键盘勾子程序

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 hook;
namespace hook
{
    public partial class Form1 : Form
    {
        private hook.KeyboardHookLib _keyboardHook = null;

         public Form1()
      {
         InitializeComponent();
      }

         int num = 0;
      private void button1_Click(object sender, EventArgs e)
      {
         //安装勾子 
         _keyboardHook = new hook.KeyboardHookLib();
         _keyboardHook.InstallHook(this.OnKeyPress);
      }
      
      private void button2_Click(object sender, EventArgs e)
      {
         //取消勾子 
         if (_keyboardHook != null) _keyboardHook.UninstallHook();
      }
      
      /// <summary> 
      /// 客户端键盘捕捉事件. 
      /// </summary> 
      /// <param name="hookStruct">由Hook程序发送的按键信息</param> 
      /// <param name="handle">是否拦截</param> 
      public void OnKeyPress(hook.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B键 
            if (hookStruct.vkCode == (int)Keys.B)
            hookStruct.vkCode = (int)Keys.None; //设键为0 
            
            handle = true;
         }
         
         Keys key = (Keys)hookStruct.vkCode;
         num++;
         label1.Text = "你按下:" + (key == Keys.None ? "" : key.ToString())+"   按下次数是："+num.ToString();
         
      }
   }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Reflection;
using System.Diagnostics;
using Microsoft.Win32;
using System.Windows.Forms;

 namespace hook
{
   /// <summary> 
   /// 键盘Hook管理类, by www.vjsdn.com 易学原创 
   /// </summary> 
   public class KeyboardHookLib
   {
      private const int WH_KEYBOARD_LL = 13; //键盘 
      
      //键盘处理事件委托 ,当捕获键盘输入时调用定义该委托的方法. 
      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(OnHookProc);
            
            _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 OnHookProc(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);
      }
      
   }
}
//如果其他的窗口输入的东西都被截止了，只要将OnKeyPress（）事件中所有的截获操作注释掉，就可以正常使用了。