c#.net从ftp下载文件到本地

 string TempFolderPath = System.Configuration.ConfigurationManager.AppSettings["TempFolderPath"].ToString();
 string FtpUserName = System.Configuration.ConfigurationManager.AppSettings["FtpUserName"].ToString();
 string FtpPassWord = System.Configuration.ConfigurationManager.AppSettings["FtpPassWord"].ToString();
 string LocalFileExistsOperation = System.Configuration.ConfigurationManager.AppSettings["LocalFileExistsOperation"].ToString();
 

Uri uri = new Uri(FtpPath);
string FileName = Path.GetFullPath(TempFolderPath) + Path.DirectorySeparatorChar.ToString() +  Path.GetFileName(uri.LocalPath); 

//创建一个文件流
            FileStream fs = null;
            Stream responseStream = null;
            try
            {
                //创建一个与FTP服务器联系的FtpWebRequest对象
                FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uri);
                //设置请求的方法是FTP文件下载
                request.Method = WebRequestMethods.Ftp.DownloadFile;

                //连接登录FTP服务器
                request.Credentials = new NetworkCredential(FtpUserName, FtpPassWord);

                //获取一个请求响应对象
                FtpWebResponse response = (FtpWebResponse)request.GetResponse();
                //获取请求的响应流
                responseStream = response.GetResponseStream();

                //判断本地文件是否存在，如果存在，则打开和重写本地文件

                if (File.Exists(FileName))               

                {
                      if (LocalFileExistsOperation == "write")

                      { 
                              fs = File.Open(FileName, FileMode.Open, FileAccess.ReadWrite);

                      } 
                }

                //判断本地文件是否存在，如果不存在，则创建本地文件
                else             

                {
                        fs = File.Create(FileName);
                }

                if (fs != null)
                {

                    int buffer_count = 65536;
                    byte[] buffer = new byte[buffer_count];
                    int size = 0;
                    while ((size = responseStream.Read(buffer, 0, buffer_count)) > 0)
                    {
                        fs.Write(buffer, 0, size);

                    }
                    fs.Flush();
                    fs.Close();
                    responseStream.Close();
                }
            }
            finally
            {
                if (fs != null)
                    fs.Close();
                if (responseStream != null)
                    responseStream.Close();
            }