Thousands of companies worldwide rely on edtFTPnet/Free to add FTP to their .NET applications. It is a mature, optimized library that has been proven over many years of use.

• Robust and proven FTP library
• Supports resuming of transfers, active and passive mode, binary and ASCII.
• Open source so source code is included
• Free for commercial use (under the LGPL license)
• Option of purchasing a non-GPL license and support is always available

edtFTPnet官方网站：
http://www.enterprisedt.com/products/edtftpnet/

下载后在bin目录中找到edtFTPnet.dll，在项目中添加引用。
下面为一些用法：

1、FTP服务器根目录为web，在它下面创建如下图示的目录和上传文件

FTPConnection.CommandEncoding = Encoding.GetEncoding("GBK") 指定GBK编码以支持中文文件名
FTPConnection.CreateDirectory() 创建指定目录
FTPConnection.ChangeWorkingDirectory() 切换到指定目录
FTPConnection.UploadFile() 上传文件

web
|-----L11
       |-----L21            
              |-----L31
                      |-----31.htm
              |-----21.htm
       |-----L22
       |-----11.htm
       |-----目录.txt

private const string ftpServerIP = "xx.xx.xx.xx";  private const string ftpRemotePath = "web";  private const string ftpUserID = "user";  private const string ftpPassword = "123";    private void btnCreateAndUpload_Click(object sender, EventArgs e)  {                using (var conn = new FTPConnection      {          ServerAddress = ftpServerIP,          ServerDirectory = ftpRemotePath,          UserName = ftpUserID,          Password = ftpPassword,          CommandEncoding = Encoding.GetEncoding("GBK")      })      {          conn.Connect();                            //创建目录L11          conn.CreateDirectory("L11");            //============切换当前工作目录到L11============          conn.ChangeWorkingDirectory("L11");          //上行代码也可以用conn.ServerDirectory = "L11";            //上传"文档.txt"          conn.UploadFile("文档.txt", "文档.txt");            //创建子目录L21,L22          conn.CreateDirectory("L21");          conn.CreateDirectory("L22");            //在当前工作目录L11上传文件"L11.htm"          conn.UploadFile("11.htm", "11.htm");            //============切换当前工作目录到L21============          conn.ChangeWorkingDirectory("L21");            //上传文件21.htm          conn.UploadFile("21.htm", "21.htm");          //创建目录L31          conn.CreateDirectory("L31");            //============切换当前工作目录到L31============          conn.ChangeWorkingDirectory("L31");            //上传文件31.htm          conn.UploadFile("31.htm", "31.htm");      }  }

2、获取文件信息

FTPConnection.GetFileInfos() 获取文件和目录详细信息，结果的一个属性Dir为true表示为目录，否则为文件

private void btnList_Click(object sender, EventArgs e)  {      using (var conn = new FTPConnection      {          ServerAddress = ftpServerIP,          ServerDirectory = ftpRemotePath,          UserName = ftpUserID,          Password = ftpPassword,          CommandEncoding = Encoding.GetEncoding("GBK")      })      {          conn.Connect();          //获取指定目录的所有子目录和文件信息          conn.ChangeWorkingDirectory("L11/L21");                         var files1 = conn.GetFileInfos();          ShowFileInfos(files1);          /*结果如下：           File, /web/L11/L21/21.htm, 21.htm, 11.2KB, 2013-9-26 14:51:00           Dir, /web/L11/L21/L31, L31, 0KB, 2013-9-26 14:51:00           */            ////返回上级目录，例子中为web/L11          conn.ChangeWorkingDirectoryUp();          var files2 = conn.GetFileInfosRecursive();          ShowFileInfos(files2);          /*结果如下：          File, /web/L11/11.htm, 11.htm, 59.4KB, 2013-9-26 14:51:00          Dir, /web/L11/L21, L21, 0KB, 2013-9-26 14:51:00          Dir, /web/L11/L22, L22, 0KB, 2013-9-26 14:51:00          File, /web/L11/文档.txt, 文档.txt, 40.8KB, 2013-9-26 14:51:00          File, /web/L11/L21/21.htm, 21.htm, 11.2KB, 2013-9-26 14:51:00          Dir, /web/L11/L21/L31, L31, 0KB, 2013-9-26 14:51:00          File, /web/L11/L21/L31/31.htm, 31.htm, 5.6KB, 2013-9-26 14:51:00           */      }  }        void ShowFileInfos(FTPFile[] files)  {      foreach (var file in files)      {          string info = string.Format("{0}, {1}, {2}, {3}KB, {4}",              file.Dir ? "Dir" : "File", file.Path, file.Name, Math.Round(file.Size / 1024.0, 1), file.LastModified);          richTextBox1.AppendText(info + "\r\n");      }      richTextBox1.AppendText("\r\n");  }

其中递归获取指定目录的所有子目录和文件信息的扩展方法GetFileInfosRecursive如下：

public static class FtpClientExtensions  {      /// <summary>      /// 递归获取目录的所有子目录和文件信息      /// </summary>      public static FTPFile[] GetFileInfosRecursive(this FTPConnection conn)      {          var resultList = new List<FTPFile>();          var fileInfos = conn.GetFileInfos();          resultList.AddRange(fileInfos);          foreach (var fileInfo in fileInfos)          {              if (fileInfo.Dir)              {                  conn.ServerDirectory = fileInfo.Path;                  resultList.AddRange(conn.GetFileInfosRecursive());              }          }          return resultList.ToArray();      }      /// <summary>      /// 递归删除目录(包括所有子目录和文件信息)      /// </summary>      public static void DeleteDirectoryRecursive(this FTPConnection conn, string directoryName)      {          conn.ChangeWorkingDirectory(directoryName);          var fileInfos = conn.GetFileInfos();          foreach (var fileInfo in fileInfos)          {              if (fileInfo.Dir)                  conn.DeleteDirectoryRecursive(fileInfo.Name);              else                  conn.DeleteFile(fileInfo.Name);          }          conn.ChangeWorkingDirectoryUp();          conn.DeleteDirectory(directoryName);      }  }

3、删除目录及所有子目录和文件

FTPConnection.DeleteDirectory()当删除的目录不为空时，会出错，需递归删除，
递归删除目录扩展方法DeleteDirectoryRecursive见上面类FtpClientExtensions

private void btnDelete_Click(object sender, EventArgs e)  {      using (var conn = new FTPConnection      {          ServerAddress = ftpServerIP,          ServerDirectory = ftpRemotePath,          UserName = ftpUserID,          Password = ftpPassword,          CommandEncoding = Encoding.GetEncoding("GBK")      })      {          conn.Connect();                        //递归删除目录及所有子目录和文件          conn.DeleteDirectoryRecursive("L11");          //如果删除单个文件，路径为当前目录的相对路径          //conn.DeleteFile("L11/11.htm");      }  }