错误：不支持的操作：InternetAddress.lookup Flutter Web

Question

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

```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();
  }
}

但我收到以下错误：

'''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)'''

你能帮我提供一些选项，以便能够在 flutter web 中解决它，因为在移动设备中我没有问题。谢谢。

Answer 1

我也遇到了这个问题，因为我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成了：

 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。