我几乎读了所有的帖子，@dennmat的帖子对我最有用。虽然它对我没用，而且也过时了。我有更新颤振更新连接包(I。E connectivity_plus)和data_connection_checker(检查移动和wifi是否有实际的互联网连接)。 在这篇文章之后，你将能够连续监听互联网连接。

1. 添加依赖关系 A)连通性:^1.0.6 B) data_connection_checker: ^0.3.4

2. 处理所有连接的自定义类。

import 'dart:async';
import 'package:connectivity_plus/connectivity_plus.dart';
import 'package:data_connection_checker/data_connection_checker.dart'; 

class ConnectionUtil {
  //This creates the single instance by calling the `_internal` constructor specified below
  static final ConnectionUtil _singleton = new ConnectionUtil._internal();
  ConnectionUtil._internal();
  //This is what's used to retrieve the instance through the app
  static ConnectionUtil getInstance() => _singleton;
  //This tracks the current connection status
  bool hasConnection = false;
  //This is how we'll allow subscribing to connection changes
  StreamController connectionChangeController = StreamController();
  //flutter_connectivity
  final Connectivity _connectivity = Connectivity();
  void initialize() {
    _connectivity.onConnectivityChanged.listen(_connectionChange);
  }
  //flutter_connectivity's listener
  void _connectionChange(ConnectivityResult result) {
    hasInternetInternetConnection();
  }
  Stream get connectionChange => connectionChangeController.stream;
  Future<bool> hasInternetInternetConnection() async {
    bool previousConnection = hasConnection;
    var connectivityResult = await (Connectivity().checkConnectivity());
    //Check if device is just connect with mobile network or wifi
    if (connectivityResult == ConnectivityResult.mobile ||
        connectivityResult == ConnectivityResult.wifi) {
      //Check there is actual internet connection with a mobile network or wifi
      if (await DataConnectionChecker().hasConnection) {
        // Network data detected & internet connection confirmed.
        hasConnection = true;
      } else {
        // Network data detected but no internet connection found.
        hasConnection = false;
      }
    }
    // device has no mobile network and wifi connection at all
    else {
      hasConnection = false;
    }
    // The connection status changed send out an update to all listeners
    if (previousConnection != hasConnection) {
      connectionChangeController.add(hasConnection);
    }
    return hasConnection;
  }
}

检查任何地方的连接并倾听变化。

@override
  initState() {
    print('called');
    //Create instance
    ConnectionUtil connectionStatus = ConnectionUtil.getInstance();
    //Initialize
    connectionStatus.initialize();
    //Listen for connection change
    _connectionChangeStream = connectionStatus.connectionChange.listen((event) {
      print(event);
    });

    super.initState();
  }

切换飞行模式时检查日志。你应该得到有true和false值的日志。

注意:这将无法在flutter web工作，如果你想让它工作，请使用dio或http插件而不是data_connection_checker。

项目示例可以在这里找到。谢谢

Null安全代码:

One time check: Create this method: Future<bool> hasNetwork() async { try { final result = await InternetAddress.lookup('example.com'); return result.isNotEmpty && result[0].rawAddress.isNotEmpty; } on SocketException catch (_) { return false; } } Usage: bool isOnline = await hasNetwork(); Setting up a listener: Add the following dependency to your pubspec.yaml file. connectivity_plus: ^2.0.2 Full code: void main() => runApp(MaterialApp(home: HomePage())); class HomePage extends StatefulWidget { @override _HomePageState createState() => _HomePageState(); } class _HomePageState extends State<HomePage> { Map _source = {ConnectivityResult.none: false}; final MyConnectivity _connectivity = MyConnectivity.instance; @override void initState() { super.initState(); _connectivity.initialise(); _connectivity.myStream.listen((source) { setState(() => _source = source); }); } @override Widget build(BuildContext context) { String string; switch (_source.keys.toList()[0]) { case ConnectivityResult.mobile: string = 'Mobile: Online'; break; case ConnectivityResult.wifi: string = 'WiFi: Online'; break; case ConnectivityResult.none: default: string = 'Offline'; } return Scaffold( body: Center(child: Text(string)), ); } @override void dispose() { _connectivity.disposeStream(); super.dispose(); } } class MyConnectivity { MyConnectivity._(); static final _instance = MyConnectivity._(); static MyConnectivity get instance => _instance; final _connectivity = Connectivity(); final _controller = StreamController.broadcast(); Stream get myStream => _controller.stream; void initialise() async { ConnectivityResult result = await _connectivity.checkConnectivity(); _checkStatus(result); _connectivity.onConnectivityChanged.listen((result) { _checkStatus(result); }); } void _checkStatus(ConnectivityResult result) async { bool isOnline = false; try { final result = await InternetAddress.lookup('example.com'); isOnline = result.isNotEmpty && result[0].rawAddress.isNotEmpty; } on SocketException catch (_) { isOnline = false; } _controller.sink.add({result: isOnline}); } void disposeStream() => _controller.close(); }

截图:

来源:connectivity_plus和Günter Zöchbauer

使用connectivity_widget: ^0.1.7

添加附件:

dependencies:
     connectivity_widget: ^0.1.7

添加代码:

           ConnectivityWidget(
            builder: (context, isOnline) => Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Text(
                    "${isOnline ? 'Connected' : 'Offline'}",
                    style: TextStyle(
                        fontSize: 30,
                        color: isOnline ? Colors.green : Colors.red),
                  ),
                ],
              ),
            ),
          )

输出:

我有一些问题与接受的答案，但似乎它解决了别人的答案。我想要一个解决方案，可以从它使用的url得到响应，所以我认为http将是伟大的功能，为此，我发现这个答案真的很有帮助。如何使用HTTP请求(Flutter/Dart)检查Internet连接?

连接插件在其文档中声明，它只在有网络连接的情况下提供信息，但不包括网络连接到Internet的情况

请注意，在Android上，这并不保证连接到互联网。例如，应用程序可能有wifi接入，但它可能是一个VPN或酒店wifi，没有接入。

你可以使用

import 'dart:io';
...
try {
  final result = await InternetAddress.lookup('example.com');
  if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
    print('connected');
  }
} on SocketException catch (_) {
  print('not connected');
}

更新

不建议使用连接包。请使用官方的Flutter Community connectivity_plus包。

import 'dart:async';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:app_settings/app_settings.dart';
import 'package:connectivity/connectivity.dart';

class InternetConnect extends StatefulWidget {
  @override
  InternetConnectState createState() => InternetConnectState();
}

class InternetConnectState extends State<InternetConnect> {
  ConnectivityResult previous;
  bool dialogshown = false;
  StreamSubscription connectivitySubscription;

  Future<bool> checkinternet() async {
    try {
      final result = await InternetAddress.lookup('google.com');
      if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
        return Future.value(true);
      }
    } on SocketException catch (_) {
      return Future.value(false);
    }
  }

  void checkInternetConnect(BuildContext context) {
    connectivitySubscription = Connectivity()
        .onConnectivityChanged
        .listen((ConnectivityResult connresult) {
      if (connresult == ConnectivityResult.none) {
        dialogshown = true;
        showDialog(
            context: context, barrierDismissible: false, child: alertDialog());
      } else if (previous == ConnectivityResult.none) {
        checkinternet().then((result) {
          if (result == true) {
            if (dialogshown == true) {
              dialogshown = false;
              Navigator.pop(context);
            }
          }
        });
      }

      previous = connresult;
    });
  }

  AlertDialog alertDialog() {
    return AlertDialog(
      title: Text('ERROR'),
      content: Text("No Internet Detected."),
      actions: <Widget>[
        FlatButton(
          // method to exit application programitacally

          onPressed: () {
            AppSettings.openWIFISettings();
          },
          child: Text("Settings"),
        ),
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

    and you can use this method in init of any class

@override
void initState() {
  // TODO: implement initState
  InternetConnectState().checkInternetConnect(context);
  super.initState();
}