i am using the facebook android sdk, which i just downloaded from github.
i understand that the access token is just valid for a very limited time and needs to be exten
The facebook android sdk make a connection to the refresh token service to extend the access token, but the service is part of Facebook android app, which means that your app user needs to install native Facebook first.
Alternative:
You can use graph api /auth/access_token described in developers.facebook.com/docs/offline-access-deprecation/
I try the request from facebook iOS SDK and it works:
GET api.facebook.com/method/auth.extendSSOAccessToken?access_token=
or in json format. GET api.facebook.com/method/auth.extendSSOAccessToken?format=json&access_token=
Please prefix https:// to all the urls above.