【Flutter】EventBus简述

EventBus可以实现组件之间的消息通知，这里是讲述其简单应用（点击+- 按钮操作数据）。

1.添加依赖

2.添加数据总线（因为我看过几篇文章说过数据总线声明一个即可，所以我直接证明在main里面了）

3.声明数据总线分类

4.监听事件

5.声明要提交消息的控件

import 'package:flutter/material.dart';
import 'package:flutterdemo0507/eventBusType.dart';
import 'package:flutterdemo0507/main.dart';

class W1 extends StatefulWidget {
  @override
  _W1State createState() => _W1State();
}

class _W1State extends State with SingleTickerProviderStateMixin {
  AnimationController _controller;

  @override
  void initState() {
    _controller = AnimationController(vsync: this);
    super.initState();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        RaisedButton(child: Text('+'),onPressed: (){
          eventBus.fire(EventBus1('+'));
        }),
        RaisedButton(child: Text('-'),onPressed: (){
          eventBus.fire(EventBus1('-'));
        })
      ],
    );
  }
}

6.主页面显示

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State {
  int _count1 = 0;
  int _count2 = 0;

  @override
  void initState() {
    super.initState();
    eventBus.on().listen((event) {
      switch(event.data){
        case '+':
          _count1++;
          break;
        case '-':
          _count1--;
          break;
      }
      setState(() {
      });
    });
    eventBus.on().listen((event) {
      switch(event.data){
        case '+':
          _count2++;
          break;
        case '-':
          _count2--;
          break;
      }
      setState(() {
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('demo'),
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [Text('$_count1'), W1(), Text('$_count2'), W2()],
      ),
    );
  }
}