Flutter集成UPI支付遇Kotlin版本报错，求解决方案

一、彻底检查Gradle配置的Kotlin版本 #

问题大概率出在多文件配置不一致，需逐一确认：

• 打开项目根目录的build.gradle（android文件夹外的那个），将ext.kotlin_version设置为稳定版1.8.x（避免用2.0.x预览版，部分第三方包不兼容）：

  buildscript {
      ext.kotlin_version = '1.8.20'
      repositories {
          google()
          mavenCentral()
      }
      dependencies {
          classpath "com.android.tools.build:gradle:7.4.2"
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
      }
  }
  

• 打开android/app/build.gradle，确认kotlin插件引用的是上述变量，无硬编码旧版本：

  apply plugin: 'kotlin-android'
  // 确保此处未单独写死版本号
  

• 检查gradle.properties文件，若存在kotlin.version类配置，同步为相同版本：

  kotlin.version=1.8.20
  

二、清理缓存与重新构建 #

1. 执行终端命令：

   flutter clean
   flutter pub get
   

2. 删除项目android/.gradle目录，或通过Android Studio的File > Invalidate Caches / Restart清理缓存
3. 重新运行项目

三、修复自定义包的配置 #

如果你复刻了upi_pay/flutter_upi包：

• 打开自定义包的android/build.gradle，确保其ext.kotlin_version与主项目一致，且无硬编码低于1.5.40的版本
• 确认包的pubspec.yaml未依赖其他强制旧Kotlin版本的包
• 本地引用自定义包时，确保路径正确：

  dependencies:
    flutter_upi:
      path: ./custom_flutter_upi
  

四、替代方案：绕过第三方包直接集成UPI #

若以上方法均无效，直接通过原生Intent调用UPI应用（无第三方包依赖，完全可控）：

1. Flutter端创建MethodChannel，调用Android原生代码：

   class _PaymentPageState extends State<PaymentPage> {
     static const platform = MethodChannel('upi_payment');
   
     Future<void> _startUpiTransfer() async {
       try {
         await platform.invokeMethod('initiateTransfer', {
           'upiId': 'recipient@upi',
           'name': '收款方名称',
           'amount': '50.00',
           'note': 'P2P转账'
         });
       } on PlatformException catch (e) {
         print('错误：${e.message}');
       }
     }
   
     @override
     void initState() {
       super.initState();
       platform.setMethodCallHandler((call) async {
         if (call.method == 'transferResult') {
           String response = call.arguments;
           // 解析UPI响应字符串，判断交易状态
           print('交易响应：$response');
         }
       });
     }
   
     @override
     Widget build(BuildContext context) {
       return Scaffold(
         body: Center(
           child: ElevatedButton(
             onPressed: _startUpiTransfer,
             child: const Text('发起UPI转账'),
           ),
         ),
       );
     }
   }
   

2. Android原生端构造UPI请求Intent：

   class MainActivity : FlutterActivity() {
       private val CHANNEL = "upi_payment"
       private val UPI_REQUEST_CODE = 101
   
       override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
           super.configureFlutterEngine(flutterEngine)
           MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler { call, result ->
               if (call.method == "initiateTransfer") {
                   val upiId = call.argument<String>("upiId")
                   val name = call.argument<String>("name")
                   val amount = call.argument<String>("amount")
                   val note = call.argument<String>("note")
                   launchUpiIntent(upiId, name, amount, note, result)
               } else {
                   result.notImplemented()
               }
           }
       }
   
       private fun launchUpiIntent(upiId: String?, name: String?, amount: String?, note: String?, result: MethodChannel.Result) {
           val uri = Uri.parse("upi://pay").buildUpon()
               .appendQueryParameter("pa", upiId)
               .appendQueryParameter("pn", name)
               .appendQueryParameter("am", amount)
               .appendQueryParameter("cu", "INR")
               .appendQueryParameter("tn", note)
               .build()
   
           val intent = Intent(Intent.ACTION_VIEW, uri)
           val chooser = Intent.createChooser(intent, "选择UPI应用")
           if (packageManager.resolveActivity(chooser, 0) != null) {
               startActivityForResult(chooser, UPI_REQUEST_CODE)
           } else {
               result.error("NO_UPI_APP", "未安装任何UPI应用", null)
           }
       }
   
       override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
           super.onActivityResult(requestCode, resultCode, data)
           if (requestCode == UPI_REQUEST_CODE) {
               val response = data?.getStringExtra("response")
               val channel = MethodChannel(flutterEngine?.dartExecutor?.binaryMessenger, CHANNEL)
               channel.invokeMethod("transferResult", response)
           }
       }
   }
   

内容的提问来源于stack exchange，提问作者Deepiga Dharshini