in_app_purchase purchaseUpdatedStream侦听事件未触发

Question

我想在我的应用程序初始化后订阅purchaseUpdatedStream事件，因为如果购买失败，我想访问本地化文本以向用户显示消息。但是，我无法触发listen事件，除非在构建MaterialApp小部件之前订阅它。

工作示例：

class AppConfig extends InheritedWidget {
  AppConfig({
    @required this.appName,
    @required Widget child,
    @required this.prefs,
    @required this.devMode
  }) : super(child: child);

  final String appName;
  final SharedPreferences prefs;
  final bool devMode;

  static AppConfig of(BuildContext context) {
    return context.dependOnInheritedWidgetOfExactType();
  }

  @override
  bool updateShouldNotify(InheritedWidget oldWidget) => false;
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  var configuredApp = new AppConfig(
    appName: 'app',
    child: new MyApp(),
    prefs: await SharedPreferences.getInstance(),
    devMode: true,
  );

  InAppPurchaseConnection.enablePendingPurchases();
  runApp(configuredApp);
}

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

class _MyAppState extends State<MyApp> {

  StreamSubscription<List<PurchaseDetails>> _subscription;

  @override
  void initState() {
    Stream purchaseUpdated =
        InAppPurchaseConnection.instance.purchaseUpdatedStream;
    _subscription = purchaseUpdated.listen((purchaseDetailsList) {
      _listenToPurchaseUpdated(purchaseDetailsList, context);
    }, onDone: () {
      _subscription.cancel();
    }, onError: (error) {
      // handle error here.
    });
    super.initState();
  }

  @override
  void dispose() {
    _subscription.cancel();
    super.dispose();
  }

  void _listenToPurchaseUpdated(List<PurchaseDetails> purchaseDetailsList, BuildContext context) {
    var config = AppConfig.of(context);
    purchaseDetailsList.forEach((PurchaseDetails purchaseDetails) async {
      if (purchaseDetails.status == PurchaseStatus.pending) {
        print('pending');
      } else {
        if (purchaseDetails.status == PurchaseStatus.error) {
          print('error');
        } else if (purchaseDetails.status == PurchaseStatus.purchased) {
          print('purchased');
        }
        if (purchaseDetails.pendingCompletePurchase) {
          print('complete');
          await InAppPurchaseConnection.instance
              .completePurchase(purchaseDetails);
        }
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    var config = AppConfig.of(context);

    SystemChrome.setPreferredOrientations([
      DeviceOrientation.portraitUp,
      DeviceOrientation.portraitDown,
    ]);

    return MultiProvider(
      providers: [
      ],
      child: MaterialApp(
        debugShowCheckedModeBanner: false,
        title: config.appName,
        home: Scaffold(
          body: SomeWidget(); // whack a button in this widget that triggers a product purchase
        ),
      )
    );
  }
}

非工作示例：

class AppConfig extends InheritedWidget {
  AppConfig({
    @required this.appName,
    @required Widget child,
    @required this.prefs,
    @required this.devMode
  }) : super(child: child);

  final String appName;
  final SharedPreferences prefs;
  final bool devMode;

  static AppConfig of(BuildContext context) {
    return context.dependOnInheritedWidgetOfExactType();
  }

  @override
  bool updateShouldNotify(InheritedWidget oldWidget) => false;
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  var configuredApp = new AppConfig(
    appName: 'app',
    child: new AppScaffold(),
    prefs: await SharedPreferences.getInstance(),
    devMode: true,
  );

  InAppPurchaseConnection.enablePendingPurchases();
  runApp(configuredApp);
}

class AppScaffold extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    var config = AppConfig.of(context);

    SystemChrome.setPreferredOrientations([
      DeviceOrientation.portraitUp,
      DeviceOrientation.portraitDown,
    ]);

    return MultiProvider(
      providers: [
      ],
      child: MaterialApp(
        debugShowCheckedModeBanner: false,
        title: config.appName,
        home: Scaffold(
          body: MyApp()
        ),
      )
    );
  }
}

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

class _MyAppState extends State<MyApp> {

  StreamSubscription<List<PurchaseDetails>> _subscription;

  @override
  void initState() {
    Stream purchaseUpdated =
        InAppPurchaseConnection.instance.purchaseUpdatedStream;
    _subscription = purchaseUpdated.listen((purchaseDetailsList) {
      _listenToPurchaseUpdated(purchaseDetailsList, context);
    }, onDone: () {
      _subscription.cancel();
    }, onError: (error) {
      // handle error here.
    });
    super.initState();
  }

  @override
  void dispose() {
    _subscription.cancel();
    super.dispose();
  }

  void _listenToPurchaseUpdated(List<PurchaseDetails> purchaseDetailsList, BuildContext context) {
    var config = AppConfig.of(context);
    purchaseDetailsList.forEach((PurchaseDetails purchaseDetails) async {
      if (purchaseDetails.status == PurchaseStatus.pending) {
        print('pending');
      } else {
        if (purchaseDetails.status == PurchaseStatus.error) {
          print('error');
        } else if (purchaseDetails.status == PurchaseStatus.purchased) {
          print('purchased');
        }
        if (purchaseDetails.pendingCompletePurchase) {
          print('complete');
          await InAppPurchaseConnection.instance
              .completePurchase(purchaseDetails);
        }
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return SomeWidget(); // whack a button in this widget that triggers a product purchase
  }
}

有没有人能看看我是不是走错了路，或者解释一下为什么这个方法不起作用？

Answer 1

我自己的错误-我在应用程序中的其他地方使用了Navigator.pushReplacement(...);，这将触发子小部件上的dispose方法。很明显，现在我在想这件事。