一个dos下的hook

using System;
using System.Runtime.InteropServices; //调用外部dll的命名空间
delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam);
class Test
{
[DllImport("user32.dll", CharSet=CharSet.Auto)]
static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hMod, int dwThreadId);

[DllImport("user32.dll")]
static extern bool UnhookWindowsHookEx(IntPtr hhk);

[DllImport("user32.dll")]
static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

const int WH_KEYBOARD_LL = 13;

static IntPtr hook;

static void Main()
{
  // Warning - this means trouble!
  hook = SetWindowsHookEx( WH_KEYBOARD_LL, new HookProc(MyLLKbdProc),
                           Marshal.GetHINSTANCE( typeof(Test).Module ), 0 );
  // GC.Collect();
  System.Windows.Forms.MessageBox.Show( "Press OK to cancel hook and exit." );
  UnhookWindowsHookEx( hook );
}

static IntPtr MyLLKbdProc(int nCode, IntPtr wParam, IntPtr lParam)
{
  Console.WriteLine( "message: {0}, vk: {1}", (int)wParam, Marshal.ReadInt32( lParam ) );
  return CallNextHookEx( hook, nCode, wParam, lParam );
}
}