如何在 Flutter for Android 中使用 in_app_purchase 查看订阅状态？

问：

我想知道如何检查用户是否具有有效的订阅。在这种情况下，我创建了一个 1 个月的订阅，一切正常。但是，我可以通过什么方式确定用户的订阅是否仍处于活动状态？我正在使用 in_app_purchase 库，我注意到访问过去购买的方式已更新。在我的代码中，我将行 updating 修改为 .尽管进行了此修复，我仍然收到错误，因为未定义“PurchaserInfo”。另外，我不确定我是否以正确的方式实现了这一点，因为这是我第一次在 Flutter 中使用订阅。我提前感谢任何指导或帮助。谢谢！:)final PurchaserInfo purchaserInfo = await InAppPurchase.instance.queryPastPurchases();InAppPurchaseConnection.instanceInAppPurchase.instance

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:in_app_purchase/in_app_purchase.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:shared_preferences/shared_preferences.dart';




class SubscriptionStatusChecker extends StatefulWidget {
  @override
  _SubscriptionStatusCheckerState createState() =>
      _SubscriptionStatusCheckerState();
}

class _SubscriptionStatusCheckerState extends State<SubscriptionStatusChecker> {
  bool _isSubscriptionActive = false;

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

  Future<void> _checkSubscriptionStatus() async {
    try {
      final PurchaserInfo purchaserInfo = await InAppPurchase.instance
          .queryPastPurchases(); 

      final List<PurchaseDetails> purchases =
          purchaserInfo.purchases.toList();

      for (var purchase in purchases) {
        if (purchase.productID == 's2424' &&
            purchase.status == PurchaseStatus.purchased) {
          setState(() {
            _isSubscriptionActive = true;
          });
          break;
        }
      }
    } catch (e) {
      Fluttertoast.showToast(
        msg: 'Error: $e',
        gravity: ToastGravity.BOTTOM,
        timeInSecForIosWeb: 1,
        backgroundColor: Colors.red,
        textColor: Colors.white,
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Subscription Status Checker'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              'Estado de la suscripción:',
              style: TextStyle(fontSize: 18),
            ),
            Text(
              _isSubscriptionActive ? 'Activa' : 'Inactiva',
              style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold),
            ),
          ],
        ),
      ),
    );
  }
}




class UpdatePlan extends StatefulWidget {
  @override
  _UpdatePlanScreenState createState() => _UpdatePlanScreenState();
}

class _UpdatePlanScreenState extends State<UpdatePlan> {
  final InAppPurchase _inAppPurchase = InAppPurchase.instance;
  final FirebaseFirestore _firestore = FirebaseFirestore.instance;

  static const String _productId = 's2424'

  final StreamController<List<PurchaseDetails>> _purchaseUpdatedController =
      StreamController<List<PurchaseDetails>>.broadcast();

  Stream<List<PurchaseDetails>> get purchaseUpdatedStream =>
      _purchaseUpdatedController.stream;

  late StreamSubscription<List<PurchaseDetails>> _subscription;

  bool _isPlanPremiumActive = false;

  bool get isPlanPremiumActive => _isPlanPremiumActive;

  String? _username;

  @override
  void initState() {
    super.initState();
    _loadUsername();
    initialize();
  }

  void _loadUsername() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    setState(() {
      _username = prefs.getString('username');
    });
  }

  void initialize() async {
    final bool available = await _inAppPurchase.isAvailable();
    if (!available) {
      // The store is not available. Update the UI accordingly.
      return;
    }

    await _inAppPurchase.restorePurchases();

    _subscription = _inAppPurchase.purchaseStream.listen((purchaseDetailsList) {
      _handlePurchases(purchaseDetailsList);
    }, onDone: () {
      _subscription.cancel();
    }, onError: (error) {
      // Handle errors here.
    });
  }

  void _handlePurchases(List<PurchaseDetails> purchaseDetailsList) {
    for (var purchaseDetails in purchaseDetailsList) {
      if (purchaseDetails.status == PurchaseStatus.purchased) {
        if (purchaseDetails.productID == _productId) {
          _grantPlanPremium();
          _updateFirebaseSubscription(purchaseDetails);
        }
      } else if (purchaseDetails.status == PurchaseStatus.error) {
        Fluttertoast.showToast(
          msg: 'Error al realizar la compra: ${purchaseDetails.error}',
          gravity: ToastGravity.BOTTOM,
          timeInSecForIosWeb: 1,
          backgroundColor: Colors.red,
          textColor: Colors.white,
        );
      }
    }
    _purchaseUpdatedController.add(purchaseDetailsList);
  }

  void _grantPlanPremium() {
    setState(() {
      _isPlanPremiumActive = true;
    });
  }

  Future<void> purchaseProduct() async {
    try {
      final PurchaseParam purchaseParam =
          PurchaseParam(productDetails: await _getProductDetails());
      await _inAppPurchase.buyNonConsumable(purchaseParam: purchaseParam);
    } catch (error) {
      Fluttertoast.showToast(
        msg: 'Error al iniciar la compra: $error',
        gravity: ToastGravity.BOTTOM,
        timeInSecForIosWeb: 1,
        backgroundColor: Colors.red,
        textColor: Colors.white,
      );
    }
  }

  Future<ProductDetails> _getProductDetails() async {
    final Set<String> ids = <String>{_productId};
    final ProductDetailsResponse response =
        await _inAppPurchase.queryProductDetails(ids);
    return response.productDetails.first;
  }

 void _updateFirebaseSubscription(PurchaseDetails purchaseDetails) {
    if (_username != null) {
      
      _firestore.collection('users').doc(_username).update({
        'subscription': true,
      });
    }
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Test'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              'Premium Plan: ${_isPlanPremiumActive ? 'Active' : 'Inactive'}',
              style: TextStyle(fontSize: 18),
            ),
            ElevatedButton(
              onPressed: () => purchaseProduct(),
              child: Text('Update VIP'),
            ),
            ElevatedButton(
              onPressed: () => SubscriptionStatusChecker(),
              child: Text('Status'),
            ),
          ],
        ),
      ),
    );
  }
}

我看到了这个线程，但是，它没有响应： 如何使用in_app_purchase检查用户是否有活动订阅 我的期望是能够确定用户是否具有活动订阅。