我正在尝试开发一个Windows手机应用程序,它将HTML页面(通过Web检索)解析为HTMLDocument变量,并使用它来检查页面,检索值等等。即使在尝试连接到像BBC新闻主页这样的页面时也是如此我收到了一个错误。
System.TypeAccessException: Attempt by security transparent method 'HtmlAgilityPack.HtmlWeb.LoadFromWebAsync(System.Uri, System.Text.Encoding, System.Net.NetworkCredential)' to access security critical type 'System.Net.NetworkCredential' failed.
at HtmlAgilityPack.HtmlWeb.LoadFromWebAsync(Uri uri, Encoding encoding, NetworkCredential credentials)
at HtmlAgilityPack.HtmlWeb.<LoadFromWebAsync>d__0.MoveNext()
这个页面不应该需要凭据,所以我很困惑为什么我遇到这个错误。这是代码。
private async Task GetHtmlDocument(string url)
{
Debug.WriteLine("This is a line");
try
{
HtmlWeb web = new HtmlWeb();
HtmlDocument rootDocument = await web.LoadFromWebAsync(url);
}
catch (Exception e)
{
Debug.WriteLine("Exception: " + e);
}
}
我正在使用Windows Phone 8.1,我可能需要在问题中提及。以下是有效的。
private async Task GetHtmlDocument(string url)
{
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
request.Credentials = new LoginCredentials().Credentials;
try
{
WebResponse myResponse = await request.GetResponseAsync();
HtmlAgilityPack.HtmlDocument htmlDoc = new HtmlAgilityPack.HtmlDocument();
htmlDoc.OptionFixNestedTags = true;
htmlDoc.Load(myResponse.GetResponseStream());
} catch (...) { ... }
}
我通过html-agility-pack
解析Html
,如下所示:
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
//cookie if you need
request.CookieContainer = cookie;
//WebRequestMethods.Http.Get
//or WebRequestMethods.Http.Post
request.Method = method;
request.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36";
request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
request.Headers.Add("Accept-Language", "ru-RU,ru;q=0.8,en-US;q=0.6,en;q=0.4");
request.ServicePoint.Expect100Continue = false;
request.Timeout = 100000;
request.ContentType = "application/x-www-form-urlencoded";
using (WebResponse myResponse = request.GetResponse())
{
HtmlAgilityPack.HtmlDocument htmlDoc = new HtmlAgilityPack.HtmlDocument();
htmlDoc.OptionFixNestedTags = true;
htmlDoc.Load(myResponse.GetResponseStream(), Encoding.GetEncoding(1251));
}
接着
string text;
HtmlAgilityPack.HtmlNode node = _doc.DocumentNode.SelectSingleNode(Xpath);
if (node != null) text = node.InnerText;