健壮的函数验证

public ValidateResult Validate(

      bool useHeadMethod = true,

      bool enableKeepAlive = false,

      int timeoutSeconds = 30 )

{

    ValidateResult result = new ValidateResult();

 

    HttpWebRequest request = WebRequest.Create(Uri)

                                  as HttpWebRequest;

    if (useHeadMethod)

    {

        request.Method = "HEAD";

    }

    else

    {

        request.Method = "GET";

    }

 

    // always compress, if you get back a 404 from a HEAD

    //     it can be quite big.

    request.AutomaticDecompression = DecompressionMethods.GZip;

    request.AllowAutoRedirect = false;

    request.UserAgent = UserAgentString;

    request.Timeout = timeoutSeconds * 1000;

    request.KeepAlive = enableKeepAlive;

 

    HttpWebResponse response = null;

    try

    {

        response = request.GetResponse() as HttpWebResponse;

 

        result.StatusCode = response.StatusCode;

        if (response.StatusCode ==

                   HttpStatusCode.Redirect ||

            response.StatusCode ==

                   HttpStatusCode.MovedPermanently ||

            response.StatusCode ==

                   HttpStatusCode.SeeOther ||

            response.StatusCode ==

                   HttpStatusCode.TemporaryRedirect)

        {

            try

            {

                Uri targetUri =

                  new Uri(Uri, response.Headers["Location"]);

                var scheme = targetUri.Scheme.ToLower();

                if (scheme == "http" || scheme == "https")

                {

                    result.RedirectResult =

                        new ExternalUrl(targetUri);

                }

                else

                {

                    // this little gem was born out of

                    //   http://tinyurl.com/18r

                    //   redirecting to about:blank

                    result.StatusCode =

                           HttpStatusCode.SwitchingProtocols;

                    result.WebExceptionStatus = null;

                }

            }

            catch (UriFormatException)

            {

                // another gem ... people sometimes redirect to

                //    http://nonsense:port/yay

                result.StatusCode =

                    HttpStatusCode.SwitchingProtocols;

                result.WebExceptionStatus =

                    WebExceptionStatus.NameResolutionFailure;

            }

 

        }

 

 

参考文章：  

http://blog.jobbole.com/22288/