Question

我已经配置并测试了所有从后端收取随机数的东西，但是我的Flutter android应用程序遇到了问题。

这是我的代码：

square_payment.dart

import 'package:flutter/material.dart';
import 'package:square_in_app_payments/models.dart';
import 'package:square_in_app_payments/in_app_payments.dart';

class SquarePayment extends StatefulWidget {
  @override
  _SquarePaymentState createState() => _SquarePaymentState();
}

class _SquarePaymentState extends State<SquarePayment> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.brown[900],
      body: Center(
        child: FlatButton(
          onPressed: () {
            _pay();
          },
          color: Colors.brown,
          child: Text("Pay now"),
        ),
      ),
    );
  }

  @override
  void initState() {
    super.initState();
    InAppPayments.setSquareApplicationId(
        'my_sandbox_application_id');
  }

  _pay() async {
    await InAppPayments.startCardEntryFlow(
        onCardNonceRequestSuccess: _success, onCardEntryCancel: _cancel);
  }

  _success(CardDetails result) {
    print(result.nonce);

    try {
      InAppPayments.completeCardEntry(onCardEntryComplete: () {print("success");});
    } on Exception catch (ex) {
      print(ex.toString());
    }
  }

  _cancel() {
    print("canceled");
  }
}

在显示Square的信用卡条目UI后，我按照here所述添加了一个沙盒测试信用卡值。它接受测试卡，并且现时已打印在控制台上，但随后我的应用程序崩溃并显示以下错误：

E/AndroidRuntime( 4007): FATAL EXCEPTION: main
E/AndroidRuntime( 4007): Process: discoverayush.squaretestapp, PID: 4007
E/AndroidRuntime( 4007): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=51789, result=-1, data=Intent { (has extras) }} to activity {discoverayush.squaretestapp/discoverayush.squaretestapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.view.ContextThemeWrapper.getResources()' on a null object reference
E/AndroidRuntime( 4007):    at android.app.ActivityThread.deliverResults(ActivityThread.java:4349)
E/AndroidRuntime( 4007):    at android.app.ActivityThread.handleSendResult(ActivityThread.java:4392)
E/AndroidRuntime( 4007):    at android.app.ActivityThread.-wrap22(ActivityThread.java)
E/AndroidRuntime( 4007):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1635)
E/AndroidRuntime( 4007):    at android.os.Handler.dispatchMessage(Handler.java:105)
E/AndroidRuntime( 4007):    at android.os.Looper.loop(Looper.java:156)
E/AndroidRuntime( 4007):    at android.app.ActivityThread.main(ActivityThread.java:6617)
E/AndroidRuntime( 4007):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime( 4007):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:942)
E/AndroidRuntime( 4007):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:832)
E/AndroidRuntime( 4007): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.view.ContextThemeWrapper.getResources()' on a null object reference
E/AndroidRuntime( 4007):    at sqip.flutter.internal.CardEntryModule.readCardEntryCloseExitAnimationDurationMs(CardEntryModule.java:215)
E/AndroidRuntime( 4007):    at sqip.flutter.internal.CardEntryModule.access$500(CardEntryModule.java:52)
E/AndroidRuntime( 4007):    at sqip.flutter.internal.CardEntryModule$1$1.onResult(CardEntryModule.java:86)
E/AndroidRuntime( 4007):    at sqip.flutter.internal.CardEntryModule$1$1.onResult(CardEntryModule.java:73)
E/AndroidRuntime( 4007):    at sqip.internal.CardEntryActivity$Companion.onActivityResult(CardEntryActivity.kt:596)
E/AndroidRuntime( 4007):    at sqip.CardEntry.handleActivityResult(CardEntry.kt:58)
E/AndroidRuntime( 4007):    at sqip.flutter.internal.CardEntryModule$1.onActivityResult(CardEntryModule.java:73)
E/AndroidRuntime( 4007):    at io.flutter.embedding.engine.FlutterEnginePluginRegistry$FlutterEngineActivityPluginBinding.onActivityResult(FlutterEnginePluginRegistry.java:634)
E/AndroidRuntime( 4007):    at io.flutter.embedding.engine.FlutterEnginePluginRegistry.onActivityResult(FlutterEnginePluginRegistry.java:367)
E/AndroidRuntime( 4007):    at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onActivityResult(FlutterActivityAndFragmentDelegate.java:546)
E/AndroidRuntime( 4007):    at io.flutter.embedding.android.FlutterActivity.onActivityResult(FlutterActivity.java:594)
E/AndroidRuntime( 4007):    at android.app.Activity.dispatchActivityResult(Activity.java:7188)
E/AndroidRuntime( 4007):    at android.app.ActivityThread.deliverResults(ActivityThread.java:4345)
E/AndroidRuntime( 4007):    ... 9 more
I/Process ( 4007): Sending signal. PID: 4007 SIG: 9
Lost connection to device.

android / app / build.gradle

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new FileNotFoundException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion 29

    lintOptions {
        disable 'InvalidPackage'
    }

    defaultConfig {
        applicationId "discoverayush.squaretestapp"
        minSdkVersion 24
        targetSdkVersion 29
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
        multiDexEnabled true
    }

    buildTypes {
        release {
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test:runner:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
    implementation 'com.google.firebase:firebase-analytics:17.2.2'
}

configurations.all {
        resolutionStrategy.eachDependency {details ->
            def requested = details.requested
            if (requested.group == "androidx.appcompat") {
                if (!requested.name.startsWith("multidex")) {
                    details.useVersion "1.+"
                }
            }
        }
    }

谢谢！

Answer 1

找到了解决方案。

问题出在Flutter SDK版本上。我使用的是 v1.12.13 + hotfix.8 ，但是square_in_app_payments尚不适用于此版本。卡输入完成后崩溃。因此，我将SDK降级为 v1.9.1 + hotfix.6 。

现在工作正常！

square_in_app_payments（颤振）-生成随机数后发生错误

1 个答案: