Flutter插件qsub介绍及使用

Flutter插件qsub介绍及使用

qsub 是一个简单的 Flutter 插件，用于订阅 Server-Sent Events (SSE) 协议，如 Mercure。它允许应用接收来自服务器的实时事件更新。

简单示例

以下是一个简单的 Flutter 应用示例，展示了如何使用 qsub 插件来订阅 SSE 事件，并在列表中显示这些事件的数据。

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

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const HomePage(),
    );
  }
}

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

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

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Builder(
        builder: (BuildContext context) {
          return SafeArea(
            child: Column(
              children: <Widget>[
                const Text('Start?'),
                QSub(
                  url: Uri.http(
                    'mercure.pluto.dizoft.ru:8686',
                    '/.well-known/mercure',
                    <String, String>{
                      'topic': 
                          'http://api.pluto.dizoft.ru/subscriptions/369fcd649fdb02ca42e88786a8c52f2156e1063bf1e30a2cc18451632c062ad8',
                    },
                  ),
                  builder: (BuildContext context, List<QSubEvent> events) {
                    return Expanded(
                      child: ListView.builder(
                        itemCount: events.length,
                        itemBuilder: (BuildContext context, int index) {
                          final QSubEvent event = events.elementAt(index);

                          return ListTile(
                            title: Text(
                              event.data ?? '',
                              maxLines: 3,
                              overflow: TextOverflow.ellipsis,
                            ),
                          );
                        },
                      ),
                    );
                  },
                ),
              ],
            ),
          );
        },
      ),
    );
  }
}

代码解释

• 导入库：

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

  导入必要的 Flutter 和 qsub 库。

• 主函数：

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

  定义应用的入口点。

• MyApp 类：

  class MyApp extends StatelessWidget {
    const MyApp({Key? key}) : super(key: key);
  
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: const HomePage(),
      );
    }
  }
  

  定义应用的基本结构，包括主题和初始页面。

• HomePage 类：

  class HomePage extends StatefulWidget {
    const HomePage({
      Key? key,
    }) : super(key: key);
  
    @override
    _HomePageState createState() => _HomePageState();
  }
  

  定义一个有状态的主页，以便管理状态变化。

• _HomePageState 类：

  class _HomePageState extends State<HomePage> {
    @override
    Widget build(BuildContext context) {
      return Scaffold(
        body: Builder(
          builder: (BuildContext context) {
            return SafeArea(
              child: Column(
                children: <Widget>[
                  const Text('Start?'),
                  QSub(
                    url: Uri.http(
                      'mercure.pluto.dizoft.ru:8686',
                      '/.well-known/mercure',
                      <String, String>{
                        'topic': 
                            'http://api.pluto.dizoft.ru/subscriptions/369fcd649fdb02ca42e88786a8c52f2156e1063bf1e30a2cc18451632c062ad8',
                      },
                    ),
                    builder: (BuildContext context, List<QSubEvent> events) {
                      return Expanded(
                        child: ListView.builder(
                          itemCount: events.length,
                          itemBuilder: (BuildContext context, int index) {
                            final QSubEvent event = events.elementAt(index);
  
                            return ListTile(
                              title: Text(
                                event.data ?? '',
                                maxLines: 3,
                                overflow: TextOverflow.ellipsis,
                              ),
                            );
                          },
                        ),
                      );
                    },
                  ),
                ],
              ),
            );
          },
        ),
      );
    }
  }