我正在尝试创建一个自定义的内部应用程序,该应用程序将访问其他内部系统,这些内部系统通过UDP广播其名称和IP地址.我正在尝试创建一个多线程对话框,该对话框每500毫秒轮询一次UDP消息,持续15秒,解析UDP消息,然后将检测到的系统的名称添加到对话框中的列表框,以实时更新它.我已经测试并完成了UDP扫描代码,唯一的问题是跨线程更新ListBox.每当我尝试访问ListBox的Items或ItemSource属性时,都会得到System.InvalidOperationException:调用线程无法访问此对象,因为另一个线程拥有它."
I'm trying to create a custom, in-house application that is going to access other internal systems which broadcast their names and IP addresses via UDP. I'm trying to create a multi-threaded dialog that polls for UDP messages every 500 ms for 15 seconds, parses the UDP messages and then adds the names of the detected systems to a ListBox in the dialog, updating it in real time. I've already got the UDP scanning code tested and done, the only problem is updating the ListBox across threads. Any time I try to access the ListBox's Items or ItemSource properties, I get a System.InvalidOperationException : "The calling thread cannot access this object because a different thread owns it."
相关的堆栈跟踪部分:
at System.Windows.Threading.Dispatcher.VerifyAccess() at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value) at System.Windows.Controls.ItemsControl.set_ItemsSource(IEnumerable value)无论我是否使用ObservableCollection(我知道,与集合类型无关),HashSet或任何其他对象,都将发生这种情况.有人可以帮助我在不同线程之间访问GUI吗?
This occurs regardless of whether I'm using an ObservableCollection (I know, has nothing to do with the collection type), a HashSet or any other object. Can anybody help me with accessing the GUI across different threads ?
推荐答案您不能从其他线程安全地访问gui.所有调用都必须通过对Invoke的调用来分派,以在主线程上执行.这是Windows困扰多年的遗留问题.
You can't access the gui safely from other threads. All calls have to be dispatched via a call to Invoke to be executed on the main thread. This is a legacy hang-up that Windows has been saddled with for years.
这是一段代码,应该可以让您入门... (在此处找到: http: //social.msdn.microsoft/forums/zh-CN/wpf/thread/360540eb-d756-4434-86f9-a3449f05eb55/)
Here's a snippet of code that should get you started... (found here: social.msdn.microsoft/forums/en-US/wpf/thread/360540eb-d756-4434-86f9-a3449f05eb55/ )
if(textbox.Dispatcher.CheckAccess()) { // The calling thread owns the dispatcher, and hence the UI element textbox.AppendText(...); } else { // Invokation required textbox.Dispatcher.Invoke(DispatcherPriority.Normal, [delegate goes here]); }此处还有其他说明: channel9.msdn/forums/TechOff/251835-WPF-Invoke-and-Anonymous-delegates/
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