If the user is logged in, this method will return a User that
contains information about him.
Returns true if a user is logged in, otherwise returns false.
Table 6-2. Major methods in the User class
Return this user's nickname. The nickname will be a
unique, human- readable identifier (for example, an
e-mail address) for this user with respect to this
application. It will be an email address for some users,
but not all.
Domain name into which this user has authenticated, or
"gmail.com" for normal Google authentication.
The user's e-mail address.
Google makes it easy to simulate its Accounts service by providing a dummy sign-in
screen (see Figure 6-1) while you are developing your application. When your
application requires authentication, it obtains a URL for the sign-in screen from the
Users API. App Engine returns a special development URL and presents you with a
dummy sign-in form that requires an e-mail address but no password. You can enter
any e-mail address you'd like, and your application will execute just as it would if
actually authenticating against Google Accounts. This sign-in screen also includes a
check box so that you can simulate signing in as an administrator.
Once signed in, you can use the Users API to obtain a sign-out URL that cancels
your dummy session.