HtmlAgilityPack WebGet.Load給出錯誤「對象引用未設置爲對象的實例」

我在關於從經銷商網站獲取新車價格的項目。我可以獲取大多數網站的HTML。但是，當我嘗試加載其中一個WebGet.Load（url）方法給出Object reference not set to an instance of an object.錯誤。我找不到這些網站之間的任何區別。HtmlAgilityPack WebGet.Load給出錯誤「對象引用未設置爲對象的實例」

正常工作URL的例子：

http://www.renault.com.tr/page.aspx?id=1715

http://www.hyundai.com.tr/tr/Content.aspx?id=fiyatlistesi

網站問題：

http://www.fiat.com.tr/Pages/tr/otomobiller/grandepunto_fiyat.aspx

謝謝您的幫助。

var webGet = new HtmlWeb(); 
var document = webGet.Load("http://www.fiat.com.tr/Pages/tr/otomobiller/grandepunto_fiyat.aspx");

當我使用此url文件未加載。

來源

2011-01-22 Barış

您可以發佈您的代碼？ – 2011-01-22 11:42:54

你可以發佈完整的堆棧框架嗎？ – 2011-01-22 16:53:27

實際的問題是在HtmlAgilityPack內部。該網頁無法正常工作，此元內容類型爲：<META http-equiv="Content-Type" content="text/html; charset=8859-9">，其中charset=8859-9似乎是不合法的。 HAL內部試圖通過使用類似於Encoding.GetEncoding("8859-9")的東西來獲得適當的編碼，這會引發錯誤（我認爲實際編碼應該是iso-8859-9）。

其實你需要的是告訴HAL不讀的HtmlDocument（只是HtmlDocument.OptionReadEncoding = true）編碼，但這似乎是不可能的HtmlWeb.Load（設置HtmlWeb.AutoDetectEncoding不在這裏工作）。所以，解決方法可能是手動讀取url（最簡單的方法）：

var document = new HtmlDocument(); 
document.OptionReadEncoding = false; 

var url = 
    new Uri("http://www.fiat.com.tr/Pages/tr/otomobiller/grandepunto_fiyat.aspx"); 
var request = (HttpWebRequest)WebRequest.Create(url); 
request.Method = "GET"; 
using (var response = (HttpWebResponse)request.GetResponse()) 
{ 
    using (var stream = response.GetResponseStream()) 
    { 
     document.Load(stream, Encoding.GetEncoding("iso-8859-9")); 
    } 
}

這個工作，併成功解析頁面。

編輯： @：西蒙Mourier：是的，它提出了NullReferenceException因爲它抓住ArgumentException並設置_declaredencoding = null那裏。然後_declaredencoding.WindowsCodePage行將引發空引用。

這裏距離HtmlDocument.cs一個代碼塊，ReadDocumentEncoding方法：

try 
{ 
    _declaredencoding = Encoding.GetEncoding(charset); 
} 
catch (ArgumentException) 
{ 
    _declaredencoding = null; 
} 
if (_onlyDetectEncoding) 
{ 
    throw new EncodingFoundException(_declaredencoding); 
} 

if (_streamencoding != null) 
{ 
    if (_declaredencoding.WindowsCodePage != _streamencoding.WindowsCodePage) 
    { 
     AddError(
      HtmlParseErrorCode.CharsetMismatch, 
      _line, _lineposition, 
      _index, node.OuterHtml, 
      "Encoding mismatch between StreamEncoding: " + 
      _streamencoding.WebName + " and DeclaredEncoding: " + 
      _declaredencoding.WebName); 
    } 
}

這裏是我的堆棧跟蹤：

System.NullReferenceException was unhandled 
    Message=Object reference not set to an instance of an object. 
    Source=HtmlAgilityPack 
    StackTrace: 
     at HtmlAgilityPack.HtmlDocument.ReadDocumentEncoding(HtmlNode node) in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlDocument.cs:line 1916 
     at HtmlAgilityPack.HtmlDocument.PushNodeEnd(Int32 index, Boolean close) in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlDocument.cs:line 1805 
     at HtmlAgilityPack.HtmlDocument.Parse() in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlDocument.cs:line 1468 
     at HtmlAgilityPack.HtmlDocument.Load(TextReader reader) in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlDocument.cs:line 769 
     at HtmlAgilityPack.HtmlDocument.Load(Stream stream, Boolean detectEncodingFromByteOrderMarks) in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlDocument.cs:line 597 
     at HtmlAgilityPack.HtmlWeb.Get(Uri uri, String method, String path, HtmlDocument doc, IWebProxy proxy, ICredentials creds) in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlWeb.cs:line 1515 
     at HtmlAgilityPack.HtmlWeb.LoadUrl(Uri uri, String method, WebProxy proxy, NetworkCredential creds) in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlWeb.cs:line 1563 
     at HtmlAgilityPack.HtmlWeb.Load(String url, String method) in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlWeb.cs:line 1152 
     at HtmlAgilityPack.HtmlWeb.Load(String url) in C:\Source\htmlagilitypack\Trunk\HtmlAgilityPack\HtmlWeb.cs:line 1107 
     at test.console.Program.Main(String[] args) in W:\Projects\Me\test.console\test.console\Program.cs:line 54 
     at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) 
     at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) 
     at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() 
     at System.Threading.ThreadHelper.ThreadStart_Context(Object state) 
     at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) 
     at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) 
     at System.Threading.ThreadHelper.ThreadStart() 
    InnerException:

來源

2011-05-10 16:34:38 Alex

HtmlAgilityPack WebGet.Load給出錯誤「對象引用未設置爲對象的實例」

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