Flutter发布的apk无法在PayHere中进行支付

Question

我的 flutter 应用程序无法在发布 apk 中的 PayHere 支付网关中继续付款。在调试模式下并在发布模式下运行应用程序工作正常。但只有在构建和运行release apk时才会出现错误。

Answer 1

根本原因

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该问题是由 Flutter\xe2\x80\x99s R8 代码收缩引起的，在发布版本中默认打开该代码收缩，如此处所述。从 Android Gradle 版本 3.4.0 开始，R8 不再使用 Proguard，如此处所述。然而，R8 仍然使用确切格式的混淆器规则文件，以排除仅在明确提供的情况下被混淆/删除的类。否则，未使用的代码将从最终产品中删除。

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据了解，Flutter 和 Dart 内部用于链接 PayHere Android SDK 和 PayHere Flutter Dart 组件的 MethodChannel 受到了此代码混淆过程的影响。

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解决方案

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有两种解决方案可以解决该问题。如果开发人员扩展现有的代码库，第一个可以提供更大的灵活性。第二种解决方案是快速 \xe2\x80\x9chotfix\xe2\x80\x9d，它禁用代码混淆以方便应用。

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注意：在执行下文提到的解决方案之前，请保留现有代码库的备份。即使您启用了版本控制，也建议执行此步骤，因为 .gitignore 定义可能不会跟踪携带敏感信息的文件的更改。

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1.使用Android Proguard规则的解决方案

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如果您愿意手动创建 Pro-guard 规则文件或者您已经配置了 Pro-guard 规则，则首选此解决方案。下面提到了所需的步骤。

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1. 在您喜欢的 IDE 中打开您的 Flutter 项目。

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2. 在 \xe2\x80\x9c/android/app\xe2\x80\x9d 文件夹中创建一个名为 \xe2\x80\x9cproguard-rules.pro\xe2\x80\x9d 的新文件。

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3. 在上面步骤 2 中创建的 \xe2\x80\x9cproguard-rules.pro\xe2\x80\x9d 文件中添加以下代码行。

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   #Flutter Wrapper\n-keep class io.flutter.app.** { *; } \n-keep class io.flutter.plugin.** { *; } \n-keep class io.flutter.util.** { *; } \n-keep class io.flutter.view.** { *; } \n-keep class io.flutter.** { *; }\n-keep class io.flutter.plugins.** { *; } \n\n#the required rule\n-keep class lk.payhere.** { *; }\n

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上面的代码排除了所有默认的 Flutter 库和 PayHere Android SDK 类。确保没有重叠的规则。如果您已有 \xe2\x80\x9cproguard-rules.pro\xe2\x80\x9d 文件，则只需添加最后一行。

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4. 打开位于 \xe2\x80\x9c/android/app\xe2\x80\x9d 文件夹中的 \xe2\x80\x9cbuild.gradle\xe2\x80\x9d 文件。
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5. Find the \xe2\x80\x9cbuildTypes\xe2\x80\x9d block inside the top-level \xe2\x80\x9candroid\xe2\x80\x9d block. Note that in the context of this issue, developers are building the Flutter App for release mode and should already have the \xe2\x80\x9cbuildTypes\xe2\x80\x9d block written.
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6. Instruct the Android Build system to keep code minification/obfuscation turned on, and to use your Proguard rules defined in Step 3 using the following highlighted code.
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Note that if you have already set up Proguard previously, you might be able to skip this step.

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android {\n  compileSdkVersion 29\n   sourceSets {\n     main.java.srcDirs += \'src/main/kotlin\'\n  }\n   lintOptions {\n     disable \'InvalidPackage\'\n  }\n   defaultConfig {\n     // Android configurations are usually here\n  }\n   // Signing Configurations are usually here\n   buildTypes {\n     release {\n       signingConfig signingConfigs.debug\n\n       // add these code lines\n       minifyEnabled true\n       useProguard true\n       proguardFiles getDefaultProguardFile(\'proguard-android.txt\'), \'proguard-rules.pro\'\n    } \n  }\n}\n

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7. Perform a Flutter clean task and build your Release APK. Your issue should be resolved now.
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2. Solution by disabling modification

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If you do not require code obfuscation or minification in your Release APK, you can simply disable this feature altogether for the Android code. The required steps are mentioned below.

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1. Open up your Flutter Project in your preferred IDE

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2. Open the \xe2\x80\x9cbuild.gradle\xe2\x80\x9d file in the \xe2\x80\x9c/android/app\xe2\x80\x9d folder.

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3. Find the \xe2\x80\x9candroid\xe2\x80\x9d block, within it locate the \xe2\x80\x9cbuildTypes\xe2\x80\x9d and \xe2\x80\x9crelease\xe2\x80\x9d blocks.

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4. Add the following mentioned code to disable code modification.

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   android {\n    compileSdkVersion 29\n    sourceSets {\n        main.java.srcDirs += \'src/main/kotlin\'\n    }\n\n    lintOptions {\n        disable \'InvalidPackage\'\n    }\n\n    defaultConfig {\n        // Android configurations are usually here\n    }\n    // Signing Configurations are usually here\n    buildTypes {\n        release {\n            signingConfig signingConfigs.debug\n\n            // add these code lines\n            minifyEnabled false\n            shrinkResources false\n        } \n    }\n}\n

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5. Perform a Flutter clean task and build your Release APK. Your issue should be resolved now.

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Happy coding :D

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