title: How to get current logged user in Google app engine
body: <p>i developing a application in spring framework  for get current user  in gmail  use</p>
  
  <pre><code> UserService userService = UserServiceFactory.getUserService();
              User user = userService.getCurrentUser(); 
  </code></pre>
  
  <p>but when the user sign out with gmail and new user log in the code return old user .
  how to clear spring chache.</p>