Question

此实现代码是一个简单的 Riverpod 提供程序，我们可以检测互联网连接：

enum NetworkStatus { NotDetermined, On, Off }

final networkAwareProvider = StateNotifierProvider((ref)=>NetworkDetectorNotifier());

class NetworkDetectorNotifier extends StateNotifier<NetworkStatus> {
  StreamController<ConnectivityResult> controller =
  StreamController<ConnectivityResult>();

  NetworkStatus lastResult = NetworkStatus.NotDetermined;

  NetworkDetectorNotifier() : super(NetworkStatus.NotDetermined) {

    Connectivity().onConnectivityChanged.listen((ConnectivityResult result) {
      NetworkStatus newState;
      switch (result) {
        case ConnectivityResult.mobile:
        case ConnectivityResult.wifi:
          newState = NetworkStatus.On;
          break;
        case ConnectivityResult.none:
          newState = NetworkStatus.Off;
          break;
      }

      if (newState != state) {
        state = newState;
      }
    });
  }
}

在这里我如何处理 controller 并且基本上当我们想在 ConsumerWidget 中使用它时，我们可以拥有：

class Screen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Consumer(builder: (context, watch, child) {
      var network = watch(networkAwareProvider).state;
      if (network == NetworkStatus.Off) {
        return Center(child: Text("No network"));
      }

      return Container(child: Text("Normal stuff"));
    });
  }
}

with Riverpod kook 如何在其中使用 whatch 方法？例如：

class Profile extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final _network = useProvider(networkAwareProvider);
    final connected = _network.watch(networkAwareProvider).state;
    if(connected){
      print ('connected');
    }else{
      print ('not connected');
    }
 }
}

我收到此错误：

Class 'NetworkStatus' has no instance method 'watch'.
Receiver: Instance of 'NetworkStatus'
Tried calling: watch(Instance of 'StateNotifierProvider<NetworkDetectorNotifier, dynamic>')

提前致谢

Answer 1

useProvider 的工作方式与 ref.watch 相同，因此您只需：

final status = useProvider(networkAwareProvider);
if (status == ...) {
  ...
}

Flutter Riverpod 配置 StreamController 并在 HookWidget 中使用

1 个答案: