如何使用Win32调用在C#中关闭/打开控制台？

Question

以下程序在"Console.ReadKey()"上引发错误.

禁用后如何重新启用控制台？

    using System;
    using System.Threading;
    using System.Runtime.InteropServices;

    namespace ConsoleApplication
    {
        class Program
        {
            static void Main(string[] args)
            {
                ThreadPool.QueueUserWorkItem((o) =>
                {
                    Thread.Sleep(1000);
                    IntPtr stdin = GetStdHandle(StdHandle.Stdin);
                    CloseHandle(stdin);
                });
                Console.ReadLine();
                Console.Write("ReadLine() successfully aborted by background thread.\n");
                Console.Write("[any key to exit]");
                Console.ReadKey(); // Throws an exception "Cannot read keys when either application does not have a console or when console input has been redirected from a file. Try Console.Read."
            }

            // P/Invoke:
            private enum StdHandle { Stdin = -10, Stdout = -11, Stderr = -12 };
            [DllImport("kernel32.dll")]
            private static extern IntPtr GetStdHandle(StdHandle std);
            [DllImport("kernel32.dll")]
            private static extern bool CloseHandle(IntPtr hdl);
        }
    }

专家额外

如果您想知道,我需要能够在C#中杀死运行ReadLine()的后台线程.这似乎是唯一的方法(thread.Abort将无法工作,因为ReadLine()在操作系统的内部深处运行,在非托管代码中).在StackOverflow上有很多关于这个主题的讨论,没有人真正发现(或发布)一个令人满意的中止Console.ReadLine()的方法.我认为这段代码是正确的 - 如果只有我们可以在禁用它后重新启用它.

Answer 1

使用PostMessage将[enter]发送到当前进程:

    class Program
    {
        [DllImport("User32.Dll", EntryPoint = "PostMessageA")]
        private static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);

        const int VK_RETURN = 0x0D;
        const int WM_KEYDOWN = 0x100;

        static void Main(string[] args)
        {
            Console.Write("Switch focus to another window now to verify this works in a background process.\n");

            ThreadPool.QueueUserWorkItem((o) =>
            {
                Thread.Sleep(4000);

                var hWnd = System.Diagnostics.Process.GetCurrentProcess().MainWindowHandle;
                PostMessage(hWnd, WM_KEYDOWN, VK_RETURN, 0);
            });

            Console.ReadLine();

            Console.Write("ReadLine() successfully aborted by background thread.\n");
            Console.Write("[any key to exit]");
            Console.ReadKey();
        }
    }

这个答案也解决了这样一个事实,即在ReadLine()上调用.Abort将无法工作,因为代码在Windows内核深处的非托管代码中运行.

这个答案优于任何仅在当前进程具有焦点时才有效的答案,例如SendKeys和Input Simulator.

这个答案优于关闭当前控制台句柄的方法,因为关闭当前控制台句柄的行为导致将来调用ReadLine()抛出错误.

Answer 2

不知道它是否有帮助，但是当我需要能够在 win 表单应用程序中写入控制台时，我使用了此类：

public class ConsoleHelper
{
    /// <summary>
    /// Allocates a new console for current process.
    /// </summary>
    [DllImport("kernel32.dll")]
    public static extern Boolean AllocConsole();

    /// <summary>
    /// Frees the console.
    /// </summary>
    [DllImport("kernel32.dll")]
    public static extern Boolean FreeConsole();
}

调用 AllocConsole 创建一个控制台，然后您可以对其进行写入（和读取）。完成后，然后调用 FreeConsole。