http - 如何使用asp.net获取网页的标题

Question

我正在尝试获取网页的标题。下面的代码块完成了这项工作。
但是，当页面被 401 拒绝时，我根本无法获得任何标题。有办法吗？

谢谢

public Int32 CheckURLStatus(string uri, out HttpWebResponse _response)
    {
        //Get response header
        _response = null;
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
        HttpWebRequest _request = (HttpWebRequest)WebRequest.Create(uri);
        _request.Method = "GET";
        _request.AllowAutoRedirect = true;
        _request.Accept = "*/*";
        _request.MaximumAutomaticRedirections = 4;
        _request.UseDefaultCredentials = true;
        _request.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;
        Int32 statusCode = 404;
        try
        {
            _response = (HttpWebResponse)_request.GetResponse();
            statusCode = Convert.ToInt32(_response.StatusCode);
        }
        catch (Exception ex)
        {
            _response = null;
        }
        return statusCode;
    }

Answer 1

如果任何 StatusCode 不是 200，GetResponse() 方法将引发 WebException。要获取状态代码，您必须处理此异常并从异常中的响应中获取状态代码。

即使在 WebException 的情况下，我也更改了您的代码以获取响应代码：

public Int32 CheckURLStatus(string uri, out HttpWebResponse _response)
    {
        //Get response header
        _response = null;
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
        HttpWebRequest _request = (HttpWebRequest)WebRequest.Create(uri);
        _request.Method = "GET";
        _request.AllowAutoRedirect = true;
        _request.Accept = "*/*";
        _request.MaximumAutomaticRedirections = 4;
        _request.UseDefaultCredentials = true;
        _request.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;
        Int32 statusCode = 404;
        try
        {
            _response = (HttpWebResponse)_request.GetResponse();
            statusCode = Convert.ToInt32(_response.StatusCode);
        }
        catch (WebException ex)
        {
            statusCode = Convert.ToInt32(((HttpWebResponse)ex.Response).StatusCode);
            _response = null;
        }
        return statusCode;
    }

您还可以检查 ex.Response.Headers 并且您将获得响应的 HTTP 标头。