Question

我有一个控制台应用程序，提示用户输入多个输入。我希望用户能够在任何提示取消操作后按下转义。

类似的东西：

if (Console.ReadKey().Key != ConsoleKey.Escape) {
  string input = Console.ReadLine();
  ...
}

然而，问题是，如果按下除了escape之外的键，它将不是输入的一部分（从ReadLine返回）。

有没有办法“偷看”下一把钥匙，否则就这样做？

Answer 1

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
internal struct InputRecord
{
  internal short eventType;
  internal KeyEventRecord keyEvent;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
internal struct KeyEventRecord
{
  internal bool keyDown;
  internal short repeatCount;
  internal short virtualKeyCode;
  internal short virtualScanCode;
  internal char uChar;
  internal int controlKeyState;
}

[DllImport("kernel32.dll", SetLastError = true)]
internal static extern bool PeekConsoleInput(IntPtr hConsoleInput, out InputRecord buffer, int numInputRecords_UseOne, out int numEventsRead);

[DllImport("kernel32.dll", SetLastError = true)]
internal static extern bool ReadConsoleInput(IntPtr hConsoleInput, out InputRecord buffer, int numInputRecords_UseOne, out int numEventsRead);

[DllImport("kernel32.dll", SetLastError = true)]
internal static extern IntPtr GetStdHandle(int nStdHandle);

static Nullable<InputRecord> PeekConsoleEvent()
{
  InputRecord ir;
  int num;
  if (!PeekConsoleInput(GetStdHandle(-10), out ir, 1, out num))
  {
    //TODO process error
  }
  if (num != 0)
    return ir;
  return null;
}
static InputRecord ReadConsoleInput()
{
  InputRecord ir;
  int num;
  if (!ReadConsoleInput(GetStdHandle(-10), out ir, 1, out num))
  {
    //TODO process error
  }
  return ir;
}
static bool PeekEscapeKey()
{
  for (; ; )
  {
    var ev = PeekConsoleEvent();
    if (ev == null)
    {
      Thread.Sleep(10);
      continue;
    }
    if (ev.Value.eventType == 1 && ev.Value.keyEvent.keyDown && ev.Value.keyEvent.virtualKeyCode == 27)
    {
      ReadConsoleInput();
      return true;
    }
    if (ev.Value.eventType == 1 && ev.Value.keyEvent.keyDown)
      return false;
    ReadConsoleInput();
  }
}

用法示例：

  for (; ; )
  {
    Console.Write("?");
    if (PeekEscapeKey())
    {
      Console.WriteLine("esc");          
      continue;
    }
    Console.Write(">");
    var line = Console.ReadLine();
    Console.WriteLine(line);
  }

Answer 2

要窥视，您必须使用TextReader.Peek。要在控制台中使用它，您可以使用Console.In.Peek()。要使用您正在考虑的代码：

if(Console.In.Peek() != "\0x1B") // 0x1B is the Escape Key
{
        string input = Console.ReadLine();
        ....
}

这应该有效。我没有测试过，但似乎没错。

Answer 3

或者用于比@ user823682

更不优雅的方法

ConsoleKeyInfo key = Console.ReadKey().Key;
if (key != ConsoleKey.Escape) {
  string input = String.Concat(key.KeyChar,Console.ReadLine());
  ...
}

拦截ESC而不从缓冲区中删除其他按键

3 个答案: