1、安裝中文官網安裝Flutter，然后一直卡在pub upgrade，后來配置了URL：
2、但執行flutter doctor還是報錯：[!] Android toolchain - develop for Android devices
3、然后配置AS的環境變量，仍然報錯；而且發覺SDK目錄下並沒tools文件夾；因此懷疑是不是因為工具更新，舍棄了該文件夾；
4、按照此方向，谷歌后得到了解決方案：
You need to open AndroidStudio then go to Tools -> SDK Manager then go to SDK Tools tab, uncheck the option Hide Obsolete Packages
You will see the option of Android SDK Tools (Obsolete), check the option and continue the process download and installation.
https://stackoverflow.com/questions/52256569/android-sdkmanager-tool-not-found
5、大功告成！！
