键盘钩子实现代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Reflection;
using System.Runtime.InteropServices;

namespace myHookTest
{
    public partial class frmTest : Form
    {
        public frmTest()
        {
            InitializeComponent();
        }

        //委托
        public delegate int HookProc(int Code, IntPtr wParam, IntPtr lParrm);
        private static int hHook = 0;
        public bool isGo = false;
        public const int WH_KEYBOARD_LL = 13;
        HookProc KeyBoardHookProcedure;//委托对象的实例
        //键盘Hook的结构函数
        [StructLayout(LayoutKind.Sequential)]
        public class KeyBoardHookStruct 
        {
            public int vkCode;
            public int scanCode;
            public int flags;
            public int time;
            public int dwExtraInfo;
        }

        #region 钩子的api函数
        //设置钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, 
            CallingConvention = CallingConvention.StdCall)]
        public static extern int SetWindowsHookEx(int idHook, HookProc lpfn,
            IntPtr hInstance, int threadId);
        //抽调钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto,
            CallingConvention = CallingConvention.StdCall)]
        public static extern bool UnhookWindowsHookEx(int hHook);
        //调用下一个钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto,
            CallingConvention = CallingConvention.StdCall)]
        public static extern int CallNextHookEx(int idCode,
            int nCode, IntPtr wParam, IntPtr lParam);
        #endregion

        //安装钩子
        public void hookStart()
        {
            if (hHook == 0)
            {
                //实例化委托对象
                KeyBoardHookProcedure = new HookProc(keyBoardHookProc);
                hHook = SetWindowsHookEx(WH_KEYBOARD_LL,
                            KeyBoardHookProcedure,
                            Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0);
                //如果抽取钩子失败
                if (hHook == 0)
                {
                    hookClear();
                    this.lblStatus.Text = "设置失败";
                }
            }
        }

        //清除钩子
        public void hookClear()
        {
            bool retKeyBoard = true;
            if (hHook != 0)
            {
                retKeyBoard = UnhookWindowsHookEx(hHook);
                hHook = 0;
            }
            if (!retKeyBoard) this.lblStatus.Text = "抽取失败";
        }

        //处理键盘按下的信息
        public int keyBoardHookProc(int nCode, IntPtr wParam, IntPtr lParam)
        {
            if (nCode >= 0)
            {
                KeyBoardHookStruct kbh = (KeyBoardHookStruct)
                    Marshal.PtrToStructure(lParam, typeof(KeyBoardHookStruct));
                if (!isGo)
                {
                    this.txtKeyBoard.Text += ((char)kbh.vkCode).ToString();
                    isGo = true;
                }
                else
                {
                    isGo = false;
                }
                //if ((int)Control.ModifierKeys==(int)Keys.Control&& kbh.vkCode == (int)Keys.E)
                //{
                //    MessageBox.Show(DateTime.Now.ToShortTimeString());
                //}
                if (this.txtKeyBoard.Text.ToLower() == "iloveyou")
                {
                    MessageBox.Show("Hehe");
                }
            }
            return CallNextHookEx(hHook, nCode, wParam, lParam);
        }

        private void frmTest_Load(object sender, EventArgs e)
        {

        }

        private void btnOpen_Click(object sender, EventArgs e)
        {
            hookStart();//开启钩子
        }

        private void btnClose_Click(object sender, EventArgs e)
        {
            hookClear();//关闭钩子
        }
    }
}

界面图片：