dart 错误：不支持的操作：Flutter Web

xtfmy6hx 于 2023-04-27 发布在 Flutter

关注(0)|答案(2)|浏览(243)

我在我的flutter web应用程序中获取互联网状态，通过在我的服务中实现以下代码：

```import 'dart:async';
import 'dart:io';

import 'package:connectivity_plus/connectivity_plus.dart';
import 'package:rxdart/rxdart.dart';

enum ConnectionStatus {
  online,
  offline,
}

class CheckInternetConnection {
  final Connectivity _connectivity = Connectivity();

  /// We assume the initial status is Online
  final _controller = BehaviorSubject.seeded(ConnectionStatus.online);
  StreamSubscription? _connectionSubscription;

  CheckInternetConnection() {
    _checkInternetConnection();
  }

  Stream<ConnectionStatus> internetStatus() {
    _connectionSubscription ??= _connectivity.onConnectivityChanged
        .listen((_) => _checkInternetConnection());
    return _controller.stream;
  }

  Future<void> _checkInternetConnection() async {
    try {
      // Sometimes the callback is called when we reconnect to wifi,
      // but the internet is not really functional
      // This delay try to wait until we are really connected to internet
      final result = await InternetAddress.lookup('www.google.com');
      if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
        _controller.sink.add(ConnectionStatus.online);
      } else {
        _controller.sink.add(ConnectionStatus.offline);
      }
    } on SocketException catch (_) {
      _controller.sink.add(ConnectionStatus.offline);
    }
  }

  Future<void> close() async {
    await _connectionSubscription?.cancel();
    await _controller.close();
  }
}

但我得到以下错误：

'''Error: Unsupported operation: InternetAddress.lookup
    at Object.throw_ [as throw] (http://localhost:50773/dart_sdk.js:5080:11)
    at InternetAddress.lookup (http://localhost:50773/dart_sdk.js:59860:17)
at internet_conection_service.CheckInternetConnection.new._checkInternetConnection (http://localhost:50773/packages/flutter_web/src/core/services/internet_conection_service.dart.lib.js:86:50)
    at _checkInternetConnection.next (<anonymous>)
    at runBody (http://localhost:50773/dart_sdk.js:40660:34)
    at Object._async [as async] (http://localhost:50773/dart_sdk.js:40691:7)
at [_checkInternetConnection] (http://localhost:50773/packages/flutter_web/src/core/services/internet_conection_service.dart.lib.js:84:20)'''```

我已经尝试将dart：io更改为universal：io，但出现以下错误：

'''Error: UnimplementedError
    at Object.throw_ [as throw] (http://localhost:50773/dart_sdk.js:5080:11)
at InternetAddress.lookup (http://localhost:50773/packages/universal_io/src/io/sync_socket.dart.lib.js:3038:24)
at internet_conection_service.CheckInternetConnection.new._checkInternetConnection (http://localhost:50773/packages/flutter_web/src/core/services/internet_conection_service.dart.lib.js:87:64)
    at _checkInternetConnection.next (<anonymous>)
    at runBody (http://localhost:50773/dart_sdk.js:40660:34)'''

你能帮我一些选项，以便能够解决它在扑网，因为在移动的我没有问题.谢谢.

dart

来源：https://stackoverflow.com/questions/72791951/error-unsupported-operation-internetaddress-lookup-flutter-web

2条答案

按热度按时间

z8dt9xmd1#

我也面临这个问题，因为我正在使用以下方法来检查互联网连接：

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

然后我把这个方法改为：

Future<bool> hasNetwork() async {
  try {
    final result = await http.get(Uri.parse('www.google.com'));
    if(result.statusCode==200){
      return true;
    }
  else{
      return false;
  }
  }
   on SocketException catch (_) {
    return false;
  }
}

它解决了我的问题。

赞(0）回复(0）举报 2023-04-27

ilmyapht2#

虽然公认的答案是好的，但我认为这是一个更好的方法：当应用程序在浏览器上运行时，仅使用接受的答案。默认情况下，使用常规查找，这样更快。
顺便说一句，knownUrl可能是你的项目网站，如果你有一个。你必须确定是否为你启用了CORS。如果你不确定，只是尝试google.com，example.com和URL类似。

Future<bool> hasNetwork(String knownUrl) async {
  if (kIsWeb) {
    return _hasNetworkWeb(knownUrl);
  } else {
    return _hasNetworkMobile(knownUrl);
  }
}

Future<bool> _hasNetworkWeb(String knownUrl) async {
  try {
    final result = await http.get(Uri.parse(knownUrl));
    if (result.statusCode==200) return true;
  } on SocketException catch (_) {}
  return false;
}

Future<bool> _hasNetworkMobile(String knownUrl) async {
  try {
    final result = await InternetAddress.lookup(knownUrl);
    return result.isNotEmpty && result[0].rawAddress.isNotEmpty;
  } on SocketException catch (_) {}
  return false;
}

赞(0）回复(0）举报 2023-04-27

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dart 错误：不支持的操作：Flutter Web

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