asp教程.net c#利用FtpWebRequest上传下载文件实例
根据uri创建FtpWebRequest对象
  FtpWebRequest ftpReq = (FtpWebRequest)FtpWebRequest.Create(new Uri(strUri));
  // ftp用户名和密码
  ftpReq.Credentials = new NetworkCredential("用户名", "密码");
  // 指定执行什么命令
  ftpReq.Method = WebRequestMethods.Ftp.UploadFile;
  //成功执行一个命令后连接被关闭
  ftpReq.KeepAlive = false;
  //指定数据传输类型为二进制
  ftpReq.UseBinary = true;
  //上传文件时通知服务器文件的大小  
  ftpReq.ContentLength = fi.Length;
  // 缓冲大小设置为2kb  
  int buffLength = 2048;  
  byte[] buff = new byte[buffLength];

  int contentLen;
   

  try
  {
  //打开一个文件流去读上传的文件
  FileStream fs = fi.OpenRead();
  //把上传的文件写入流
  Stream strm = ftpReq.GetRequestStream();

  //每次读文件流的2kb  
 

contentLen = fs.Read(buff, 0, buffLength);
   
  while (contentLen != 0) // 流内容没有结束
  {
  // 把内容从file stream 写入 upload stream 
  strm.Write(buff, 0, contentLen);  
  contentLen = fs.Read(buff, 0, buffLength);  
  }
  strm.Close();
  fs.Close();
  }
  catch (Exception e)
  {
   
  }

  '方法二
 

  FileInfo file = new FileInfo("G:/www.111cn.net/室内设计01.jpg");
                if (file.Exists)
                {
                    Response.Clear();
                    Response.AddHeader("Content-Disposition", "attachment;filename=" + Server.UrlEncode(file.Name));
                    Response.AddHeader("Content-Length", file.Length.ToString());
                    Response.ContentType = "application/octet-stream";
                    Response.Filter.Close();
                    Response.WriteFile(file.FullName);
                    Response.End();
                }