钩子示例

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Reflection;
using System.IO;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public delegate IntPtr HookProc(int code, IntPtr wparam, IntPtr lparam);

    public enum HookType //枚举，钩子的类型 WindowsMessageHook
    {
        MsgFilter = -1,
        JournalRecord = 0,
        JournalPlayback = 1,
        Keyboard = 2,
        GetMessage = 3,
        CallWndProc = 4,
        CBT = 5,
        SysMsgFilter = 6,
        Mouse = 7,
        Hardware = 8,
        Debug = 9,
        Shell = 10,
        ForegroundIdle = 11,
        CallWndProcRet = 12,
        KeyboardLL = 13,
        MouseLL = 14
    }

    [StructLayout(LayoutKind.Sequential)]
    public class KeyboardHookStruct
    {
        public int vkCode; //表示一个在1到254间的虚似键盘码
        public int scanCode; //表示硬件扫描码
        public int flags;
        public int time;
        public int dwExtraInfo;
    }

    public class KeyboardHook
    {
        private const int WM_KEYDOWN = 0x100;
        private const int WM_KEYUP = 0x101;

        private IntPtr nextHookPtr; //记录Hook编号 
        private HookProc hookProc;

        [DllImport("User32.dll")]
        public static extern void UnhookWindowsHookEx(IntPtr handle);
        [DllImport("User32.dll")]
        public static extern IntPtr SetWindowsHookEx(int idHook, [MarshalAs(UnmanagedType.FunctionPtr)] HookProc lpfn, IntPtr hinstance, int threadID);
        [DllImport("User32.dll")]
        public static extern IntPtr CallNextHookEx(IntPtr handle, int code, IntPtr wparam, IntPtr lparam);

        public KeyboardHook()
        {
            nextHookPtr = IntPtr.Zero;
        }

        public void SetKeyboardHook()
        {
            if (nextHookPtr != IntPtr.Zero)
                return;
            hookProc = new HookProc(KeyboardhookProc); //键盘事件消息处理函数         
            nextHookPtr = SetWindowsHookEx((int)HookType.KeyboardLL,
                                            hookProc,
                                            Marshal.GetHINSTANCE(
                                            Assembly.GetExecutingAssembly().GetModules()[0]), 0);
        }

        public void UnKeyboardHook()
        {

            if (nextHookPtr != IntPtr.Zero)
            {
                UnhookWindowsHookEx(nextHookPtr); //从Hook链中取消
                nextHookPtr = IntPtr.Zero;
            }
        }

        private IntPtr KeyboardhookProc(int code, IntPtr wparam, IntPtr lparam)
        {
            if (code >= 0)
            {
                KeyboardHookStruct myKeyboardHookStruct = (KeyboardHookStruct)Marshal.PtrToStructure(lparam, typeof(KeyboardHookStruct));
                switch (wparam.ToInt32())
                {
                    case WM_KEYDOWN:
                        Console.Write(string.Format("{0}", Convert.ToChar(myKeyboardHookStruct.vkCode)));
                        break;
                    case WM_KEYUP:
                        //Console.WriteLine(string.Format("WM_KEYUP:{0:0}", Convert.ToChar(myKeyboardHookStruct.vkCode)));
                        break;
                    default:
                        break;
                }
            }
            return CallNextHookEx(nextHookPtr, code, wparam, lparam); //返回，让后面的程序处理该消息
        }
    }
}