flutter使用notification进行父子组件通信

//定义消息盒子
class CustomNotification extends Notification {
  CustomNotification(this.msg);
  final String msg;
}

//在子组件中使用消息盒子发布信息
class CustomChild extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return RaisedButton(
      //按钮点击时分发通知
      onPressed: () => CustomNotification("Hi").dispatch(context),
      child: Text("Fire Notification"),
    );
  }
}



class _MyHomePageState extends State<MyHomePage> {
  String _msg = "通知：";
  @override
  Widget build(BuildContext context) {
    //父组件监听消息，如何监听呢，通过包裹在NotificationListener组件中来实现.
    return NotificationListener<CustomNotification>(
        onNotification: (notification) {
          setState(() {_msg += notification.msg+"  ";});//收到子Widget通知，更新msg
        },
        child:Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[Text(_msg),CustomChild()],//将子Widget加入到视图树中
        )
    );
  }
}