使用SSH.NET，上传文件（C#，SFTP）

            OpenFileDialog dialog = new OpenFileDialog();
            dialog.Multiselect = false;//该值确定是否可以选择多个文件
            dialog.Title = "请选择*.csv文档";
            //筛选文件类型
            dialog.Filter = "所有文件(*.csv)|*.csv";
            if (dialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                string a=System.IO.Path.GetFileName(dialog.FileName);//得到文件名
                
                string b=System.IO.Path.GetDirectoryName(dialog.FileName);//得到路径

                string c=System.IO.Path.GetFullPath(dialog.FileName);//绝对路径

                string d = System.IO.Path.GetExtension(dialog.FileName);//文件扩展名

                string ew = System.IO.Path.GetFileNameWithoutExtension(dialog.FileName); //文件名没有扩展名

                string f = System.IO.Path.GetFileName(dialog.FileName);//得到文件

                string g = System.IO.Path.GetDirectoryName(dialog.FileName);

                textBox1.Text = dialog.FileName;
            }

            FolderBrowserDialog P_File_Folder = new FolderBrowserDialog();
            if (P_File_Folder.ShowDialog() == DialogResult.OK)
            {
                textBox2.Text = P_File_Folder.SelectedPath;
            }

            //实例化文件操作类（详情看备注一）
            FileInfo f = new FileInfo(route);
            //	FullName只读属性，获取文件的名称
            String uploadfile = f.FullName;
    
            //1.SFTP建立连接
            //参数  1.主机地址  2.端口  3.用户名  4.密码
            var client = new SftpClient(SFTP_IP, Int32.Parse(SFTP_port), SFTP_username, SFTP_password);
            //开启连接
            client.Connect();
            //判断连接是否成功
            if (client.IsConnected)
            {
                //连接成功
                Console.WriteLine("I AM CONNECTED");
            }
            var fileStream = new FileStream(uploadfile, FileMode.Open);
            if (fileStream != null)
            {
                Console.WriteLine("YOU ARE NOT NULL");
            }            
            client.BufferSize = 4 * 1024;  
            
           //上传方法  参数 1.Data input stream.  2.上传至文件地址+文件名 3.回调地址 
           //方法说过详情看备注二
            client.UploadFile(fileStream,  SFTP_catalog + f.Name, null);
            //关闭连接
            client.Disconnect();
            //释放
            client.Dispose();

/// 

        /// 选择要上传的文件
        /// 
        /// 
        /// 
        private void button1_Click(object sender, EventArgs e)
        {
            //命名空间System.Configuration中不存在类型或命名空间名称ConfigurationManager
            //手动添加这个程序集的引用，在项目右键添加引用选择System.Configuration即可.
            String SFTP_IP = System.Configuration.ConfigurationManager.AppSettings["SFTP_IP"];
            String SFTP_port = System.Configuration.ConfigurationManager.AppSettings["SFTP_port"];
            String SFTP_username = System.Configuration.ConfigurationManager.AppSettings["SFTP_username"];
            String SFTP_password = System.Configuration.ConfigurationManager.AppSettings["SFTP_password"];
            String SFTP_catalog = System.Configuration.ConfigurationManager.AppSettings["SFTP_catalog"];

            String route = "";
            String name = "";
            OpenFileDialog dialog = new OpenFileDialog();
            dialog.Multiselect = false;//该值确定是否可以选择多个文件
            dialog.Title = "请选择电子文档excel";
            dialog.Filter = "所有文件(*.csv)|*.csv";
            if (dialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                name = System.IO.Path.GetFileName(dialog.FileName);//得到文件名
                route = System.IO.Path.GetFullPath(dialog.FileName);//绝对路径
                textBox1.Text = name;
            }
            FileInfo f = new FileInfo(route);
            String uploadfile = f.FullName;

            //1.SFTP建立连接           
            var client = new SftpClient(SFTP_IP, Int32.Parse(SFTP_port), SFTP_username, SFTP_password);        
            client.Connect();
            if (client.IsConnected)
            {
                Console.WriteLine("I AM CONNECTED");
            }
            var fileStream = new FileStream(uploadfile, FileMode.Open);
            if (fileStream != null)
            {
                Console.WriteLine("YOU ARE NOT NULL");
            }            
            client.BufferSize = 4 * 1024;              
            client.UploadFile(fileStream,  SFTP_catalog + f.Name, null);
            client.Disconnect();
            client.Dispose();
        }

C# 语言中 File 类和 FileInfo 类都是用来操作文件的，并且作用相似，它们都能完成对文件的创建、更改文件的名称、删除文件、移动文件等操作。
File 类是静态类，其成员也是静态的，通过类名即可访问类的成员；FileInfo 类不是静态成员，其类的成员需要类的实例来访问。
文档操作类，点击查看详细介绍

//
// 摘要:
// Uploads stream into remote file.
//
// 参数:
// input:
// Data input stream.
//
// path:
// Remote file path.
//
// uploadCallback:
// The upload callback.
//
// 异常:
// T:System.ArgumentNullException:
// input is null.
//
// T:System.ArgumentException:
// path is null or contains only whitespace characters.
//
// T:Renci.SshNet.Common.SshConnectionException:
// Client is not connected.
//
// T:Renci.SshNet.Common.SftpPermissionDeniedException:
// Permission to upload the file was denied by the remote host.
// -or-
// A SSH command was denied by the server.
//
// T:Renci.SshNet.Common.SshException:
// A SSH error where System.Exception.Message is the message from the remote host.
//
// T:System.ObjectDisposedException:
// The method was called after the client was disposed.
//
// 言论：
// Method calls made by this method to input, may under certain conditions result
// in exceptions thrown by the stream.