O, Auth me mighty Google!
First things first, we need to be able to talk to Google. Remember that googleAuthorization page we mentioned earlier? Let's make it! (Refer to Chapter 5, Visualforce Development with Apex, if you forgot how, or skipped). Short version: right-click on Project in Eclipse and navigate to New | Visualforce Page and name it accordingly. While we're at it, let's make the corresponding controller, googleAuthorization_Controller
(navigate to New | Apex Class for this).
Let's start with our code for the controller. We're going to need a holder variable for the Google e-mail that we are authenticating and a button to initiate the process. Now, remember how we talked about using a different e-mail than the user e-mail? Although that is a potential use case, if it's not we should just prepopulate this with the user info anyway. Ok, so here is our powerful little page, packed full of little goodies! (Don't worry about the giant regular expression, you can get that from the code...