SFTPHelper

public class SFTPHelper
    {
        #region 字段或属性

        private readonly SftpClient _sftp;

        /// <summary>
        /// SFTP连接状态
        /// </summary>
        public bool Connected
        {
            get
            {
                return _sftp.IsConnected;
            }
        }

        #endregion

        #region 构造函数

        /// <summary>
        /// 构造1
        /// </summary>
        /// <param name="ip">IP</param>
        /// <param name="port">端口</param>
        /// <param name="user">用户名</param>
        /// <param name="pwd">密码</param>
        public SFTPHelper(string ip, string port, string user, string pwd)
        {
            _sftp = new SftpClient(ip, Int32.Parse(port), user, pwd);
        }

        /// <summary>
        /// 构造2
        /// </summary>
        /// <param name="host">服务器地址</param>
        /// <param name="user">用户名</param>
        /// <param name="pwd">密码</param>
        public SFTPHelper(string host, string user, string pwd)
        {
            _sftp = new SftpClient(host, user, pwd);
        }

        #endregion

        #region 连接SFTP

        /// <summary>
        /// 连接SFTP
        /// </summary>
        /// <returns>true成功</returns>
        private void Connect()
        {
            if (!Connected)
            {
                _sftp.Connect();
            }
        }

        #endregion

        #region 断开SFTP

        /// <summary>
        /// 断开SFTP
        /// </summary> 
        private void Disconnect()
        {
            if (_sftp != null && Connected)
            {
                _sftp.Disconnect();
            }
        }

        #endregion

        #region SFTP上传文件

        /// <summary>
        /// SFTP上传文件
        /// </summary>
        /// <param name="localPath">本地路径</param>
        /// <param name="remotePath">远程路径</param>
        public void UploadFile(string localPath, string remotePath)
        {
            using (var fileStream = File.OpenRead(localPath))
            {
                Connect();
                _sftp.UploadFile(fileStream, remotePath);
                Disconnect();
            }
        }

        #endregion

        #region SFTP下载文件

        /// <summary>
        /// SFTP下载文件
        /// </summary>
        /// <param name="remotePath">远程路径</param>
        /// <param name="localPath">本地路径</param>
        public void DownloadFile(string remotePath, string localPath)
        {
            Connect();
            var byt = _sftp.ReadAllBytes(remotePath);
            Disconnect();
            File.WriteAllBytes(localPath, byt);
        }

        #endregion
    }