flutter - Flutter:是否可以在main.dart中一次实现一个 snackbar ，例如在连接状态更改时在所有屏幕上实现一次

Question

我对连接进行枚举:

enum ConnectivityStatus{
  Wifi,
  Cellular,
  Offline
}

然后创建服务以检查连接性:

import 'dart:async';

import 'package:Zabatnee/activities_app/enum/connectivity_status.dart';
import 'package:connectivity/connectivity.dart';

class ConnectivityService{

StreamController<ConnectivityStatus> connectionStatusController = StreamController<ConnectivityStatus>();

ConnectivityService(){
  Connectivity().onConnectivityChanged.listen((ConnectivityResult result) { 
    var connectionStatus = _getStatusFromResult(result);
    connectionStatusController.add(connectionStatus);
  });
}
  ConnectivityStatus _getStatusFromResult(ConnectivityResult result) {
    switch (result) {
      case ConnectivityResult.mobile:
        return ConnectivityStatus.Cellular;
      case ConnectivityResult.wifi:
        return ConnectivityStatus.Wifi;
      case ConnectivityResult.none:
        return ConnectivityStatus.Offline;
      default:
        return ConnectivityStatus.Offline;
    }
  }
}

，我需要在创建的所有屏幕中检查连接状态。我可以为所有屏幕一次做一次，还是必须逐一检查每个屏幕的连通性？

Answer 1

您可以一次检查连接状态，并将为您的所有应用实现。
您只需要创建一个包装器类并订阅Connectivity流并在该包装器类中应用逻辑即可。
您的整个小部件将被该小部件包装。

MaterialApp(
  ..
  home: ConnectivityWrapper(
    childWidget: YourWidget(), // replace this with your own home widget
  ),
);

包装窗口小部件将如下所示:

class ConnectivityWrapper extends StatefulWidget {
  
  ConnectivityWrapper(this.childWidget);
  
  final Widget childWidget;

  @override
  _ConnectivityWrapperState createState() => _ConnectivityWrapperState();
}

class _ConnectivityWrapperState extends State<ConnectivityWrapper> {

  StreamSubscription<ConnectivityStatus> subscription;

  @override
  void initState() {
    super.initState();

    subscription = connectionStatusController.stream.listen((status) 
      {
        if(status == ConnectivityStatus.Offline) {
          // Your logic here (Toast message or something else)
        }
      }, 
      onDone() {
        // Your logic here
      }, 
      onError: () {
        // Your logic here
      });
  }

  @override
  Widget build(BuildContext context) {
    return widget.childWidget;
  }

  @override
  void dispose() {
    // unsubscribe to the stream
    subscription.cancel();
    super.dispose();
  }
}