Flutter应用内支付功能插件in_app_payment的使用

当然，以下是一个关于如何在Flutter应用中使用in_app_payment插件来实现应用内支付功能的代码示例。请注意，in_app_payment插件目前主要支持Google Play和App Store的支付功能，你需要根据具体的平台进行相应的配置。

首先，确保你的Flutter项目已经添加了in_app_payment插件。在你的pubspec.yaml文件中添加以下依赖：

dependencies:
  flutter:
    sdk: flutter
  in_app_purchase: ^x.y.z  # 请使用最新版本号

然后运行flutter pub get来安装依赖。

接下来，你需要配置Google Play和App Store的应用内购买项目。这包括设置产品ID、价格、描述等信息。具体步骤请参考Google Play和App Store的官方文档。

下面是一个简单的Flutter代码示例，展示了如何使用in_app_purchase插件来查询和购买应用内商品：

import 'package:flutter/material.dart';
import 'package:in_app_purchase/in_app_purchase.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: PurchaseScreen(),
    );
  }
}

class PurchaseScreen extends StatefulWidget {
  @override
  _PurchaseScreenState createState() => _PurchaseScreenState();
}

class _PurchaseScreenState extends State<PurchaseScreen> {
  late InAppPurchaseConnection _purchaseConnection;
  late List<ProductDetails> _products;
  late List<PurchaseDetails> _purchases;
  bool _loading = true;

  @override
  void initState() {
    super.initState();
    _purchaseConnection = InAppPurchaseConnection.instance;

    _setupPurchases();
  }

  Future<void> _setupPurchases() async {
    try {
      // 查询可用的产品
      ProductDetailsResponse productResponse = await _purchaseConnection.queryProductDetails([
        'your_product_id_1', // 替换为你的产品ID
        'your_product_id_2', // 替换为你的产品ID
      ]);

      if (productResponse.productDetails.isEmpty) {
        // 处理无法获取产品详情的情况
        return;
      }

      setState(() {
        _products = productResponse.productDetails;
        _purchases = [];
        _loading = false;
      });

      // 监听购买更新
      _purchaseConnection.purchaseUpdatedStream.listen((purchaseDetailsList) {
        setState(() {
          _purchases = purchaseDetailsList;
          // 处理购买完成后的逻辑，比如更新UI或解锁内容
          _consumePurchases(purchaseDetailsList);
        });
      }, onDone: () {
        _purchaseConnection.endConnection();
      });
    } catch (e) {
      // 处理错误
      print(e);
      setState(() {
        _loading = false;
      });
    }
  }

  Future<void> _consumePurchases(List<PurchaseDetails> purchases) async {
    for (PurchaseDetails purchase in purchases) {
      if (purchase.pendingCompletion == true) {
        try {
          await _purchaseConnection.completePurchase(purchase);
        } catch (e) {
          print("Failed to complete purchase: $e");
        }
      }
    }
  }

  Future<void> _buyProduct(ProductDetails product) async {
    try {
      PurchaseParam purchaseParam = PurchaseParam(
        productDetails: product,
        applicationUserName: 'user_id_123', // 替换为用户的唯一标识符
      );

      PurchaseResult result = await _purchaseConnection.buyNonConsumable(
        purchaseParam: purchaseParam,
      );

      if (result.responseCode == BillingResponseCode.ok) {
        // 处理购买成功的逻辑
        print("Purchase successful: ${result.purchaseDetails}");
      } else {
        // 处理购买失败的情况
        print("Purchase failed: ${result.debugMessage}");
      }
    } catch (e) {
      // 处理购买过程中的错误
      print("Error while purchasing: $e");
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('In-App Purchases'),
      ),
      body: _loading
          ? Center(child: CircularProgressIndicator())
          : ListView(
              children: <Widget>[
                for (ProductDetails product in _products)
                  Padding(
                    padding: const EdgeInsets.symmetric(vertical: 8.0),
                    child: ListTile(
                      title: Text(product.title),
                      subtitle: Text(product.price),
                      trailing: IconButton(
                        icon: Icon(Icons.shopping_cart),
                        onPressed: () => _buyProduct(product),
                      ),
                    ),
                  ),
                for (PurchaseDetails purchase in _purchases)
                  Padding(
                    padding: const EdgeInsets.symmetric(vertical: 8.0),
                    child: ListTile(
                      title: Text("Purchase successful: ${purchase.productID}"),
                    ),
                  ),
              ],
            ),
    );
  }
}

在这个示例中，我们做了以下几件事情：

1. 初始化InAppPurchaseConnection实例。
2. 查询应用内购买的产品详情。
3. 监听购买更新流，处理购买完成后的逻辑。
4. 提供一个按钮来购买产品，并在购买成功后显示购买成功的消息。

请根据你的具体需求调整代码，比如添加错误处理、用户身份验证等逻辑。此外，别忘了在Google Play和App Store上配置相应的产品ID和价格。