深入分析C#键盘勾子(Hook),屏蔽键盘活动的详解

LRESULT CALLBACKHookProc
(
int nCode,
      WPARAM wParam,
      LPARAM lParam
);

HHOOKSetWindowsHookEx(
int idHook,      // 钩子的类型，即它处理的消息类型
HOOKPROC lpfn,   // 钩子子程的地址指针。如果dwThreadId参数为0
      // 或是一个由别的进程创建的线程的标识，
      // lpfn必须指向DLL中的钩子子程。
      // 除此以外，lpfn可以指向当前进程的一段钩子子程代码。
      // 钩子函数的入口地址，当钩子钩到任何消息后便调用这个函数。
HINSTANCE hMod, // 应用程序实例的句柄。标识包含lpfn所指的子程的
DLL。
      // 如果dwThreadId 标识当前进程创建的一个线程，
      // 而且子程代码位于当前进程，hMod必须为NULL。
      // 可以很简单的设定其为本应用程序的实例句柄。
DWORD dwThreadId // 与安装的钩子子程相关联的线程的标识符。
      // 如果为0，钩子子程与所有的线程关联，即为全局钩子。
            );

LRESULTCallNextHookEx
   (
    HHOOK hhk;
    int nCode;
    WPARAM wParam;
    LPARAM lParam;
    );

UnHookWindowsHookEx
(
HHOOK hhk;
);

#pragmadata_seg("SharedDataName")
HHOOK hHook=NULL;
#pragma data_seg()

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Reflection;
using System.Diagnostics;
using Microsoft.Win32;
namespace Vjsdn.Tech.KeyboardHook
{
   public partial class frmKeyboardHook : Form
   {
      //勾子管理类
      private KeyboardHookLib _keyboardHook = null;
     
      public frmKeyboardHook()
      {
         InitializeComponent();
      }
     
      private void button1_Click(object sender, EventArgs e)
      {
         //安装勾子
         _keyboardHook = new 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</param>
      public void OnKeyPress(KeyboardHookLib.HookStruct hookStruct, out bool handle)
      {
         handle = false; //预设不任何键
        
         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;
         label1.Text = "你按下:" + (key == Keys.None ? "" : key.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 Vjsdn.Tech.KeyboardHook
{
   /// <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
     
      //键盘处理事件托 ,当捕获键盘输入时调用定义该托的方法.
      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:表示键盘,return 退出
            }
         }
         return CallNextHookEx(_hHookValue, nCode, wParam, lParam);
      }
     
   }
}