WebException：远程服务器返回错误：NotFound Windows Phone Youtube Html

Question

我想用windows phone应用程序的以下代码获取YouTube内搜索结果中的元素和标签。下面

public partial class Page1 : PhoneApplicationPage 
{ 
    string keyword; 
    public Page1() 
    { 
     InitializeComponent(); 

    } 

    protected override void OnNavigatedTo(NavigationEventArgs e) 
    { 
     NavigationContext.QueryString.TryGetValue("parameter", out keyword); 
     LoadResults(); 
    } 

    public void LoadResults() 
    {   
     WebClient codeSampleReq = new WebClient(); 
     codeSampleReq.DownloadStringCompleted += codeSampleReq_DownloadStringCompleted; 
     codeSampleReq.DownloadStringAsync(new Uri("https://www.youtube.com/results?search_query=" + keyword)); 
    } 



    void codeSampleReq_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e) 
    { 
     try 
     { 
      HtmlDocument htmlDoc = new HtmlAgilityPack.HtmlDocument(); 
      htmlDoc.OptionFixNestedTags = true; 
      htmlDoc.LoadHtml(e.Result); 
      HtmlNode divContainer = htmlDoc.GetElementbyId("a"); 
      if (divContainer != null) 
      { 
       HtmlNodeCollection nodes = divContainer.SelectNodes("a"); 
       foreach (HtmlNode trNode in nodes) 
       { 

       } 
      } 
     } 
     catch (Exception ex) 
     { 
      MessageBox.Show("Unable to download" + ex.Message); 
     } 
    } 
} 

，并得到例外：

{System.Net.WebException: The remote server returned an error: NotFound. ---> System.Net.WebException: The remote server returned an error: NotFound. at System.Net.Browser.ClientHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult) at System.Net.Browser.ClientHttpWebRequest.<>c__DisplayClasse.b__d(Object sendState) at System.Net.Browser.AsyncHelper.<>c__DisplayClass1.b__0(Object sendState) --- End of inner exception stack trace --- at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state) at System.Net.Browser.ClientHttpWebRequest.EndGetResponse(IAsyncResult asyncResult) at System.Net.WebClient.GetWebResponse(WebRequest request, IAsyncResult result) at System.Net.WebClient.DownloadBitsResponseCallback(IAsyncResult result)}

有谁知道为什么服务器返回404没有发现？
注意：关键字只能是“ali，veli，kadir”或其他字符串。

Answer 1

NotFound是WebClient的响应多种错误。两种最常见的情况是

• 坏的服务器证书（不应该是你的情况下，YouTube已经有效证书）
• 在模拟器或设备没有互联网连接。

我几乎可以肯定你的情况是第二个，检查你的互联网连接。