public  class FTPClient    {      private  string ftpServerIP="";//下载的ip      private string ftpUserID="";  //用户名      private string ftpPassword=""; //密码      //带参的构造函数      public FTPClient(string ftpServerIP, string ftpUserID, string ftpPassword)       {        this.ftpPassword=ftpPassword;        this.ftpUserID = ftpUserID;        this.ftpServerIP = ftpServerIP;      }      /// 
      /// 下载的方法      /// 
      /// 要下载的路径      /// 要下载的文件名，如果为空，则代表文件下的全部文件      public  void Download(string filePath, string fileName)      {          FtpWebRequest reqFTP;          try          {              FileStream outputStream = new FileStream(filePath + "\\" + fileName, FileMode.Create);    //文件流暑促文件              reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + ftpServerIP + "/" + fileName)); //创建ftpWebRequest              reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;           //ftp的方法，上传还是下载              reqFTP.UseBinary = true;              //是否使用二进制              reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);   //输入用户名和密码              FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();              Stream ftpStream = response.GetResponseStream();  //获取文件流              long cl = response.ContentLength; //文件流的长度              int bufferSize = 2048;              int readCount;              byte[] buffer = new byte[bufferSize]; //字节转换              readCount = ftpStream.Read(buffer, 0, bufferSize);                        while (readCount > 0)                  {                      outputStream.Write(buffer, 0, readCount);                      readCount = ftpStream.Read(buffer, 0, bufferSize); //读取文件                  }                            ftpStream.Close();              outputStream.Close();              response.Close();              System.GC.Collect();          }          catch (Exception ex)          {            //  MessageBox.Show(ex.Message);          }      }    }

上面是FTp的后台服务端，下面是应用客户端：

ftpServerIP = "192.168.2.211/Test/ssl/Image";            ftpUserID = "123456";            ftpPassword = "123456";            FTPClient ftpClient = new FTPClient(ftpServerIP, ftpUserID, ftpPassword);            ftpClient.Download(@"C:\picture", "3201.png");

客户端可以输入ip,用户名，密码，要下载的路径或者有下载的文件，就可以执行了。如果下载文件为空，则代表下载ip底下的所有文件。