我正在尝试使用 Task.Factory.StartNew()
运行后台操作。部分后台操作更新保存在 ObservableCollection 中的对象。我正在使用从 ObservableCollection 派生的自定义类来触发 OnCollectionChanged()
当集合中的一个对象的属性发生更改时(请参阅 https://stackoverflow.com/a/5256827/62072 )。如果有 CollectionView
绑定(bind)到 ObservableCollection,那么我会得到一个异常:
System.NotSupportedException: This type of CollectionView does not support changes to its SourceCollection from a thread different from the Dispatcher thread.
我试图避免此异常,因此我添加了一些代码,以便仅在 UI 线程上运行时才触发 OnCollectionChanged()
。但不知何故我仍然得到异常(exception)..
这是我的 ItemPropertyChanged()
方法:
void ItemPropertyChanged(object sender, PropertyChangedEventArgs e)
{
var a = new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Reset);
if (Thread.CurrentThread.ManagedThreadId
== Dispatcher.CurrentDispatcher.Thread.ManagedThreadId)
{
OnCollectionChanged(a);
}
}
这里是完整的异常(exception):
System.AggregateException was unhandled
Message=A Task's exception(s) were not observed either by Waiting on the Task or accessing its Exception property. As a result, the unobserved exception was rethrown by the finalizer thread.
Source=mscorlib
StackTrace:
at System.Threading.Tasks.TaskExceptionHolder.Finalize()
Message=This type of CollectionView does not support changes to its SourceCollection from a thread different from the Dispatcher thread.
InnerException: System.NotSupportedException
Source=PresentationFramework
StackTrace:
at System.Windows.Data.CollectionView.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
at System.Collections.Specialized.NotifyCollectionChangedEventHandler.Invoke(Object sender, NotifyCollectionChangedEventArgs e)
at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
at SourceLog.Model.TrulyObservableCollection`1.ItemPropertyChanged(Object sender, PropertyChangedEventArgs e) in C:\github.com\tomhunter-gh\SourceLog\SourceLog.Model\TrulyObservableCollection.cs:line 41
at System.ComponentModel.PropertyChangedEventHandler.Invoke(Object sender, PropertyChangedEventArgs e)
at SourceLog.Model.LogEntry.OnPropertyChanged(String property) in C:\github.com\tomhunter-gh\SourceLog\SourceLog.Model\LogEntry.cs:line 44
at SourceLog.Model.LogEntry.set_Read(Boolean value) in C:\github.com\tomhunter-gh\SourceLog\SourceLog.Model\LogEntry.cs:line 28
at SourceLog.Model.LogEntry.<MarkAsReadAndSave>b__0() in C:\github.com\tomhunter-gh\SourceLog\SourceLog.Model\LogEntry.cs:line 53
at System.Threading.Tasks.Task.InnerInvoke()
at System.Threading.Tasks.Task.Execute()
InnerException:
为什么异常会提示我不在 Dispatcher 线程上,而我已明确检查过我在 Dispatcher 线程上?
最佳答案
Dispatcher.CurrentDispatcher
与 UI 线程无关,正如该属性的名称所暗示的那样,它为您提供了当前线程的调度程序。因此,您创建了一个始终返回 true 的检查。使用 Application.Current.Dispatcher
,也可以在所述调度程序上调用它而不是忽略更改。
关于c# - 检查 Dispatcher.CurrentDispatcher.Thread.ManagedThreadId 后的 CollectionView NotSupportedException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12110740/