string path = openFileDialog1.FileName;

                WebClient wc = new WebClient();

                wc.Credentials = CredentialCache.DefaultCredentials;

                wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

                wc.QueryString["fname"] = openFileDialog1.SafeFileName;

                byte[] fileb = wc.UploadFile(new Uri(@"http://192.168.31.37:8977/FileHandler.ashx"), "POST", path);

                string res = Encoding.GetEncoding("gb2312").GetString(fileb);

                  //或者

                //wc.UploadFileAsync(new Uri(@"http://192.168.31.37:8977/FileHandler.ashx"), "POST", path);

                //wc.UploadFileCompleted += (s, es) =>

                //{

                //    MessageBox.Show(Encoding.GetEncoding("gb2312").GetString(es.Result));

                //};
        

 public class FileHandler : IHttpHandler

    {

        public void ProcessRequest(HttpContext context)

        {

            context.Response.ContentType = "text/plain";

            try

            {

            HttpFileCollection files = context.Request.Files;

            if (files.Count > )

            {

                files[].SaveAs(HttpContext.Current.Server.MapPath("files/" + context.Request.QueryString["fname"]));

                context.Response.Write("save success!");

            }

            else

                context.Response.Write("hello request!");

            }

            catch (Exception ex)

            {

                context.Response.Write("save error!" + ex.Message);

            }

        }

        public bool IsReusable

        {

            get

            {

                return false;

            }

        }

    }

  if (folderBrowserDialog1.ShowDialog() == DialogResult.OK)

            {

                string path = folderBrowserDialog1.SelectedPath;

                WebClient wc = new WebClient();

                //wc.Credentials = CredentialCache.DefaultCredentials;

                wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

                string fileUrl = @"http://192.168.31.37:8977/files/多用文本.txt";

                wc.DownloadFile(new Uri(fileUrl), string.Format(@"{0}\{1}", path, fileUrl.Substring(fileUrl.LastIndexOf('/') + )));

                //或者

                wc.DownloadFileCompleted += (s, es) =>

                 {

                     MessageBox.Show("下载成功!");

                 };

                wc.DownloadFileAsync(new Uri(fileUrl), string.Format(@"{0}\{1}", path, fileUrl.Substring(fileUrl.LastIndexOf('/') + )));

            }