【发布时间】：2021-09-25 13:55:08
【问题描述】：
我目前正在构建一个 react-native 应用程序，每次运行时都会收到以下错误消息：react-native run-android
错误信息：
info Running jetifier to migrate libraries to AndroidX. You can disable it using "--no-jetifier" flag.
Jetifier found 1052 file(s) to forward-jetify. Using 8 workers...
info Starting JS server...
info Launching emulator...
error Failed to launch emulator. Reason: Emulator exited before boot..
warn Please launch an emulator manually or connect a device. Otherwise app may fail to launch.
info Installing the app...
> Configure project :react-native-firebase_app
:react-native-firebase_app package.json found at /Users/asakoulas/BODYBOX/Bodybox/node_modules/@react-native-firebase/app/package.json
:react-native-firebase_app:firebase.bom using default value: 28.1.0
:react-native-firebase_app:play.play-services-auth using default value: 19.0.0
:react-native-firebase_app package.json found at /Users/asakoulas/BODYBOX/Bodybox/node_modules/@react-native-firebase/app/package.json
:react-native-firebase_app:version set from package.json: 12.1.0 (12,1,0 - 12001000)
:react-native-firebase_app:android.compileSdk using custom value: 29
:react-native-firebase_app:android.targetSdk using custom value: 29
:react-native-firebase_app:android.minSdk using custom value: 21
:react-native-firebase_app:reactNativeAndroidDir /Users/myuser/appname/appname/node_modules/react-native/android
Mapping new ns http://schemas.android.com/repository/android/common/02 to old ns http://schemas.android.com/repository/android/common/01
Mapping new ns http://schemas.android.com/repository/android/generic/02 to old ns http://schemas.android.com/repository/android/generic/01
Mapping new ns http://schemas.android.com/sdk/android/repo/addon2/02 to old ns http://schemas.android.com/sdk/android/repo/addon2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/repository2/02 to old ns http://schemas.android.com/sdk/android/repo/repository2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/sys-img2/02 to old ns http://schemas.android.com/sdk/android/repo/sys-img2/01
Mapping new ns http://schemas.android.com/repository/android/common/02 to old ns http://schemas.android.com/repository/android/common/01
Mapping new ns http://schemas.android.com/repository/android/generic/02 to old ns http://schemas.android.com/repository/android/generic/01
Mapping new ns http://schemas.android.com/sdk/android/repo/addon2/02 to old ns http://schemas.android.com/sdk/android/repo/addon2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/repository2/02 to old ns http://schemas.android.com/sdk/android/repo/repository2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/sys-img2/02 to old ns http://schemas.android.com/sdk/android/repo/sys-img2/01
Checking the license for package Android SDK Build-Tools 30.0.2 in /Users/username/Library/Android/sdk/licenses
License for package Android SDK Build-Tools 30.0.2 accepted.
Preparing "Install Android SDK Build-Tools 30.0.2 (revision: 30.0.2)".
"Install Android SDK Build-Tools 30.0.2 (revision: 30.0.2)" ready.
Installing Android SDK Build-Tools 30.0.2 in /Users/asakoulas/Library/Android/sdk/build-tools/30.0.2
"Install Android SDK Build-Tools 30.0.2 (revision: 30.0.2)" complete.
"Install Android SDK Build-Tools 30.0.2 (revision: 30.0.2)" finished.
Mapping new ns http://schemas.android.com/repository/android/common/02 to old ns http://schemas.android.com/repository/android/common/01
Mapping new ns http://schemas.android.com/repository/android/generic/02 to old ns http://schemas.android.com/repository/android/generic/01
Mapping new ns http://schemas.android.com/sdk/android/repo/addon2/02 to old ns http://schemas.android.com/sdk/android/repo/addon2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/repository2/02 to old ns http://schemas.android.com/sdk/android/repo/repository2/01
Mapping new ns http://schemas.android.com/sdk/android/repo/sys-img2/02 to old ns http://schemas.android.com/sdk/android/repo/sys-img2/01
WARNING:: The specified Android SDK Build Tools version (28.0.3) is ignored, as it is below the minimum supported version (30.0.2) for Android Gradle Plugin 4.2.2.
Android SDK Build Tools 30.0.2 will be used.
To suppress this warning, remove "buildToolsVersion '28.0.3'" from your build.gradle file, as each version of the Android Gradle Plugin now has a default version of the build tools.
WARNING:: The specified Android SDK Build Tools version (28.0.3) is ignored, as it is below the minimum supported version (30.0.2) for Android Gradle Plugin 4.2.2.
Android SDK Build Tools 30.0.2 will be used.
To suppress this warning, remove "buildToolsVersion '28.0.3'" from your build.gradle file, as each version of the Android Gradle Plugin now has a default version of the build tools.
> Task :app:installDebug FAILED
Skipping device 'emulator-5554' (emulator-5554): Device is OFFLINE.
134 actionable tasks: 2 executed, 132 up-to-date
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:installDebug'.
> com.android.builder.testing.api.DeviceException: No online devices found.
* 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 14s
error Failed to install the app. Make sure you have the Android development environment set up: https://reactnative.dev/docs/environment-setup.
Error: Command failed: ./gradlew app:installDebug -PreactNativeDevServerPort=8081
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:installDebug'.
> com.android.builder.testing.api.DeviceException: No online devices found.
* 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 14s
at makeError (/Users/username/Appname/app/node_modules/@react-native-community/cli-platform-android/node_modules/execa/index.js:174:9)
at /Users/username/Appname/app/node_modules/@react-native-community/cli-platform-android/node_modules/execa/index.js:278:16
at processTicksAndRejections (internal/process/task_queues.js:95:5)
at async runOnAllDevices (/Users/username/Appname/app/node_modules/@react-native-community/cli-platform-android/build/commands/runAndroid/runOnAllDevices.js:94:5)
at async Command.handleAction (/Users/username/Appname/app/node_modules/@react-native-community/cli/build/index.js:186:9)
info Run CLI with --verbose flag for more details.
在我尝试集成 Firebase 并更新 Android Studio 之前，该命令 (react-native run-android) 运行良好。
我尝试做一些事情来解决这个问题，比如重新安装 android studio 或更新 sdk 工具。
当我运行（react-native run-android）时，JS服务器运行成功，安卓模拟器打开但没有下载应用。
当我在终端中运行：adb devices 时，我得到：
List of devices attached
emulator-5554 offline
我已经尝试过删除、冷重启、重启模拟器，但是没有用，总是显示offline。
非常感谢您的帮助。
提前致谢！
【问题讨论】：
标签： android react-native android-studio android-emulator adb