[FTP]測試FTP連線狀態

2014-10-28

摘要:[FTP]測試FTP連線狀態

因為工作需要要測試FTP連線狀態


        /// 
        /// 測試連接狀態
        /// 
        ///
        ///
        ///
        /// 
        private bool isValidConnection(string url, string user, string password)
        {
            FtpWebRequest request;
            try
            {
                request = (FtpWebRequest)FtpWebRequest.Create(@"ftp://" + url);
                request.Method = WebRequestMethods.Ftp.ListDirectory;
                request.KeepAlive = true;
                request.Credentials = new NetworkCredential(user, password);
                request.GetResponse();
            }
            catch (WebException ex)
            {
                return false;
            }
            finally
            {
                request = null;
            }

            return true;
        }

但是如果這樣連續測試2次會發現第3次會逾時

後來搜了很久　雖然是同問題看到以下這篇感覺不清不楚

http://epaper.blueshop.com.tw/board/show.asp?subcde=BRD20130607204525V2R&fumcde=FUM20050124192253INM

.NET 預設對同個ServicePoint可以有兩個連線
要增加可以寫


1	//設定單個ServicePoint的最大連線數
2	ServicePointManager.DefaultConnectionLimit = 4;
	開新視窗(view plain) \| 列印(print) \| ?

但是這樣還是會爆
因為連線連了並不會釋放
所以


1	//連線前設定如果斷線了會釋放連線數
2	request.KeepAlive = false;
3	//連線完設定回來
4	request.KeepAlive = true;
	開新視窗(view plain) \| 列印(print) \| ?

你可在程式debug中watch ServicePointManager 或是 request內有關connection的值

後來再去搜發現

http://blog.xuite.net/tolarku/blog/32757529-VB.NET+concurrent+connect+%E9%99%90%E5%88%B6+2%E7%AD%86+-+webrequest

裡面的這一段

Dim iresponse As HttpWebResponse = irequest.GetResponse

MessageBox.Show(capture_url & "\n URL Exists.")

iresponse.close() '釋放已用完的 webresponse

後來想了一下　改入下面那2行


var response = request.GetResponse();
                response.Close();

就解決了


        /// 
        /// 測試連接狀態
        /// 
        ///
        ///
        ///
        /// 
        private bool isValidConnection(string url, string user, string password)
        {
            FtpWebRequest request;
            try
            {
                request = (FtpWebRequest)FtpWebRequest.Create(@"ftp://" + url);
                request.Method = WebRequestMethods.Ftp.ListDirectory;
                request.KeepAlive = true;
                request.Credentials = new NetworkCredential(user, password);
                var response = request.GetResponse();
                response.Close();
            }
            catch (WebException ex)
            {
                return false;
            }
            finally
            {
                request = null;
            }

            return true;
        }

結論:恩多學一個是一個

尾語:聽說正在做不符道德的事，多做好事可以心安！

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