问题
I have download Android Studio packed with the full SDK (build-tools, platforms, everything). Installed the studio (64-bit) on Drive C and the SDK in "AppData/local/Android/android-sdk" folder as specified by the installer itself. Now when I run the Studio (with admin permissions) it still attempts to download everything, as if no SDK components were present on my PC. Is there a way to tell the Studio where the SDK is? Or I have to re-download it all?? (I already have everything mentioned in the error message)
"The following SDK components were not installed: platform-tools, extra-android-m2repository, tools, addon-google_apis-google-21, build-tools-21.1.2, android-21, sys-img-x86-addon-google_apis-google-21, source-21,"
回答1:
[The following SDK component was not installed: platform-tools]
I ran into the same issue and was able to solve it by updating the SDK from the command line. Go to the location where your Android SDK was installed (possibly ~/Android/Sdk) and run:
./android update sdk --no-ui
There's no need to run it as root.
Then, on Android Studio, go on Configure -> Project Defaults -> Project Structure, and then point Android SDK Location to wherever it is located.
回答2:
step1: just copy 21.1.2 folder and paste with name 21.1.1
step2 : open 21.1.1 folder and open "source properties" file with any text editor( notepad)
step3 : change pkg.Revision=21.1.1 save it
step 4: android studio
回答3:
sudo chown -R <username> .android
as mentioned here, android sdk updater stores a copy of some xmls in .android/cache
So after you have set the permissions, the updater can store necessary xmls and download missing sdk components
来源：https://stackoverflow.com/questions/28123294/android-studio-doesnt-start-up-saying-sdk-components-were-not-installed