HOOK使用:全局键盘钩子

 // CatchKey.cpp : Defines the entry point for the DLL application.
 //

 #define _WIN32_WINNT  0x0500        //设置系统版本，可以使用底层键盘钩子
 #define WM_MY_SHORTS (WM_USER + 105)
 #include "windows.h"
 //全局变量
 LPWORD      g_lpdwVirtualKey = NULL;    //Keycode 数组的指针
 int         g_nLength = 0;          //Keycode 数组的大小
 HINSTANCE   g_hInstance = NULL;     //模块实例句柄
 HHOOK       g_hHook = NULL;         //钩子句柄
 HWND        g_hWnd  = NULL;


 BOOL APIENTRY DllMain(HANDLE hModule, DWORD  ul_reason_for_call,LPVOID lpReserved)
 {
     //保存模块实例句柄
     g_hInstance = (HINSTANCE)hModule;

     //在进程结束或线程结束时卸载钩子
     switch (ul_reason_for_call)
     {
     case DLL_PROCESS_ATTACH:
            break;
     case DLL_THREAD_ATTACH:
          break;
     case DLL_PROCESS_DETACH:
       case DLL_THREAD_DETACH:
         delete g_lpdwVirtualKey;
         if (g_hHook != NULL) UnhookWindowsHookEx(g_hHook);
         break;
     }
     return TRUE;
 }

 LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam,LPARAM lParam)
 {
     //判断是否是有效按键
     if (nCode >= HC_ACTION && wParam==WM_KEYDOWN)
     {
         BOOL bctrl = GetAsyncKeyState(VK_CONTROL)>>((sizeof(SHORT) *8)-1);
         KBDLLHOOKSTRUCT* pStruct = (KBDLLHOOKSTRUCT*)lParam;
         LPWORD tmpVirtualKey = g_lpdwVirtualKey;
         if (pStruct->vkCode == 80 && bctrl)
             PostMessage(g_hWnd,WM_MY_SHORTS,0,1);
         return TRUE;
     }
     //传给系统中的下一个钩子
     return CallNextHookEx(g_hHook, nCode, wParam, lParam);
 }

  _declspec(dllexport)
 BOOL WINAPI StartCatch(LPWORD lpdwVirtualKey, int nLength,  HWND  pWnd)
 {
     g_hWnd = pWnd;
     //如果已经安装键盘钩子则返回 FALSE
     if (g_hHook != NULL) return FALSE;
     //将用户传来的 keycode 数组保存在全局变量中
     g_lpdwVirtualKey = (LPWORD)malloc(sizeof(WORD) * nLength);
     LPWORD tmpVirtualKey = g_lpdwVirtualKey;
     for (int i = 0; i < nLength; i++)
     {
         *tmpVirtualKey++ = *lpdwVirtualKey++;
     }
     g_nLength = nLength;
     //安装底层键盘钩子
     g_hHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc,  g_hInstance, NULL);
     if (g_hHook == NULL) return FALSE;
     return TRUE;
 }

  _declspec(dllexport)
 BOOL WINAPI StopCatch()
 {   //卸载钩子
     if (UnhookWindowsHookEx(g_hHook) == 0) return FALSE;
     g_hHook = NULL;
     return TRUE;
  }

 

利用底层的键盘钩子 
LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam,LPARAM lParam)
来拦截 按键的时候

键盘的键按下和弹起时候会发生WM_KEYUP 和 WM_KEYDOWN两个消息，
这两个消息都会被hook，所以如此。

所以需要对 wParam 进行判断  是 WM_KEYDOWN 还是 WM_KEYUP