颤动：添加“image_cropper”和“contacts_service”包时构建错误

Question

我可以成功构建并运行一个全新的扑动项目。 但是，当我将image_cropper: ^1.0.0和contacts_service: ^0.2.4包添加到pubspec.yaml并运行flutter packages get ，我无法再构建项目，并得到此构建错误：

D8: Program type already present: android.support.v4.app.INotificationSideChannel

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.
> com.android.builder.dexing.DexArchiveMergerException: Error while merging dex archives: E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\2.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\3.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\4.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\5.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\6.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\7.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\8.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\9.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\10.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\11.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\12.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\13.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\14.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\15.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\16.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\17.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\18.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\19.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\20.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\21.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\22.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\23.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\24.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\25.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\26.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\27.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\28.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\29.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\30.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\31.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\32.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\33.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\34.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\35.jar, E:\Projects\flutter\hello\build\app\intermediates\transforms\dexBuilder\debug\36.jar
  Learn how to resolve the issue at https://developer.android.com/studio/build/dependencies#duplicate_classes.
  Program type already present: android.support.v4.app.INotificationSideChannel

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 1m 19s
*******************************************************************************************
The Gradle failure may have been because of AndroidX incompatibilities in this Flutter app.
See https:///CP92wY for more information on the problem and how to fix it.
*******************************************************************************************
Finished with error: Gradle task assembleDebug failed with exit code 1

我不太了解这个错误，但似乎这两个包之间存在命名冲突（因为错误文本中有duplicate_classes ）。 这有什么解决方法吗？

请注意，对于我来说任何其他包都不会发生此错误。

Answer 1

在build.gradle中，defaultConfig添加multiDexEnabled true

Answer 2

这是Android X兼容性问题。 我可以按照这里提到的步骤修复它，但总结如下：

1. 首先确保app / build.gradle中的compileSdkVersion至少为28。 此属性控制Gradle用于构建APK的Android SDK版本。 它不会影响您的应用可以运行的最低SDK版本。
2. 右键单击flutter项目的android目录并使用此菜单打开它： Flutter > Open android module in android studio
3. 在新打开的项目中，从菜单中选择Refactor > Migrate to AdnroidX
4. 关闭项目并再次打开flutter项目。