c# 钩子类

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;

namespace WindowsFormsApplication1
{
    /// <summary>
    /// 键盘Hook管理类

    /// </summary>
    public class KeyboardHookLib
    {
        private const int WH_KEYBOARD_LL = 13; //键盘

        //键盘处理事件委托.
        private delegate int HookHandle(int nCode, int wParam, IntPtr lParam);

        //客户端键盘处理事件
        public delegate void ProcessKeyHandle(HookStruct param, out bool handle);

        //接收SetWindowsHookEx返回值
        private static int _hHookValue = 0;

        //勾子程序处理事件
        private HookHandle _KeyBoardHookProcedure;

        //Hook结构
        [StructLayout(LayoutKind.Sequential)]
        public class HookStruct
        {
            public int vkCode;
            public int scanCode;
            public int flags;
            public int time;
            public int dwExtraInfo;
        }

        //设置钩子
        [DllImport("user32.dll")]
        private static extern int SetWindowsHookEx(int idHook, HookHandle lpfn, IntPtr hInstance, int threadId);

        //取消钩子
        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
        private static extern bool UnhookWindowsHookEx(int idHook);

        //调用下一个钩子
        [DllImport("user32.dll")]
        private static extern int CallNextHookEx(int idHook, int nCode, int wParam, IntPtr lParam);

        //获取当前线程ID
        [DllImport("kernel32.dll")]
        private static extern int GetCurrentThreadId();

        //Gets the main module for the associated process.
        [DllImport("kernel32.dll")]
        private static extern IntPtr GetModuleHandle(string name);

        private IntPtr _hookWindowPtr = IntPtr.Zero;

        //构造器
        public KeyboardHookLib() { }

        //外部调用的键盘处理事件
        private static ProcessKeyHandle _clientMethod = null;

        /// <summary>
        /// 安装勾子
        /// </summary>
        /// <param name="hookProcess">外部调用的键盘处理事件</param>
        public void InstallHook(ProcessKeyHandle clientMethod)
        {
            _clientMethod = clientMethod;

            // 安装键盘钩子
            if (_hHookValue == 0)
            {
                _KeyBoardHookProcedure = new HookHandle(GetHookProc);

                _hookWindowPtr = GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName);

                _hHookValue = SetWindowsHookEx(
                    WH_KEYBOARD_LL,
                    _KeyBoardHookProcedure,
                    _hookWindowPtr,
                    0);

                //如果设置钩子失败.
                if (_hHookValue == 0)

                    UninstallHook();
            }
        }

        //取消钩子事件
        public void UninstallHook()
        {
            if (_hHookValue != 0)
            {
                bool ret = UnhookWindowsHookEx(_hHookValue);
                if (ret) _hHookValue = 0;
            }
        }

        //钩子事件内部调用,调用_clientMethod方法转发到客户端应用。
        private static int GetHookProc(int nCode, int wParam, IntPtr lParam)
        {
            if (nCode >= 0)
            {
                //转换结构
                HookStruct hookStruct = (HookStruct)Marshal.PtrToStructure(lParam, typeof(HookStruct));

                if (_clientMethod != null)
                {
                    bool handle = false;
                    //调用客户提供的事件处理程序。
                    _clientMethod(hookStruct, out handle);
                    if (handle) return 1; //1:表示拦截键盘,return 退出
                }
            }
            return CallNextHookEx(_hHookValue, nCode, wParam, lParam);
        }

    }
}

钩子类使用：

  //钩子管理类
        private KeyboardHookLib _keyBoardHook = null;

        //安装钩子
        private void button5_Click(object sender, EventArgs e)
        {
            _keyBoardHook = new KeyboardHookLib();
            _keyBoardHook.InstallHook(this.KeyPress);

        }

        //取消钩子
        private void button6_Click(object sender, EventArgs e)
        {
            if (_keyBoardHook != null) _keyBoardHook.UninstallHook();
        }


        public void KeyPress(KeyboardHookLib.HookStruct hookStruct, out bool handle)
        {
            handle = false; //预设不拦截任何键

            if (hookStruct.vkCode == 91) // 截获左win(开始菜单键)
            {
                handle = true;
            }

            if (hookStruct.vkCode == 92)// 截获右win
            {
                handle = true;
            }

            //截获Ctrl+Esc
            if (hookStruct.vkCode == (int)Keys.Escape && (int)Control.ModifierKeys == (int)Keys.Control)
            {
                handle = true;
            }

            //截获alt+f4
            if (hookStruct.vkCode == (int)Keys.F4 && (int)Control.ModifierKeys == (int)Keys.Alt)
            {
                handle = true;
            }

            //截获alt+tab
            if (hookStruct.vkCode == (int)Keys.Tab && (int)Control.ModifierKeys == (int)Keys.Alt)
            {
                handle = true;
            }

            //截获F1
            if (hookStruct.vkCode == (int)Keys.F1)
            {
                handle = true;
            }

            //截获Ctrl+Alt+Delete
            if ((int)Control.ModifierKeys == (int)Keys.Control + (int)Keys.Alt + (int)Keys.Delete)
            {
                handle = true;
            }

            //如果键A~Z
            if (hookStruct.vkCode >= (int)Keys.A && hookStruct.vkCode <= (int)Keys.Z)
            {
                //挡掉G键，想要挡掉哪些键就把下面的G换成那个要挡掉的键，同理可以挡多个
                if (hookStruct.vkCode == (int)Keys.G)
                    hookStruct.vkCode = (int)Keys.None; //设键为0

                handle = true;
            }

            Keys key = (Keys)hookStruct.vkCode;
            label1.Text = "你按下:" + (key == Keys.None ? "None" : key.ToString());
        }