C#获取ftp文件最后修改时间

public static DateTime GetFileModifyDateTime(string ftpServerIP,string ftpFolder,string ftpUserID,string ftpPwd, string fileName)

{
  FtpWebRequest reqFTP=null;
  try
  {
  if (ftpFolder != "")
  {
  ftpFolder = ftpFolder.Replace("/", "").Replace("\\", "");
  ftpFolder = "/" + ftpFolder;
  }
  string ftpPath = "ftp://" + ftpServerIP + ftpFolder + "/" + fileName;

reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpPath));
    
  reqFTP.UseBinary = true;
  //reqFTP.UsePassive = false;
  reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPwd);

reqFTP.Method = WebRequestMethods.Ftp.GetDateTimestamp;

FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();

DateTime dt = response.LastModified;
    
  response.Close();
  response = null;
  reqFTP = null;
  return dt;
  }
  catch (Exception ex)
  {
  throw ex;
  }  
  }