仅在有互联网连接时运行Flutter App [英] Run Flutter App only if internet connection is available

问题描述

我希望我的flutter应用程序仅在可以连接互联网的情况下运行。
如果没有互联网，请显示一个对话框（不存在互联网）
我正在使用连接插件，但仍然不满意。

I want my flutter app run only if internet connection is available. If the internet is not present show a dialog(internet is not present) I'm using conectivity plugin but still not satisfied.

此处是我的主要功能

Future main() async {
  try {
  final result = await InternetAddress.lookup('google.com');
  if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
    print('connected');
  }
} on SocketException catch (_) {
  print('not connected');
}
  runApp(MyApp());}

推荐答案

您不能直接在 main（）方法中使用对话框，因为没有有效的上下文可用。

You can't use dialog in main() method directly because there is no valid context available yet.

这是您要查找的基本代码。

Here is the basic code of what you are looking for.

void main() => runApp(MaterialApp(home: MyApp()));

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  void initState() {
    super.initState();
    Timer.run(() {
      try {
        InternetAddress.lookup('google.com').then((result) {
          if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
            print('connected');
          } else {
            _showDialog(); // show dialog
          }
        }).catchError((error) {
          _showDialog(); // show dialog
        });
      } on SocketException catch (_) {
        _showDialog();
        print('not connected'); // show dialog
      }
    });
  }

  void _showDialog() {
    // dialog implementation
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
            title: Text("Internet needed!"),
            content: Text("You may want to exit the app here"),
            actions: <Widget>[FlatButton(child: Text("EXIT"), onPressed: () {})],
          ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Internet")),
      body: Center(
        child: Text("Working ..."),
      ),
    );
  }
}

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