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 = ; //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 = ;

         //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 == )
             {
                 _KeyBoardHookProcedure = new HookHandle(GetHookProc);

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

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

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

                     UninstallHook();
             }
         }

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

         //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 >= )
             {
                 //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: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 == ) // 截获左win(开始菜单键)
             {
                 handle = true;
             }

             if (hookStruct.vkCode == )// 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());
         }