Flutter事件总线插件zevent_bus的使用

EventBus简介

zevent_bus 是一个用于在 Flutter 应用中实现事件总线功能的简单工具。它允许组件之间通过发布-订阅模式进行通信，而无需直接依赖于父组件或子组件。

使用方法

1. 添加依赖

首先，在 pubspec.yaml 文件中添加 zevent_bus 依赖：

dependencies:
  zevent_bus: ^版本号

然后运行以下命令以更新依赖项：

flutter pub get

2. 创建事件监听器

示例代码：创建一个 _Text 组件，用于接收事件并更新 UI

class _Text extends StatefulWidget {
  const _Text({Key? key}) : super(key: key);

  [@override](/user/override)
  __TextState createState() => __TextState();
}

class __TextState extends State<_Text> {
  String val = ""; // 用于存储接收到的事件参数
  EventRemoveCallback? _eventRemoveCallback; // 用于移除事件监听器

  [@override](/user/override)
  void initState() {
    super.initState();
    // 注册事件监听器
    _eventRemoveCallback = EventBus.instance.addListener(
      eventKey: "CUS_KEY", // 定义事件标识符
      callback: (arg) { // 回调函数处理事件参数
        setState(() {
          val = "$arg"; // 更新 UI
        });
      },
    );
  }

  [@override](/user/override)
  void dispose() {
    // 在组件销毁时移除事件监听器
    _eventRemoveCallback?.call();
    super.dispose();
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Text(
      '$val', // 显示接收到的事件参数
      style: Theme.of(context).textTheme.headline4,
    );
  }
}

3. 发布事件

示例代码：在按钮点击时发布事件

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

  final String title;

  [@override](/user/override)
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    _counter += 1;
    // 发布事件，传递参数
    EventBus.instance.commit(eventKey: "CUS_KEY", arg: "params = $_counter");
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            _Text(), // 显示事件参数
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

4. 完整示例代码

以下是完整的示例代码，展示如何结合事件总线进行组件间的通信：

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

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

const String CUS_KEY = "CUS_KEY";

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  final String title;

  [@override](/user/override)
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    _counter += 1;
    EventBus.instance.commit(eventKey: CUS_KEY, arg: "params = $_counter");
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            _Text(),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

class _Text extends StatefulWidget {
  const _Text({Key? key}) : super(key: key);

  [@override](/user/override)
  __TextState createState() => __TextState();
}

class __TextState extends State<_Text> {
  String val = "";
  EventRemoveCallback? _eventRemoveCallback;

  [@override](/user/override)
  void initState() {
    super.initState();
    // 注册事件监听器
    _eventRemoveCallback = EventBus.instance.addListener(
      eventKey: CUS_KEY,
      callback: (arg) {
        setState(() {
          val = "$arg";
        });
      },
    );
  }

  [@override](/user/override)
  void dispose() {
    // 移除事件监听器
    _eventRemoveCallback?.call();
    super.dispose();
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Text(
      '$val',
      style: Theme.of(context).textTheme.headline4,
    );
  }
}