How to get active user's UserDetails

Question

Preamble: Since Spring-Security 3.2 there is a nice annotation @AuthenticationPrincipal described at the end of this answer. This is the best way to go when you use Spring-Security >= 3.2.

When you:

• use an older version of Spring-Security,
• need to load your custom User Object from the Database by some information (like the login or id) stored in the principal or
• want to learn how a HandlerMethodArgumentResolver or WebArgumentResolver can solve this in an elegant way, or just want to an learn the background behind @AuthenticationPrincipal and AuthenticationPrincipalArgumentResolver (because it is based on a HandlerMethodArgumentResolver)

then keep on reading — else just use @AuthenticationPrincipal and thank to Rob Winch (Author of @AuthenticationPrincipal) and Lukas Schmelzeisen (for his answer).

(BTW: My answer is a bit older (January 2012), so it was Lukas Schmelzeisen that come up as the first one with the @AuthenticationPrincipal annotation solution base on Spring Security 3.2.)

---

Then you can use in your controller

public ModelAndView someRequestHandler(Principal principal) {
   User activeUser = (User) ((Authentication) principal).getPrincipal();
   ...
}

---

That is ok if you need it once. But if you need it several times its ugly because it pollutes your controller with infrastructure details, that normally should be hidden by the framework.

So what you may really want is to have a controller like this:

public ModelAndView someRequestHandler(@ActiveUser User activeUser) {
   ...
}

Therefore you only need to implement a WebArgumentResolver. It has a method

Object resolveArgument(MethodParameter methodParameter,
                   NativeWebRequest webRequest)
                   throws Exception

That gets the web request (second parameter) and must return the User if its feels responsible for the method argument (the first parameter).

Since Spring 3.1 there is a new concept called HandlerMethodArgumentResolver. If you use Spring 3.1+ then you should use it. (It is described in the next section of this answer))

public class CurrentUserWebArgumentResolver implements WebArgumentResolver{

   Object resolveArgument(MethodParameter methodParameter, NativeWebRequest webRequest) {
        if(methodParameter is for type User && methodParameter is annotated with @ActiveUser) {
           Principal principal = webRequest.getUserPrincipal();
           return (User) ((Authentication) principal).getPrincipal();
        } else {
           return WebArgumentResolver.UNRESOLVED;
        }
   }
}

You need to define the Custom Annotation -- You can skip it if every instance of User should always be taken from the security context, but is never a command object.

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ActiveUser {}

In the configuration you only need to add this:

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"
    id="applicationConversionService">
    <property name="customArgumentResolver">
        <bean class="CurrentUserWebArgumentResolver"/>
    </property>
</bean>

@See: Learn to customize Spring MVC @Controller method arguments

It should be noted that if you're using Spring 3.1, they recommend HandlerMethodArgumentResolver over WebArgumentResolver. - see comment by Jay

---

The same with HandlerMethodArgumentResolver for Spring 3.1+

public class CurrentUserHandlerMethodArgumentResolver
                               implements HandlerMethodArgumentResolver {

     @Override
     public boolean supportsParameter(MethodParameter methodParameter) {
          return
              methodParameter.getParameterAnnotation(ActiveUser.class) != null
              && methodParameter.getParameterType().equals(User.class);
     }

     @Override
     public Object resolveArgument(MethodParameter methodParameter,
                         ModelAndViewContainer mavContainer,
                         NativeWebRequest webRequest,
                         WebDataBinderFactory binderFactory) throws Exception {

          if (this.supportsParameter(methodParameter)) {
              Principal principal = webRequest.getUserPrincipal();
              return (User) ((Authentication) principal).getPrincipal();
          } else {
              return WebArgumentResolver.UNRESOLVED;
          }
     }
}

In the configuration, you need to add this

<mvc:annotation-driven>
      <mvc:argument-resolvers>
           <bean class="CurrentUserHandlerMethodArgumentResolver"/>         
      </mvc:argument-resolvers>
 </mvc:annotation-driven>

@See Leveraging the Spring MVC 3.1 HandlerMethodArgumentResolver interface

---

Spring-Security 3.2 Solution

Spring Security 3.2 (do not confuse with Spring 3.2) has own build in solution: @AuthenticationPrincipal (org.springframework.security.web.bind.annotation.AuthenticationPrincipal) . This is nicely described in Lukas Schmelzeisen`s answer

It is just writing

ModelAndView someRequestHandler(@AuthenticationPrincipal User activeUser) {
    ...
 }

To get this working you need to register the AuthenticationPrincipalArgumentResolver (org.springframework.security.web.bind.support.AuthenticationPrincipalArgumentResolver) : either by "activating" @EnableWebMvcSecurity or by registering this bean within mvc:argument-resolvers - the same way I described it with may Spring 3.1 solution above.

@See Spring Security 3.2 Reference, Chapter 11.2. @AuthenticationPrincipal

---

Spring-Security 4.0 Solution

It works like the Spring 3.2 solution, but in Spring 4.0 the @AuthenticationPrincipal and AuthenticationPrincipalArgumentResolver was "moved" to an other package:

• org.springframework.security.core.annotation.AuthenticationPrincipal
• org.springframework.security.web.method.annotation.AuthenticationPrincipalArgumentResolver

(But the old classes in its old packges still exists, so do not mix them!)

It is just writing

import org.springframework.security.core.annotation.AuthenticationPrincipal;
ModelAndView someRequestHandler(@AuthenticationPrincipal User activeUser) {
    ...
}

To get this working you need to register the (org.springframework.security.web.method.annotation.) AuthenticationPrincipalArgumentResolver : either by "activating" @EnableWebMvcSecurity or by registering this bean within mvc:argument-resolvers - the same way I described it with may Spring 3.1 solution above.

<mvc:annotation-driven>
    <mvc:argument-resolvers>
        <bean class="org.springframework.security.web.method.annotation.AuthenticationPrincipalArgumentResolver" />
    </mvc:argument-resolvers>
</mvc:annotation-driven>

@See Spring Security 5.0 Reference, Chapter 39.3 @AuthenticationPrincipal

While Ralphs Answer provides an elegant solution, with Spring Security 3.2 you no longer need to implement your own ArgumentResolver.

If you have a UserDetails implementation CustomUser, you can just do this:

@RequestMapping("/messages/inbox")
public ModelAndView findMessagesForUser(@AuthenticationPrincipal CustomUser customUser) {

    // .. find messages for this User and return them...
}

See Spring Security Documentation: @AuthenticationPrincipal

Spring Security is intended to work with other non-Spring frameworks, hence it is not tightly integrated with Spring MVC. Spring Security returns the Authentication object from the HttpServletRequest.getUserPrincipal() method by default so that's what you get as the principal. You can obtain your UserDetails object directly from this by using

UserDetails ud = ((Authentication)principal).getPrincipal()

Note also that the object types may vary depending on the authentication mechanism used (you may not get a UsernamePasswordAuthenticationToken, for example) and the Authentication doesn't strictly have to contain a UserDetails. It can be a string or any other type.

If you don't want to call SecurityContextHolder directly, the most elegant approach (which I would follow) is to inject your own custom security context accessor interface which is customized to match your needs and user object types. Create an interface, with the relevant methods, for example:

interface MySecurityAccessor {

    MyUserDetails getCurrentUser();

    // Other methods
}

You can then implement this by accessing the SecurityContextHolder in your standard implementation, thus decoupling your code from Spring Security entirely. Then inject this into the controllers which need access to security information or information on the current user.

The other main benefit is that it is easy to make simple implementations with fixed data for testing, without having to worry about populating thread-locals and so on.

Implement the HandlerInterceptor interface, and then inject the UserDetails into each request that has a Model, as follows:

@Component 
public class UserInterceptor implements HandlerInterceptor {
    ....other methods not shown....
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        if(modelAndView != null){
            modelAndView.addObject("user", (User)SecurityContextHolder.getContext().getAuthentication().getPrincipal());
        }
}

Starting with Spring Security version 3.2, the custom functionality that has been implemented by some of the older answers, exists out of the box in the form of the @AuthenticationPrincipal annotation that is backed by AuthenticationPrincipalArgumentResolver.

An simple example of it's use is:

@Controller
public class MyController {
   @RequestMapping("/user/current/show")
   public String show(@AuthenticationPrincipal CustomUser customUser) {
        // do something with CustomUser
       return "view";
   }
}

CustomUser needs to be assignable from authentication.getPrincipal()

Here are the corresponding Javadocs of AuthenticationPrincipal and AuthenticationPrincipalArgumentResolver

@Controller
public abstract class AbstractController {
    @ModelAttribute("loggedUser")
    public User getLoggedUser() {
        return (User)SecurityContextHolder.getContext().getAuthentication().getPrincipal();
    }
}