How it works...

An important thing that we did for this recipe was to bind the application users to their respective connection with the OAuth 2.0 Provider (Google in this case). It's important because by doing so, we have a connection per user, unlike the other recipes using Spring Social. But instead of allowing users to register themselves to the social-google1 application, we are using an in-memory model using pre-defined user credentials, as presented in the following code:

auth.inMemoryAuthentication() 
   .withUser("adolfo").password("123").authorities("USER") 
   .and() 
   .withUser("jujuba").password("123").authorities("USER");

So, when running the application and pointing your browser to http://localhost:8080, you must be prompted by an authentication form, as follows.

Enter one of the credentials we declared within the SecurityConfiguration class and click on the Login button, which will lead you to the following page:

This is the page where you might choose to connect with Google by clicking on Connect to Google, which will redirect you to Google's authentication and authorization form as presented in the following screenshot:

Authenticate yourself and grant all the requested permissions and you will be redirected back to the connected page:

Click on the link here and you will be redirected to the profile's HTML view which will retrieve your name from the Google Plus API. Now, if you go to http://localhost:8080/logout, you will be logged out, as you might expect, and if you try to log in with another user you will have to start a new connection flow proving that you have a connection per logged user.