Warning: License for package Android SDK Build-Tools 28.0.3 not accepted解決辦法

Launching lib/main.dart on sdk gphone x86 in debug mode...
Running Gradle task 'assembleDebug'...
Checking the license for package Android SDK Build-Tools 28.0.3 in /Users/*/Library/Android/sdk/licenses
Warning: License for package Android SDK Build-Tools 28.0.3 not accepted.
Checking the license for package Android SDK Platform 28 in /Users/*/Library/Android/sdk/licenses
Warning: License for package Android SDK Platform 28 not accepted.

FAILURE: Build failed with an exception.

* What went wrong:
Could not determine the dependencies of task ':app:compileDebugJavaWithJavac'.
> Failed to install the following Android SDK packages as some licences have not been accepted.
     build-tools;28.0.3 Android SDK Build-Tools 28.0.3
     platforms;android-28 Android SDK Platform 28
  To build this project, accept the SDK license agreements and install the missing components using the Android Studio SDK Manager.
  Alternatively, to transfer the license agreements from one workstation to another, see http://d.android.com/r/studio-ui/export-licenses.html

  Using Android SDK: /Users/*/Library/Android/sdk

* 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 12s
Finished with error: Gradle task assembleDebug failed with exit code 1

打開sdk目錄

$cd /Users/*/Library/Android/sdk/tools/bin
./sdkmanager --licenses

然後一路y到底

如果報錯

Exception in thread "main" java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema
	at com.android.repository.api.SchemaModule$SchemaModuleVersion.<init>(SchemaModule.java:156)
	at com.android.repository.api.SchemaModule.<init>(SchemaModule.java:75)
	at com.android.sdklib.repository.AndroidSdkHandler.<clinit>(AndroidSdkHandler.java:81)
	at com.android.sdklib.tool.sdkmanager.SdkManagerCli.main(SdkManagerCli.java:73)
	at com.android.sdklib.tool.sdkmanager.SdkManagerCli.main(SdkManagerCli.java:48)
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.annotation.XmlSchema
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:602)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
	... 5 more

則通常是jdk版本高，JAXB API是java EE 的API，在java SE 9.0 中不再包含這個 Jar 包。但是 java 6/7 / 8 時關於這個API 都是打包在一起的。