Flutter集成PhonePe Payment SDK调用init方法遇MissingPluginException

问题描述 #

在Flutter应用中集成PhonePe Payment SDK，调用PhonePePaymentSdk.init()方法时触发MissingPluginException异常。

代码片段 #

Flutter组件代码 #

import 'dart:convert';
import 'package:crypto/crypto.dart';
import 'package:flutter/material.dart';
import 'package:phonepe_payment_sdk/phonepe_payment_sdk.dart';

class PhonePePaymentScreen extends StatefulWidget {
  PhonePePaymentScreen();

  @override
  State<PhonePePaymentScreen> createState() => _PhonePePaymentScreenState();
}

class _PhonePePaymentScreenState extends State<PhonePePaymentScreen> {

  @override
  void initState() {
    initiatePayment();
    body = getCheckSum().toString();
    super.initState();
  }

  String environmentValue = "SANDBOX";
  String appId = "";
  String merchantId = "PGTESTPAYUAT";
  bool enableLogging = true;
  String saltKey = "099eb0cd-02cf-4e2a-8aca-3e6c6aff0399";
  String saltIndex = "1";
  String callback = "https://webhook.site/ba843c01-f6a6-4076-8fba-24b5719b3f66";
  String apiEndPoint = "/pg/v1/pay";

  Object result;
  String body = "";
  String checksum = "";

  void initiatePayment() async {
    PhonePePaymentSdk.init(environmentValue, appId, merchantId, enableLogging)
        .then((val) => {
      setState(() {
        result = 'PhonePe SDK Initialized - $val';
      })
    })
        .catchError((error) {
      handleError(error);
      return <dynamic>{};
    });
  }

  void handleError(error) {
    setState(() {
      result = error;
    });
  }

  void startTransactions() async {
    PhonePePaymentSdk.startTransaction(body, callback, checksum, "")
        .then((response) => {
      setState(() {
        if (response != null) {
          String status = response['status'].toString();
          String error = response['error'].toString();
          if (status == 'SUCCESS') {
            result = "Flow Completed - Status: Success!";
          } else {
            result =
            "Flow Completed - Status: $status and Error: $error";
          }
        } else {
          result = "Flow Incomplete";
        }
      })
    })

        .catchError((error) {
      handleError(error);
      return <dynamic>{};
    });
  }

  String getCheckSum() {
    final reqData = {
      "merchantId": merchantId,
      "merchantTransactionId": "MT7850590068188104",
      "merchantUserId": "MUID123",
      "amount": 1000,
      "callbackUrl": callback,
      "mobileNumber": "9999999999",
      "paymentInstrument": {"type": "PAY_PAGE"}
    };
    String encoded = base64.encode(utf8.encode(json.encode(reqData)));
    checksum = '${sha256.convert(utf8.encode(encoded+apiEndPoint+saltKey))}###$saltIndex';
    return encoded;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Payment Gateway"),
        backgroundColor: Color(0xFF009db5),
      ),
      body: Column(
        children: [
          Container(
            child: ElevatedButton(
              child: Text("Pay Now"),
              onPressed: () {
                startTransactions();
              },
            ),
          ),
          Text("$result"),
        ],
      ),
    );
  }
}

环境与配置信息 #

• Flutter版本：3.0.0
• Dart版本：2.17.0

pubspec.yaml配置 #

environment:
  sdk: ">=2.2.0 <3.0.0"

dependencies:
  crypto: ^3.0.2
  phonepe_payment_sdk: ^2.0.1

android/build.gradle配置 #

allprojects {
    repositories {
        google()
        jcenter()
        maven {
            url  "https://phonepe.mycloudrepo.io/public/repositories/phonepe-intentsdk-android"
        }
    }
}

解决方案 #

MissingPluginException通常是Flutter与原生平台插件通信未正确初始化导致的，按以下步骤排查修复：

1. 修正Dart SDK版本范围
   你的Flutter 3.0.0对应Dart 2.17.0，但pubspec里指定的SDK范围是>=2.2.0 <3.0.0，已经超出限制。修改pubspec.yaml的environment部分：

   environment:
     sdk: ">=2.17.0 <4.0.0"
   

   执行flutter pub get更新依赖。

2. 重新构建原生项目
   插件安装后需重新生成原生绑定文件，执行以下命令：

   flutter clean
   flutter pub get
   cd android && ./gradlew clean && cd ..
   flutter run
   

3. 验证Android端基础配置
   确认android/app/build.gradle中minSdkVersion不低于21（PhonePe SDK要求）：

   android {
       defaultConfig {
           minSdkVersion 21
           // 其他配置...
       }
   }
   

   若gradle同步失败，手动触发Android项目同步。

4. 检查init方法参数
   代码中appId为空字符串，部分SDK版本可能需要有效的沙箱appId，确认并填入PhonePe提供的对应参数。

5. 延迟调用init方法
   当前在initState中直接调用初始化方法，可能平台通道尚未就绪。改为延迟调用：

   @override
   void initState() {
     super.initState();
     Future.delayed(Duration(milliseconds: 500), () {
       initiatePayment();
     });
     body = getCheckSum().toString();
   }
   

完成以上步骤后重新运行应用，即可解决MissingPluginException问题。

内容的提问来源于stack exchange，提问作者Vicky