Question

每当我禁用Internet连接时，我的应用程序（实际上是从here提取的）就会崩溃，就像互联网的魅力一样。我如何仍然能够访问页面，显示上次访问的结果而不会卡住？我在清单中包含了所有互联网许可。

<uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

这是代码

import 'dart:async';
import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

Future<Album> fetchAlbum() async {
  final response =
      await http.get('https://jsonplaceholder.typicode.com/albums/1');

  if (response.statusCode == 200) {
    // If the server did return a 200 OK response, then parse the JSON.
    return Album.fromJson(json.decode(response.body));
  } else {
    // If the server did not return a 200 OK response, then throw an exception.
    throw Exception('Failed to load album');
  }
}

class Album {
  final int userId;
  final int id;
  final String title;

  Album({this.userId, this.id, this.title});

  factory Album.fromJson(Map<String, dynamic> json) {
    return Album(
      userId: json['userId'],
      id: json['id'],
      title: json['title'],
    );
  }
}

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  MyApp({Key key}) : super(key: key);

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

class _MyAppState extends State<MyApp> {
Future<Album> futureAlbum;

  @override
  void initState() {
    super.initState();
    futureAlbum = fetchAlbum();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Fetch Data Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('Fetch Data Example'),
        ),
        body: Center(
          child: FutureBuilder<Album>(
            future: futureAlbum,
            builder: (context, snapshot) {
              if (snapshot.hasData) {
                return Text(snapshot.data.title);
              } else if (snapshot.hasError) {
                return Text("${snapshot.error}");
              }

              // By default, show a loading spinner.
              return CircularProgressIndicator();
            },
          ),
        ),
      ),
    );
  }
}

谢谢

Answer 1

您可以使用connectivity library来监听wifi状态

@import '{ .btn as .my-button } from /bootstrap/_buttons.scss';
@import '[variables] from /bootstrap/_variables.scss';
@import '[mixins] from /bootstrap/mixins/_buttons.scss';

.my-button {
  @include button-variant($btn-primary-color, $btn-primary-bg, $btn-primary-border);
}

Answer 2

在发出任何HTTP请求之前，请使用连接性库检查网络状态。

没有互联网时颤振崩溃

2 个答案: