检测远程URL是否存在的三种方法

王朝other·作者佚名  2006-05-27
宽屏版  字体: |||超大  

本文用3种方法检测远程URL是否存在。

private void Page_Load(object sender, System.EventArgs e)

{

string url1 = "http://dotnet.aspx.cc/[/url]";

string url2 = "[url=http://dotnet.aspx.cc/Images/logo.gif]http://dotnet.aspx.cc/Images/logo.gif";

Response.Write("<li>方法1:");

Response.Write(url1 + " 存在:" + UrlExistsUsingHttpWebRequest(url1).ToString());

Response.Write("<li>方法2:");

Response.Write(url1 + " 存在:" + UrlExistsUsingSockets(url1).ToString());

Response.Write("<li>方法3:");

Response.Write(url1 + " 存在:" + UrlExistsUsingXmlHttp(url1).ToString());

Response.Write("<li>方法1:");

Response.Write(url2 + " 存在:" + UrlExistsUsingHttpWebRequest(url2).ToString());

Response.Write("<li>方法3:");

Response.Write(url2 + " 存在:" + UrlExistsUsingXmlHttp(url2).ToString());

}

private bool UrlExistsUsingHttpWebRequest(string url)

{

try

{

System.Net.HttpWebRequest myRequest =(System.Net.HttpWebRequest)System.Net.WebRequest.Create(url);

myRequest.Method = "HEAD";

myRequest.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)

{

//注意:此方法需要引用Msxml2.dll

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;

}

}

 
 
 
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