方法:

1. File > Project Structure (Command + ;) > Under Project Settings/Project > Set Project SDK to Android API 29 Platform(File>Project Structure（Command +;）>在项目设置/项目下>将Project SDK设置为Android API 29 Platform)

2. There should be a notification stating there is an invalid item in the dependencies list under Project Structure/Problems. If there is, go to Project Structure > Under Project Settings/Modules > select app_name_android > Dependencies tab > choose the latest "Android API 29 Platform" in the Module SDK box.(应该有一个通知，指出依赖项列表中“项目结构/问题”下的项目无效。如果存在，请转到“项目结构”>“项目设置/模块”下，选择“ app_name_android”>“依赖项”选项卡，然后在“模块SDK”框中选择最新的“ Android API 29平台”)

3.Update GradleException() to FileNotFoundException() under android/app/build_gradle since it‘s not supported in the Java version of Android API 29That‘s it! You should notice the Android API 29 Platform is now visible under External Libraries.(将GradleException（）更新为android / app / build_gradle下的FileNotFoundException（），因为Java版本的Java API不支持29而已！您应该注意到，Android API 29平台现在在“外部库”下可见。)

Flutter Project Android Studio build.gradle GradleException