VC/MFC 键盘钩子，代码片断

在MFC程序中使用键盘钩子来获取按键消息，例程：

#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);
}