通过 Android APK 部署时，AWS Amplify Flutter 的身份验证注册功能不起作用

Question

我在我的 Flutter 应用程序中使用 AWS 的 Amplify Auth 的注册功能。当我在 Android Studio 中运行代码并在模拟器/手机上测试时，该功能运行良好。我可以向 Cognito 添加新用户并验证该用户。

但是，当我构建 APK 并尝试在同一个模拟器/手机上运行该 APK 时，注册功能在 logcat 中引发了一些错误，并且注册在调试期间无法正常工作。我不明白为什么当我通过 Android Studio 测试我的代码时不会发生这个错误。

这是错误：

2020-10-28 07:05:27.554 14035-14035/? E/MethodChannel#com.amazonaws.amplify/auth_cognito: Failed to handle method call
    e.d: null cannot be cast to non-null type java.lang.reflect.Method
        at com.amazonaws.amplify.amplify_auth_cognito.types.FlutterSignUpRequest.a(Unknown Source:203)
        at com.amazonaws.amplify.amplify_auth_cognito.types.FlutterSignUpRequest.<init>(Unknown Source:96)
        at com.amazonaws.amplify.amplify_auth_cognito.AuthCognito.i(Unknown Source:10)
        at com.amazonaws.amplify.amplify_auth_cognito.AuthCognito.a(Unknown Source:150)
        at d.a.b.a.j$a.a(Unknown Source:17)
        at io.flutter.embedding.engine.e.b.a(Unknown Source:57)
        at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(Unknown Source:4)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:336)
        at android.os.Looper.loop(Looper.java:174)
        at android.app.ActivityThread.main(ActivityThread.java:7397)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:935)
2020-10-28 07:05:27.556 14035-14063/? E/flutter: [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: NoSuchMethodError: The method 'forEach' was called on null.
    Receiver: null
    Tried calling: forEach(Closure: (dynamic, dynamic) => Set<Set<dynamic>>)
    #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51)
    #1      AmplifyAuthCognitoMethodChannel._throwError (package:amplify_auth_cognito/method_channel_auth_cognito.dart:330)
    #2      AmplifyAuthCognitoMethodChannel.signUp (package:amplify_auth_cognito/method_channel_auth_cognito.dart:40)
    <asynchronous suspension>
    #3      AmplifyAuthCognito.signUp (package:amplify_auth_cognito/amplify_auth_cognito.dart:45)
    <asynchronous suspension>
    #4      _State._registerUser (package:confab_app/SignUp_Screen.dart:36)
    <asynchronous suspension>

这是我的代码：

2020-10-28 07:05:27.554 14035-14035/? E/MethodChannel#com.amazonaws.amplify/auth_cognito: Failed to handle method call
    e.d: null cannot be cast to non-null type java.lang.reflect.Method
        at com.amazonaws.amplify.amplify_auth_cognito.types.FlutterSignUpRequest.a(Unknown Source:203)
        at com.amazonaws.amplify.amplify_auth_cognito.types.FlutterSignUpRequest.<init>(Unknown Source:96)
        at com.amazonaws.amplify.amplify_auth_cognito.AuthCognito.i(Unknown Source:10)
        at com.amazonaws.amplify.amplify_auth_cognito.AuthCognito.a(Unknown Source:150)
        at d.a.b.a.j$a.a(Unknown Source:17)
        at io.flutter.embedding.engine.e.b.a(Unknown Source:57)
        at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(Unknown Source:4)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:336)
        at android.os.Looper.loop(Looper.java:174)
        at android.app.ActivityThread.main(ActivityThread.java:7397)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:935)
2020-10-28 07:05:27.556 14035-14063/? E/flutter: [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: NoSuchMethodError: The method 'forEach' was called on null.
    Receiver: null
    Tried calling: forEach(Closure: (dynamic, dynamic) => Set<Set<dynamic>>)
    #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51)
    #1      AmplifyAuthCognitoMethodChannel._throwError (package:amplify_auth_cognito/method_channel_auth_cognito.dart:330)
    #2      AmplifyAuthCognitoMethodChannel.signUp (package:amplify_auth_cognito/method_channel_auth_cognito.dart:40)
    <asynchronous suspension>
    #3      AmplifyAuthCognito.signUp (package:amplify_auth_cognito/amplify_auth_cognito.dart:45)
    <asynchronous suspension>
    #4      _State._registerUser (package:confab_app/SignUp_Screen.dart:36)
    <asynchronous suspension>

Answer 1

问题在于R8删除一些amplify 的文件。proguard_rules.pro在文件中包含以下两项检查

-keep class com.amazonaws.** { *; }
-keep class com.amplifyframework.** { *; }

请注意：此错误仅出现在没有no-shrink标志的发布 apk 版本中。