 0, postTextBytes.Length);

                postStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
                postStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);
                postStream.Write(bArr, 0, bArr.Length);
                postStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);
                postStream.Close();

                //发送请求并获取相应回应数据
                HttpWebResponse response = request.GetResponse() as HttpWebResponse;
                //直到request.GetResponse()程序才开始向目标网页发送Post请求
                Stream instream = response.GetResponseStream();
                StreamReader sr = new StreamReader(instream, Encoding.UTF8);
                //返回结果网页（html）代码
                string content = sr.ReadToEnd();
            } catch (Exception ex) {
                var data = ex.Message;
            }
        }