错误:Unsupported operation: InternetAddress.查找颤振网 &g

Question

我在我的flutter web应用程序中获得互联网状态，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，但我得到了以下错误:

'''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动网页，因为在移动我没有问题。谢谢你。

Answer 1

我也面临这个问题，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。

Answer 2

虽然接受的答案是有效的，而且很好，但我认为这是一个更好的方法:只在应用程序在浏览器上运行时使用接受的答案。默认情况下，使用更快的常规查找。

顺便说一下，knownUrl可以是你的项目网站，如果你有一个。您必须确保CORS为您启用。如果您不确定，请尝试google.com,example.com和url。

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;
}