How to obtain getUserPrincipal().getUserName() while implementing Spring Data JPA AuditorAware interface - spring

Question

I'm trying to use Spring Data JPA (1.6.2) in my current project. All seems to work well, but I got stuck while implementing the AuditorAware interface.
My application will be deployed to an old Apache Jetspeed JSR168 compliant portal. This portal takes care of user authentication/authorisation. As such, I don't have to use a security framework like Spring Security or Shiro. The other frameworks in my application are:
Struts 1.2.4 (with a Struts-Portal-Bridge)
Spring 3.2.10
JPA (Hibernate 3.6.10 as ORM provider)
I'd like to use #CreatedBy and #LastModifiedBy annotated fields in my entities (I got #CreatedDate and #LastModifiedDate working). In my application I usually obtain the username using request.getUserPrincipal().getUserName().
But how can I get hold of the username while implementing the AuditorAware interface?
The example implementation from the Spring Data JPA docs:
class SpringSecurityAuditorAware implements AuditorAware<User> {
public User getCurrentAuditor() {
Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
if (authentication == null || !authentication.isAuthenticated()) {
return null;
}
return ((MyUserDetails) authentication.getPrincipal()).getUser();
}
}
Somehow I want to implement AuditorAware like this:
class MyAuditorAware implements AuditorAware<String> {
public String getCurrentAuditor() {
return <<principal from servlet- or portletcontext>>.getUserName();
}
}
How can I accomplish this without adding an additional framework?

Answer 1

As Konstantin already mentioned in his comment, you probably want to save the principal name in a scope suitable for a request. This may very well be a ThreadLocal. This allows you to get it easily later on in your AuditorAware implementation.
To stay with Spring's naming call it PrincipalContextHolder. As a starting point you may look at the source of JodaTimeContextHolder for a simple implementation of a ContextHolder.