You might want to authenticate the user using one of the google account already configured in your device like some of the apps do, for that follow the below link –
“Authenticating to OAuth2 Services” – http://developer.android.com/training/id-auth/authenticate.html
Download Sample from Google – Android SDK Manager/Extras/Google Play Services
In simple steps it does
- Shows list of accounts in your mobile
- Generates access token from selected accounts
- Gets the Account name from access token by contacting google services(seperate call) to just tell that it has authenticated.
This is another link which is good in explaining the process –
http://android-developers.blogspot.in/2013/01/verifying-back-end-calls-from-android.html
you can follow below steps for Login in your app
- you will send the generated access token to your Back-end server
- Back-end server checks that access token is valid or not by contacting google services by this url “https://www.googleapis.com/oauth2/v1/userinfo?access_token=ACCESS_TOKEN“
- Next Back-end server responds to app whether to make the user login or not.
Below is response format of above “userinfo” call
{
"id": "ID",
"name": "NAME",
"given_name": "GiVEN NAME",
"family_name": "FAMILY_NAME",
"link": "https://plus.google.com/ID",
"picture": "https://PHOTO.jpg",
"gender": "GENDER",
"locale": "LOCALE"
}
If you want Email id along with that response you have to modify
SCOPE = “oauth2:https://www.googleapis.com/auth/userinfo.profile“;
to
SCOPE = “oauth2:https://www.googleapis.com/auth/userinfo.profile https://www.googleapis.com/auth/userinfo.email“;
in that sample