检测远程URL是否存在的三种方法
检测远程URL是否存在的三种方法
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。
private void Page_Load(object sender, System.EventArgs e)
{
string url1 = 'http://dotnet.aspx.cc/';
string url2 = '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;
}
}