前些时日，项目中用到了一些FTP操作。近日一朋友又问我如何获取FTP目录的最后修改日期，所以就总结一下。

获取FTP文件的最后修改日期，可用GetDateTimestamp方法，代码如下：

FtpWebRequest req = (FtpWebRequest)FtpWebRequest.Create("ftp://ftp.free1.dns4u.cn/web/test.txt");
            req.Method = WebRequestMethods.Ftp.GetDateTimestamp;

            req.Credentials = new NetworkCredential("abc110", "123456");

            FtpWebResponse response = (FtpWebResponse)req.GetResponse();
            label1.Text = response.LastModified.ToString();
            response.Close();
            response = null;
            req = null;

但是这种方法，只能够获取文件的最后修改日期，如果是目，就会报错。

要得到文侠的最后修改日期，只能用ListDirectoryDetails方法，下代码是获取cert目录修改日期的

 FtpWebRequest req = (FtpWebRequest)FtpWebRequest.Create("ftp://ftp.free1.dns4u.cn/web/");
            req.Method = WebRequestMethods.Ftp.ListDirectoryDetails;

            req.Credentials = new NetworkCredential("abc110", "123456");

            FtpWebResponse response = (FtpWebResponse)req.GetResponse();
            StreamReader reader = new StreamReader(response.GetResponseStream());
            string str = "";
            do
            {
                str = reader.ReadLine();
                if (string.IsNullOrEmpty(str))
                    break;
                if(str.Substring(str.LastIndexOf(" ")).ToLower().Trim()=="cert")
                label1.Text += str + "\r\n";
            }
            while (!string.IsNullOrEmpty(str));
            reader.Close();
            response.Close();
            response = null;
            req = null;