flutter doctor X Android license status unknown.

問題：當在window上搭建flutter開發環境，最後運行flutter doctor -v時，出現提示：

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, v1.9.1+hotfix.5, on Microsoft Windows [Version 10.0.17763.316], locale zh-CN)
[!] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
    X Android license status unknown.
      Try re-installing or updating your Android SDK Manager.
      See https://developer.android.com/studio/#downloads or visit https://flutter.dev/setup/#android-setup for detailed instructions.
[√] Android Studio (version 3.5)
[√] VS Code (version 1.39.2)
[!] Connected device
    ! No devices available

解決方法：

按照提示升級sdk manager

打開命令行窗口，講目錄切換到Android sdk 目錄下：AndroidSdk\tools\bin
運行一下命令

sdkmanager --update

D:\tools\Android\AndroidSdk\tools\bin>sdkmanager --update