步骤

1. 引入第三方库

在 pubspec.yaml 引入 event_bus: ^1.1.1

2. 定义在组件之间传递的对象

class UserInfo {
  String nickname;
  int level;
	
  UserInfo(this.nickname, this.level);
}

3. 创建全局的EventBus对象

final eventBus = EventBus();

4. 在某个widget发出事件

FlatButton(
              child: Text("Testbutton", style: TextStyle(color: Colors.white)),
              color: Colors.orange, // 按钮的颜色

              onPressed: () {
                final info = UserInfo("why", 18);
                eventBus.fire(info);
              },
            ),

5. 在另一个widget监听事件

  @override
  void initState() {
    super.initState();

    eventBus.on().listen((data) {
      setState(() {
        message = "${data.nickname}-${data.level}";
      });
    });
  }

完整代码

import 'package:flutter/material.dart';
import 'package:event_bus/event_bus.dart';

void main() {
  runApp(MyApp());
}

class UserInfo {
  String nickname;
  int level;

  UserInfo(this.nickname, this.level);
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State {
  final eventBus = EventBus();

  String message = "Hello Coderwhy";

  @override
  void initState() {
    super.initState();

    eventBus.on().listen((data) {
      setState(() {
        message = "${data.nickname}-${data.level}";
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              message,
              style: Theme.of(context).textTheme.headline4,
            ),
            FlatButton(
              child: Text("Testbutton", style: TextStyle(color: Colors.white)),
              color: Colors.orange, // 按钮的颜色

              onPressed: () {
                final info = UserInfo("why", 18);
                eventBus.fire(info);
              },
            ),
          ],
        ),
      ),
    );
  }
}