ASP.NET实例：检测远程URL是否存在的三种方法

本文用3种方法检测远程URL是否存在。 it55.com

private void Page_Load(object sender, System.EventArgs e)
{ vd;k;l www.it55.com rdfg

string url1 = "http://www.dwww.cn/";
string url2 = "http://www.dwww.cn/Images/logo1.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()); www.it55.com

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 ); IT资讯之家 www.it55.com
} vd;k;l www.it55.com rdfg

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;
}
}

（编辑：IT资讯之家 www.it55.com）