cocos creator 键盘事件

cc.systemEvent.on(cc.SystemEvent.EventType.KEY_DOWN, this.onKeyboardStart, this);
        cc.systemEvent.on(cc.SystemEvent.EventType.KEY_UP, this.onKeyUpEnd, this);
 
onKeyboardStart(event: cc.Event.EventKeyboard) {
        switch (event.keyCode) {
            case cc.macro.KEY.a:
                break;
            case cc.macro.KEY.d:
                break;
        }
    }
 
onKeyUpEnd(event: cc.Event.EventKeyboard) {
        switch (event.keyCode) {
            case cc.macro.KEY.s:
                break;
            case cc.macro.KEY.space:
                break;
        }
    }