每个消息都有 wParam 和 lParam,如WM_COMMAND,wParam包含两个不同的值,其中: wParam:低字节是控件的id,高字节是通知码 notifyCode lParam: 强制转换为按钮或控件的句柄值 hWndCtl-Each message has wParam and lParam, WM_COMMAND, wParam contains two different values, including: wParam: low byte contr