在控制台应用程序中等待键盘事件

Question

有没有办法在没有专用线程的情况下获得完成的 Task 和 returns 按键？

// Kernel callback, not a new thread in my process waiting for a keyboard event
var key = await KeyPress();

因为 Console.ReadKey() 是一个阻塞调用，只使用一个线程来等待用户输入。

Answer 1

您可以打开标准输入流，其中有读取的异步操作：

using (var stream = Console.OpenStandardInput())
{
    var buffer = new byte[1];
    var bytesRead = await stream.ReadAsync(buffer, 0, 1);
    char c = (char)buffer[0];
    Console.WriteLine(c);
}

Answer 2

that is the thing, a thread dedicated only to wait for user input sounds like a waste (not necessarily a big one, but it feels like it should have an implementation for this).

对于需要用户输入的控制台应用程序，我不会担心这一点。

无论如何，通过使用一些底层 Win32 API，可能可以实现您的目标。 ReadConsoleInput 的文档说：

A process can specify a console input buffer handle in one of the wait functions to determine when there is unread console input. When the input buffer is not empty, the state of a console input buffer handle is signaled. To determine the number of unread input records in a console's input buffer, use the GetNumberOfConsoleInputEvents function. To read input records from a console input buffer without affecting the number of unread records, use the PeekConsoleInput function. To discard all unread records in a console's input buffer, use the FlushConsoleInputBuffer function.

因此，理论上，您可以使用 GetStdHandle 返回的句柄并将其传递给 RegisterWaitForSingleObject. Then you could convert it to an awaitable task using TaskCompletionSource, e.g. as described here。

这个我没有在实践中验证过。它不应该阻塞线程，但 IMO，再一次，游戏不值得。

在控制台应用程序中等待键盘事件

Await keyboard event in a Console application

c#

async-await