参考网站:http://www.cnblogs.com/junny/archive/2012/10/30/2745978.html
public bool CheckUrlVisit(string url) { try { HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url); HttpWebResponse resp = (HttpWebResponse)req.GetResponse(); if (resp.StatusCode == HttpStatusCode.OK) {
resp.Close(); return true; } } catch (WebException webex) { return false; } return false; }