Flutter更新后Android Release构建报错：缺失android.window.BackEvent类

Flutter更新完成后，Debug模式下构建和运行均正常，但执行Release构建时出现如下错误：

ERROR: Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in /Users/chiragjuneja/Documents/work/playground/yashutales/badminton_score_tracker/build/flutter_inappwebview_android/outputs/mapping/release/missing_rules.txt.
ERROR: R8: Missing class android.window.BackEvent (referenced from: void io.flutter.embedding.android.FlutterActivity.startBackGesture(android.window.BackEvent) and 3 other contexts)

解决方案 #

经过测试验证，以下步骤可解决该问题：

• 新建proguard-rules.pro文件，添加ProGuard规则：

  -keep class android.window.BackEvent { *; }
  

• 修改Gradle文件中的buildTypes配置，让Release构建加载上述规则文件：

  buildTypes {
          release { 
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  

• 降级com.android.application插件版本，从8.1.0调整为7.3.0：
  原配置：

  plugins {
      id "dev.flutter.flutter-plugin-loader" version "1.0.0"
      id "com.android.application" version "8.1.0" apply false
      id "org.jetbrains.kotlin.android" version "1.8.22" apply false
  }
  

  修改后：

  plugins {
      id "dev.flutter.flutter-plugin-loader" version "1.0.0"
      id "com.android.application" version "7.3.0" apply false
      id "org.jetbrains.kotlin.android" version "1.8.22" apply false
  }
  

内容的提问来源于stack exchange，提问作者learning-everyday