我正在使用WPF(MVVM)应用。
使用2个按钮,一个用于从db加载数据,另一个用于删除所选项目。
点击Load
按钮后会触发LoadCommand
并调用StartLoadingThread
private void StartLoadingThread()
{
ShowLoadProcessing(); // show some text on top of screen ("Loading in progress...")
ThreadStart ts = delegate
{
LoadMyitems();
System.Windows.Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (EventHandler)
delegate
{
HideLoadProcessing(); // hide the text "Loading in progress..."
}, null, null);
};
ts.BeginInvoke(ts.EndInvoke, null);
}
工作正常,现在当我选择一个项目并点击Delete
按钮时,DeleteItemCommand
被触发并调用StartDeletingThread
private void StartDeletingThread()
{
ShowDeleteProcessing(); // Show on top of screen "Deleting in progress..."
ThreadStart ts = delegate
{
DeleteSelectedItem();
System.Windows.Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (EventHandler)
delegate
{
HideDeletingProcessing();
}, null, null);
};
ts.BeginInvoke(ts.EndInvoke, null);
}
启动StartDeletingThread
时,我收到以下异常:
{"The calling thread must be STA, because many UI components require this."}
答案 0 :(得分:0)
我认为你想要这样的东西,虽然我在WPF中有点新手,但你必须用WPF(Dispatcher)中的相同内容替换this.BeginInvoke
。代码也可能无法编译(为Thread添加Action
类型转换?),但想法是简单地启动线程(由于某些原因调用它,为什么?)并在该线程中在删除后调用UI操作。
private void StartDeletingThread()
{
ShowDeleteProcessing(); // Show on top of screen "Deleting in progress..."
new Thread(() =>
{
DeleteSelectedItem();
this.BeginInvoke(() => HideDeletingProcessing());
}.Start();
}
答案 1 :(得分:0)
尝试使用应用程序调度程序调用StartDeletingThread,如下所示:
Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal,new
Action(()=>StartDeletingThread())
答案 2 :(得分:0)
private void StartDeletingThread()
{
ShowDeleteProcessing(); // Show on top of screen "Deleting in progress..."
Task.Run(() =>
{
DeleteSelectedItem();
Application.Current.Dispatcher.BeginInvoke((Action)HideDeletingProcessing);
});
}
可能会在DeleteSelectedItem();
爆炸。我知道我们都喜欢为不到一秒钟的动作显示进度条,但是当它导致StackOverflow上的问题时,为什么还要烦恼呢?
private void StartDeletingThread()
{
DeleteSelectedItem();
}
完成并完成。我严重怀疑删除所选项目需要很长时间。
如果在某些极少数情况下确实如此......那么您需要在DeleteSelectedItem
中找到触摸UI的位置,并使用应用程序的调度程序进行触摸。
(旁注,这是你在4.5中安全多线程的方法,使用async / await ... safe,只要你理解async void
的影响,就是这样)
private async void StartDeletingThread()
{
// we're in the UI thread
ShowDeleteProcessing();
await DeleteSelectedItem();
// back in the UI thread
HideDeletingProcessing();
}
private Task DeleteSelectedItem()
{
// doing the work on a Task thread
return Task.Run(() => DeleteSelectedItem = null);
}