SetWindowsHookEx（
int idHook, // hook type
HOOKPROC lpfn, // hook procedure
HINSTANCE hMod, // handle to application instance
DWORD dwThreadId // thread identifier
）
idHook 赋值为WH_KEYBOARD。
lpfn原型为
LRESULT CALLBACK KeyboardProc(
int code, // hook code
WPARAM wParam, // virtual-key code
LPARAM lParam // keystroke-message information
);
