NotificationAbout.dart

import 'package:flutter/material.dart';
import 'package:flutter_starter_notes/component/CommonTitle.dart';

class NotificationAbout extends StatelessWidget {
  NotificationAbout({Key key, this.title});

  final String title;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(title),
      ),
      body: SingleChildScrollView(
        child: Column(
          children: <Widget>[
            CommonTitle('Notification 介绍'),
            Container(
              padding: EdgeInsets.all(16),
              child: Text(
                  """Notification是Flutter中一个重要的机制，在Widget树中，每一个节点都可以分发通知，通知会沿着当前节点（context）向上传递，所有父节点都可以通过NotificationListener来监听通知，Flutter中称这种通知由子向父的传递为“通知冒泡”（Notification Bubbling），这个和用户触摸事件冒泡是相似的，但有一点不同：通知冒泡可以中止，但用户触摸事件不行。"""),
            ),
            CommonTitle('Notification 示例'),
            Container(
              color: Colors.grey,
              height: 200,
              child: NotificationListener(
                onNotification: (notification) {
                  //print(notification);
                  switch (notification.runtimeType) {
                    case ScrollStartNotification:
                      print("开始滚动");
                      break;
                    case ScrollUpdateNotification:
                      print("正在滚动");
                      break;
                    case ScrollEndNotification:
                      print("滚动停止");
                      break;
                    case OverscrollNotification:
                      print("滚动到边界");
                      break;
                  }
                },
                child: ListView.builder(
                    itemCount: 100,
                    itemBuilder: (context, index) {
                      return ListTile(
                        title: Text("$index"),
                      );
                    }),
              ),
            ),
            CommonTitle('自定义通知'),
            NotificationRoute()
          ],
        ),
      ),
    );
  }
}


class NotificationRoute extends StatefulWidget {
  @override
  NotificationRouteState createState() {
    return new NotificationRouteState();
  }
}

class NotificationRouteState extends State<NotificationRoute> {
  String _msg="";
  @override
  Widget build(BuildContext context) {
    //监听通知
    return NotificationListener<MyNotification>(
      onNotification: (notification) {
        setState(() {
          _msg+=notification.msg+"  ";
        });
      },
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
//          RaisedButton(
//           onPressed: () => MyNotification("Hi").dispatch(context),
//           child: Text("Send Notification"),
//          ),
            Builder(
              builder: (context) {
                return RaisedButton(
                  //按钮点击时分发通知
                  onPressed: () => MyNotification("Hi").dispatch(context),
                  child: Text("Send Notification"),
                );
              },
            ),
            Text(_msg)
          ],
        ),
      ),
    );
  }
}

class MyNotification extends Notification {
  MyNotification(this.msg);
  final String msg;
}