检测是否在 WPF 和 Winforms 中的 UI 线程上 [英] Detecting whether on UI thread in WPF and Winforms

问题描述

我在下面编写了一个断言方法 Ensure.CurrentlyOnUiThread()，用于检查当前线程是否为 UI 线程.

I've written an assertion method Ensure.CurrentlyOnUiThread(), below, that checks that the current thread is a UI thread.

• 这在检测 Winforms UI 线程时是否可靠?
• 我们的应用混合了 WPF 和 Winform，如何最好地检测有效的 WPF UI 线程?
• 有没有更好的方法来做到这一点?也许代码契约?

Ensure.cs

using System.Diagnostics;
using System.Windows.Forms;

public static class Ensure
{
    [Conditional("DEBUG")]
    public static void CurrentlyOnUiThread()
    {
        if (!Application.MessageLoop)
        {
            throw new ThreadStateException("Assertion failed: not on the UI thread");
        }
    }
}

推荐答案

请勿使用

if(Dispatcher.CurrentDispatcher.Thread == Thread.CurrentThread)
{
   // Do something
}

Dispatcher.CurrentDispatcher 将，如果当前线程没有调度器，则创建并返回一个与当前线程关联的新 Dispatcher.

Dispatcher.CurrentDispatcher will, if the current thread do not have a dispatcher, create and return a new Dispatcher associated with the current thread.

改为这样做

Dispatcher dispatcher = Dispatcher.FromThread(Thread.CurrentThread);
if (dispatcher != null)
{
   // We know the thread have a dispatcher that we can use.
}

为了确保您有正确的调度员或在正确的线程上，您有以下选项

To be sure you have the correct dispatcher or are on the correct thread you have the following options

Dispatcher _myDispatcher;

public void UnknownThreadCalling()
{
    if (_myDispatcher.CheckAccess())
    {
        // Calling thread is associated with the Dispatcher
    }

    try
    {
        _myDispatcher.VerifyAccess();

        // Calling thread is associated with the Dispatcher
    }
    catch (InvalidOperationException)
    {
        // Thread can't use dispatcher
    }
}

CheckAccess() 和 VerifyAccess() 没有出现在智能感知中.

CheckAccess() and VerifyAccess() do not show up in intellisense.

此外，如果您不得不求助于这些类型的东西，很可能是由于设计不当.您应该知道哪些线程在您的程序中运行哪些代码.

Also, if you have to resort to these kinds of things its likely due to bad design. You should know which threads run what code in your program.

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