[英]C# System.InvalidCastException
Why I'm getting this error? 为什么我会收到此错误?
System.InvalidCastException was unhandled by user code
Message=Specified cast is not valid.
Source=System.Windows.Forms
StackTrace:
at System.Windows.Forms.UnsafeNativeMethods.IHTMLDocument2.GetLocation()
at System.Windows.Forms.WebBrowser.get_Document()
at System.Windows.Forms.WebBrowser.get_DocumentStream()
at System.Windows.Forms.WebBrowser.get_DocumentText()
at SiteBot.MainWindow.backgroundWorker1_DoWork(Object sender, DoWorkEventArgs e) in D:\Documents\Visual Studio 2010\Projects\SiteBot\MainWindow.cs:line 35
at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)
InnerException:
The following solves your cross thread issue. 以下内容解决了您的跨线程问题。
public delegate string GetStringHandler();
public string GetDocumentText()
{
if (InvokeRequired)
return Invoke(new GetStringHandler(GetDocumentText)) as string;
else
return webBrowser.DocumentText;
}
if (regAddId.IsMatch(GetDocumentText()))
{
}
I get a threading exception with this test: 我在此测试中遇到线程异常:
public class Test
{
private readonly WebBrowser wb;
public Test()
{
wb = new WebBrowser();
var bw = new BackgroundWorker();
bw.DoWork += DoWork;
bw.RunWorkerAsync();
while (bw.IsBusy)
{
Thread.Sleep(10);
Application.DoEvents();
}
}
private void DoWork(object sender, DoWorkEventArgs e)
{
wb.Navigate(@"www.clix-cents.com/pages/clickads");
Thread.Sleep(1000);
var regex = new Regex("onclick=\\'openad\\(\"([\\d\\w]+\"\\);");
regex.IsMatch(wb.DocumentText);
}
}
public class Program
{
[STAThread]
public static void Main(string[] args)
{
new Test();
}
}
The exception looks like this: 异常如下所示:
Since WebBrowser is really just a wrapper around IE's ActiveX control, you'll need to be careful about threading issues. 由于WebBrowser实际上只是IE的ActiveX控件的包装,因此您需要注意线程问题。 I think what you really want to use here is a WebClient and not a WebBrowser, but I'm just guessing about your application.
我认为您真正想在这里使用的是WebClient,而不是WebBrowser,但我只是在猜测您的应用程序。
[EDIT] [编辑]
Like @Fun states you can just Invoke over to the GUI thread (assuming thats where the control was created. I'd still recommend using a WebClient. 像@Fun状态一样,您可以调用GUI线程(假设多数民众赞成在创建控件的位置。我仍然建议使用WebClient。
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