Question

我有一个名为submit_Button的按钮，在 OnClicked 事件中包含以下代码：

    Thread thread = new Thread(new ThreadStart(heavyWork));
    thread.Start();

heavyWork 功能代码：

private void heavyWork()
{
    DisableUI();

    string Name = Name_textBox.Text;
    celebrityName = Name.Replace(" ", "+");
    string queryURL = "http://stackoverflow.com";

    HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(queryURL);
    request.Method = "GET";
    // make request for web page
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    StreamReader htmlSource = new StreamReader(response.GetResponseStream());

    string htmlStringSource = string.Empty;
    htmlStringSource = htmlSource.ReadToEnd();
    response.Close();

    //var regex = new Regex(@"<FONT class=""result"">(.*?)</FONT>");
    var regex = new Regex(@"<span class=""kno-a-v"">(.*?)</span>");
    var match = regex.Match(htmlStringSource);
    var result = match.Groups[1].Value;

    result = HttpUtility.HtmlDecode(result);
    MessageBox.Show(result);

    EnableUI();
}

// Functions
private void DisableUI()
{
    celebrityName_textBox.IsEnabled = false;
    submit_Button.IsEnabled = false;
    infoType_listBox.IsEnabled = false;
    preloader_Image.Visibility = Visibility.Visible;
}

private void EnableUI()
{
    celebrityName_textBox.IsEnabled = true;
    submit_Button.IsEnabled = true;
    infoType_listBox.IsEnabled = true;
    preloader_Image.Visibility = Visibility.Hidden;
}

当我运行应用程序，然后按下按钮时，应用程序立即崩溃！

发生了什么事？我尝试使用 BackgroundWorker ，但是当我worker.RunWorkerAsync()没有任何反应时（工作人员无法启动）。

Answer 1

DisableUI（）正在更改不是UI线程的线程上的UI控件的状态。这在WPF中是不允许的，因为它是single threaded UI framework，并且只允许您更改对UI线程的控件。 Dispatcher.Invoke（）/ BeginInvoke（）是你的朋友。

Good MSDN article on using the Dispatcher

Answer 2

您将要在UI线程上执行任何与UI相关的操作，您可以使用调度程序执行此操作，如下所示：

private void heavyWork()
{
    Application.Current.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(DisableUI));
    //rest of method
    Application.Current.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(EnableUI));
}

Answer 3

使用Background Worker时，您的代码应如下所示：请注意，当您启动 worker.RunWorkerAsync（）方法时，会调用BackgroundWorker Do Work

BackgroundWorker _backgroundWorker = new BackgroundWorker
{
   WorkerReportsProgress = true,
   WorkerSupportsCancellation = true
};
_backgroundWorker.DoWork += BackgroundWorkerDoWork;
_backgroundWorker.RunWorkerCompleted += BackgroundWorkerRunWorkerCompleted;

 void BackgroundWorkerDoWork(object sender, DoWorkEventArgs e)
 {
     //DU STUFF HERE
 }

void BackgroundWorkerRunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    /DO STUFF HERE LIKE HIDE / SHOW / ENABLE/ DISABLE buttons
}

使用System.Threading.Thread时WPF应用程序崩溃

3 个答案: