Three methods for detecting the existence of remote URLs in asp.net

Copy codeThe Code is as follows:
Private void Page_Load (object sender, System. EventArgs e)
{
String url1 = "http://s.jb51.net /";
String url2 = "http://www.jb51.net/images/logo.gif ";
Response. Write ("<li> Method 1 :");
Response. Write (url1 + ":" + UrlExistsUsingHttpWebRequest (url1). ToString ());
Response. Write ("<li> Method 2 :");
Response. Write (url1 + "exist:" + UrlExistsUsingSockets (url1). ToString ());
Response. Write ("<li> method 3 :");
Response. Write (url1 + "exist:" + UrlExistsUsingXmlHttp (url1). ToString ());
Response. Write ("<li> Method 1 :");
Response. Write (url2 + ":" + UrlExistsUsingHttpWebRequest (url2). ToString ());
Response. Write ("<li> method 3 :");
Response. Write (url2 + "exist:" + UrlExistsUsingXmlHttp (url2). ToString ());
}

Private bool UrlExistsUsingHttpWebRequest (string url ){
Try
{
System. Net. HttpWebRequest myRequest = (System. Net. HttpWebRequest) System. Net. WebRequest. Create (url );
MyRequest. Method = "HEAD ";
MySQL request. Timeout = 100;
System. Net. HttpWebResponse res = (System. Net. HttpWebResponse) myRequest. GetResponse ();
Return (res. StatusCode = System. Net. HttpStatusCode. OK );
}
Catch (System. Net. WebException we)
{
System. Diagnostics. Trace. Write (we. Message );
Return false;
}
}

Private bool UrlExistsUsingXmlHttp (string url)
{
// Note: Msxml2.dll must be referenced in this method.
MSXML2.XMLHTTP _ xmlhttp = new MSXML2.XMLHTTPClass ();
_ Xmlhttp. open ("HEAD", url, false, null, null );
_ Xmlhttp. send ("");
Return (_ xmlhttp. status = 200 );
}
Private bool UrlExistsUsingSockets (string url)
{
If (url. StartsWith ("http: //") url = url. Remove (0, "http: //". Length );
Try
{
System. Net. IPHostEntry ipHost = System. Net. Dns. Resolve (url );
Return true;
}
Catch (System. Net. Sockets. SocketException se)
{
System. Diagnostics. Trace. Write (se. Message );
Return false;
}
}