Question

我正在努力应对WP7中的跨线程操作。元素已成功添加到ObservableCollection但不显示任何内容。数据绑定ListBox（lBox）给出：

无效的跨线程访问。

这就是我所拥有的：

public partial class MainPage : PhoneApplicationPage
{
    private ObservableCollection<string> obrazkiFinal = new ObservableCollection<string>();

    public ObservableCollection<string> ObrazkiFinal
    {
        get { return obrazkiFinal; }
        set { obrazkiFinal = value; }
    }

    // Constructor
    public MainPage()
    {
        InitializeComponent();
    }

    private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
    {
        lBox.ItemsSource = ObrazkiFinal;

        HttpWebRequest httpRequest = WebRequest.CreateHttp(@"http://website");
        IAsyncResult res = httpRequest.BeginGetResponse(new AsyncCallback(RespResult),httpRequest);
    }

    private void RespResult(IAsyncResult respResylt)
    {
        var res = (HttpWebRequest)respResylt.AsyncState;
        var resp = res.EndGetResponse(respResylt);

        /* some parsing code */
         foreach (/* found pic urls */)
         {
             //new httpwebrequest
             HttpWebRequest picHttpRequest = WebRequest.CreateHttp(picUrl);
             IAsyncResult picRes = picHttpRequest.BeginGetResponse(DownloadImageResult, picHttpRequest );

       }

    private void DownloadImageResult(IAsyncResult result)
    {
        var res = state.HttpWebRequest;
        var resp = res.EndGetResponse(result);

        /*some saving code*/

        Dispatcher.BeginInvoke(() => { ObrazkiFinal.Add(fileName); });
     }
    }
}

然后在XAML中：

<ListBox Grid.Row="2" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Height="Auto" Name="lBox">
 <ListBox.ItemTemplate>
     <DataTemplate>
        <StackPanel>
              <Image Source="{Binding}"></Image>
        </StackPanel>
     </DataTemplate>
 </ListBox.ItemTemplate>
</ListBox>

当然还有PhoneApplicationPage：

DataContext="{Binding RelativeSource={RelativeSource Self}}"

ObservableCollection在UI线程中成功填充，那么问题是什么？

添加@edit堆栈跟踪：

在MS.Internal.XcpImports.CheckThread（）在System.Windows.DependencyObject.GetValueInternal（DependencyProperty dp）在System.Windows.FrameworkElement.GetValueInternal（DependencyProperty dp）在System.Windows.DependencyObject.GetValue（DependencyProperty dp）在System.Windows.Controls.ItemsControl.get_ItemsSource（）在myPhoneApp.MainPage.DownloadImageResult（IAsyncResult结果）在System.Net.Browser.ClientHttpWebRequest。＆lt;＆gt; c_ DisplayClassa.b _8（Object state2）在System.Threading.ThreadPool.WorkItem.WaitCallback_Context（对象状态）在System.Threading.ExecutionContext.Run（ExecutionContext executionContext，ContextCallback回调，对象状态）在System.Threading.ThreadPool.WorkItem.doWork（Object o）在System.Threading.Timer.ring（）

Answer 1

根据您的堆栈跟踪，DownloadImageResult访问（我假设）ItemsSource的{{1}}属性。删除它或将其移动到ListBox块内。

有关更具体的建议，请发布BeginInvoke功能的完整内容。

在非UI线程中填充ObservableCollection后，WP7中的跨线程访问无效

1 个答案: