在带有MVVM Light的WP7项目中引发未经授权的AccessException(无效的跨线程访问)

本文关键字：AccessException 授权 无效 访问 线程 MVVM Light WP7 项目 | 更新日期: 2023-09-27 18:22:18

我正在使用MVVM light toolkit的Messenger类来通信我的WP7应用程序的不同部分。

当收到来自应用程序类的消息时，我正试图使视图变为不同的状态。在视图后面的代码中，我注册到消息：

Messenger.Default.Register<PageActionMessage>
(
     this,
    (action) => GoToPage(action)
);

并在收到时调用以下方法：

private object GoToPage(PageActionMessage action)
{
    if (action.action == PageAction.TwitterAuthFinished)
    {
        if (IsoStoreHelper.CheckIfAuthorized())
        {
            VisualStateManager.GoToState(this, "TwitterSendPage", true); // The exception is thrown here
        }
     }
}

在我的另一个班上，消息是这样广播的：

var PageMsg = new PageActionMessage()
{
    action = PageAction.TwitterAuthFinished
};
Messenger.Default.Send<PageActionMessage>(PageMsg);

视图正确接收到此消息，但在调用VisualStateManager的GoToState方法时，会引发UnauthorizedAccessException（无效的跨线程访问），并带有以下跟踪：

System.UnauthorizedAccessException was unhandled
  Message=Invalid cross-thread access.
 StackTrace:
   at MS.Internal.XcpImports.CheckThread()
   at System.Windows.DependencyObject.GetValueInternal(DependencyProperty dp)
   at System.Windows.FrameworkElement.GetValueInternal(DependencyProperty dp)
   at System.Windows.DependencyObject.GetValue(DependencyProperty dp)
   at System.Windows.Controls.Panel.get_Children()
   at MS.Internal.XcpImports.CheckThread()
   at MS.Internal.XcpImports.Control_GetImplementationRoot(Control control)
   at System.Windows.Controls.Control.get_ImplementationRoot()
   at System.Windows.VisualStateManager.GoToState(Control control, String stateName, Boolean useTransitions)
   at KidsBook.MainPage.GoToPage(PageActionMessage action)
   at KidsBook.MainPage.<.ctor>b__0(PageActionMessage action)
   at GalaSoft.MvvmLight.Helpers.WeakAction`1.Execute(PageActionMessage parameter)
   at GalaSoft.MvvmLight.Helpers.WeakAction`1.ExecuteWithObject(Object parameter)
   at GalaSoft.MvvmLight.Messaging.Messenger.SendToList[TMessage](PageActionMessage message, IEnumerable`1 list, Type messageTargetType, Object token)
   at GalaSoft.MvvmLight.Messaging.Messenger.SendToTargetOrType[TMessage](PageActionMessage message, Type messageTargetType, Object token)
   at GalaSoft.MvvmLight.Messaging.Messenger.Send[TMessage](PageActionMessage message)
   at KidsBook.Twitter.OAuthClient.GetResponse(IAsyncResult result)
   at System.Net.Browser.ClientHttpWebRequest.<>c__DisplayClassa.<InvokeGetResponseCallback>b__8(Object state2)
   at System.Threading.ThreadPool.WorkItem.WaitCallback_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadPool.WorkItem.doWork(Object o)
   at System.Threading.Timer.ring()

这是因为什么？提前感谢！

在带有MVVM Light的WP7项目中引发未经授权的AccessException(无效的跨线程访问)

MVVVMLight可以使用DispatcherHelper确保代码在UI线程上运行（您的问题）
例如

DispatcherHelper.CheckBeginInvokeOnUI(YOUR-ACTION);

这是我的解决方案：

http://wp8xp.blogspot.com.es/2013/02/llamadas-asincronas-internet-haciendo.html

Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            });
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