In a web application, it can be useful to get the logged on user's name and display it within a web page, for example as a link to allow the user to edit their profile.  In a Spring Web application the username can easily be obtained in a controller and passed via a map to the user interface.

To get the username in a controller class, we would use the SecurityContextHolder.getContext().getAuthentication().getPrincipal() method to get hold of the principal. We can then call the .getUsername() method to get the username of the currently logged on user.

@Controller
public class PageController {
 
  @RequestMapping(method = RequestMethod.GET)
 
  public ModelAndView handleRequest() {
    User user = (User) SecurityContextHolder.getContext()
        .getAuthentication().getPrincipal();
    Map<String, Object> userModel = new HashMap<String, Object>();
    userModel.put("username", user.getUsername());
    return new ModelAndView("page", "model", userModel);
  }
}

<c:out value="${model.username}" />

From http://www.davidsalter.com/2012/01/getting-logged-on-user-in-spring-web.html