使用 HtmlAgilityPack 抓取 url 内容会产生错误

Question

我正在使用 HtmlAgilityPack 从 url 中抓取文本，这对大多数网站都运行良好，但对于某些网站，它今天开始出现 return 错误。

错误在行代码 doc = webGet.Load(url); 之后错误信息：The underlying connection was closed: An unexpected error occurred on a send.

不确定为什么我会收到此错误，因为它以前使用此网站 url 示例 url : link

我尝试了 https url，例如 bbc.com，它可以正常工作。如果他们的代码有问题，任何指针

 HtmlDocument doc = new HtmlDocument();
            var url = txtGrabNewsURL.Text.Trim();

        var webGet = new HtmlWeb();
        doc = webGet.Load(url);
        var baseUrl = new Uri(url);
        //  doc.LoadHtml(response);

        String title = (from x in doc.DocumentNode.Descendants()
                        where x.Name.ToLower() == "title"
                        select x.InnerText).FirstOrDefault();

        String desc = (from x in doc.DocumentNode.Descendants()
                       where x.Name.ToLower() == "meta"
                       && x.Attributes["name"] != null
                       && x.Attributes["name"].Value.ToLower() == "description"
                       select x.Attributes["content"].Value).FirstOrDefault();

        String ogImage = (from x in doc.DocumentNode.Descendants()
                          where x.Name.ToLower() == "meta"
                          && x.Attributes["property"] != null
                          && x.Attributes["property"].Value.ToLower() == "og:image"
                          select x.Attributes["content"].Value).FirstOrDefault();


        List<String> imgs = (from x in doc.DocumentNode.Descendants()
                             where x.Name.ToLower() == "img"
                              && x.Attributes["src"] != null
                             select x.Attributes["src"].Value).ToList<String>();

        List<String> imgList = (from x in doc.DocumentNode.Descendants("img")
                                where x.Attributes["src"] != null
                                select x.Attributes["src"].Value.ToLower()).ToList<String>();

完整的错误详细信息

System.Net.WebException was caught
  HResult=-2146233079
  Message=The underlying connection was closed: An unexpected error occurred on a send.
  Source=System
  StackTrace:
       at System.Net.HttpWebRequest.GetResponse()
       at HtmlAgilityPack.HtmlWeb.Get(Uri uri, String method, String path, HtmlDocument doc, IWebProxy proxy, ICredentials creds) in D:\Source\htmlagilitypack.new\Trunk\HtmlAgilityPack\HtmlWeb.cs:line 1355
       at HtmlAgilityPack.HtmlWeb.LoadUrl(Uri uri, String method, WebProxy proxy, NetworkCredential creds) in D:\Source\htmlagilitypack.new\Trunk\HtmlAgilityPack\HtmlWeb.cs:line 1479
       at HtmlAgilityPack.HtmlWeb.Load(String url, String method) in D:\Source\htmlagilitypack.new\Trunk\HtmlAgilityPack\HtmlWeb.cs:line 1106
       at HtmlAgilityPack.HtmlWeb.Load(String url) in D:\Source\htmlagilitypack.new\Trunk\HtmlAgilityPack\HtmlWeb.cs:line 1061
       at _admin_News.btnGrabNews_Click(Object sender, EventArgs e) in c:\path\News.aspx.cs:line 361
  InnerException: System.IO.IOException
       HResult=-2146232800
       Message=Authentication failed because the remote party has closed the transport stream.
       Source=System
       StackTrace:
            at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
            at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
            at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
            at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
            at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
            at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
            at System.Net.TlsStream.CallProcessAuthentication(Object state)
            at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
            at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
            at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
            at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result)
            at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size)
            at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size)
            at System.Net.ConnectStream.WriteHeaders(Boolean async)
       InnerException:

Answer 1

我是运行我本地机器上的代码它工作正常并且得到了没有任何错误的输出。我还以为那个时候网站打不开了，是连接问题。

   HtmlDocument doc = new HtmlDocument();
        var url = "https://m.gulfnews.com/business/sectors/banking/rebuilding-lives-10-years-after-lehman-s-fall-1.2277318"

    var webGet = new HtmlWeb();
    doc = webGet.Load(url);

    String title = (from x in doc.DocumentNode.Descendants()
                    where x.Name.ToLower() == "title"
                    select x.InnerText).FirstOrDefault();

输出：重建生活，10。 . . . .等等

Answer 2

如果它只发生在 HTTPS 资源上，您的目标是 .Net 4，那么它可能与默认的 SSL/TLS 支持有关。请尝试以下操作：

using System.Net;

static void Main()
{
    //place this anywhere in your code prior to invoking the Web request
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12 |  SecurityProtocolType.Ssl3; 
}

使用 HtmlAgilityPack 抓取 url 内容会产生错误

Grabing url contents using HtmlAgilityPack generates error

c#

asp.net

webforms

html-agility-pack