1、文件上传 

/// <summary>
        /// WebClient上传文件至服务器
        /// </summary>
        /// <param name="fileNamePath">文件名，全路径格式</param>
        /// <param name="uriString">服务器文件夹路径</param>
        private void UpLoadFile(string fileNamePath, string uriString)
        {
            string fileName = fileNamePath.Substring(fileNamePath.LastIndexOf("\\") + 1);
            NewFileName = DateTime.Now.ToString("yyMMddhhmmss") + DateTime.Now.Millisecond.ToString() + fileNamePath.Substring(fileNamePath.LastIndexOf("."));
            string fileNameExt = fileName.Substring(fileName.LastIndexOf(".") + 1);
            if (uriString.EndsWith("/") == false) uriString = uriString + "/";
            uriString = uriString + NewFileName;
            UpFileName = NewFileName;
            /**/
            /// 创建WebClient实例
            WebClient myWebClient = new WebClient();
            myWebClient.Credentials = CredentialCache.DefaultCredentials;
            // 要上传的文件
            FileStream fs = new FileStream(fileNamePath, FileMode.Open, FileAccess.Read);
            //FileStream fs = OpenFile();
            BinaryReader r = new BinaryReader(fs);
            try
            {
                //使用UploadFile方法可以用下面的格式
                //myWebClient.UploadFile(uriString,"PUT",fileNamePath);
                byte[] postArray = r.ReadBytes((int)fs.Length);
                Stream postStream = myWebClient.OpenWrite(uriString, "PUT");
                if (postStream.CanWrite)
                {
                    postStream.Write(postArray, 0, postArray.Length);
                }
                else
                {
                    MessageBox.Show("文件目前不可写！");
                }
                postStream.Close();
            }
            catch
            {
                MessageBox.Show("文件上传失败，请稍候重试~");
            }
        }

2、文件下载

  string filePath = System.AppDomain.CurrentDomain.BaseDirectory.ToString()+"ProgramOut.xml";//路径 
                WebClient client = new WebClient();
                string fileName = filePath.Substring(filePath.LastIndexOf("\\") + 1); //被下载的文件名
                SaveFileDialog saveFileDialog = new SaveFileDialog();
                saveFileDialog.Filter = "XML文件|*.xml";
                saveFileDialog.FilterIndex = 2;
                saveFileDialog.RestoreDirectory = true;
                if (saveFileDialog.ShowDialog() == DialogResult.OK)
                {
                    string fName = saveFileDialog.FileName;
                    string Path = fName; //另存为的绝对路径＋文件名
                    try
                    {
                        WebRequest myre = WebRequest.Create(Path);
                    }
                    catch
                    {
                        MessageBox.Show("文件下载失败", "Error");
                    }
                    try
                    {
                        client.DownloadFile(filePath, Path);
                        MessageBox.Show("文件导出成功！！", "系统提示！", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                    catch
                    {
                        MessageBox.Show("文件下载失败", "Error");
                    }