VC/MFC 键盘钩子，代码片断

[code=plain]在MFC程序中使用键盘钩子来获取按键消息，例程：

[code=plain]#include "StdAfx.h"
#include "KeyboardHook.h"
static HHOOK g_hHook = NULL;
static CWnd* g_pWnd  = NULL;

BOOL CKeyboardHook::Init(HINSTANCE hInst, CWnd *pWnd)
{
g_pWnd = pWnd;
g_hHook = SetWindowsHookEx(WH_KEYBOARD_LL,CKeyboardHook::KeyboardHookProc,hInst,NULL);
return g_hHook == NULL ? FALSE : TRUE;
}

void CKeyboardHook::Close()
{
UnhookWindowsHookEx(g_hHook);
}

LRESULT CALLBACK CKeyboardHook::KeyboardHookProc(int code, WPARAM wParam, LPARAM lParam)
{
if(code == HC_ACTION)
{
PKBDLLHOOKSTRUCT pStruct = (PKBDLLHOOKSTRUCT)lParam;
switch(pStruct->vkCode)
{
case 'a':
case 'A':
case 's':
case 'S':
case 'd':
case 'D':
case 'j':
case 'J':
case ' ':
if (wParam == WM_KEYDOWN)
{
g_pWnd->PostMessage(WM_KEYDOWN, pStruct->vkCode, pStruct->scanCode);
}
return TRUE;
break;
default:  return CallNextHookEx(g_hHook, code, wParam, lParam);
}
}
return CallNextHookEx(g_hHook, code, wParam, lParam);
}