How to find out the currently logged-in user in Spring Boot?

As per request:

Spring Boot which uses Spring Security internally provides a SecurityContextHolder class which allows the lookup of the currently authenticated user via:

Authentication auth = SecurityContextHolder.getContext().getAuthentication();

The authentication instance now provides the following methods:

Get the username of the logged in user: getPrincipal()

Get the password of the authenticated user: getCredentials()

Get the assigned roles of the authenticated user: getAuthorities()

Get further details of the authenticated user: getDetails()

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Since Spring Security 3.2 you can get currently logged in user (your implementation of UserDetails) by adding a parameter inside your controller method:

import org.springframework.security.web.bind.annotation.AuthenticationPrincipal;

@RequestMapping("/resource")
public Map<String, Object> home(@AuthenticationPrincipal User user) {
   ..
}

Replace User with the name of your class which implements UserDetails interface.

Edit:

Since Spring Security 4.0 annotation was moved to a different package:

import org.springframework.security.core.annotation.AuthenticationPrincipal;

Addendum:

This will work even in WebFlux reactive environment versus the SecurityContextHolder.getContext().getAuthentication() which won't work because of paradigm shift from thread per request model to multiple requests per thread.

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You can simply use HttpServletRequest also to get user principle,

using HttpServletRequest request,

String user=request.getUserPrincipal().getName();

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One way is to add java.security.Principal as a parameter as follows:

@RequestMapping("/resource")
public Map<String, Object> home(Principal principal) {
    Map<String, Object> model = new HashMap<String, Object>();
    model.put("id", UUID.randomUUID().toString());
    model.put("content", "Hello " + principal.getName());
    return model;
}

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Since version 5.2 you can use CurrentSecurityContext annotation:

@GetMapping("/hello")
public String hello(@CurrentSecurityContext(expression="authentication?.name")
                    String username) {
    return "Hello, " + username + "!";
}

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In Spring boot v2.1.9.RELEASE if you are trying to get the name, email , given_name you can get those details from Pricipal. Note: I am using spring security with google oauth2

Map<String , Object> userDetails = ((DefaultOidcUser)SecurityContextHolder.getContext().getAuthentication().getPrincipal()).getAttributes(); System.out.println(userDetails.get("name")); System.out.println(userDetails.get("email")); System.out.println(userDetails.get("given_name"));

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Recently using Keycloak authentication server and accessing currently logged-in user data is accessible like this

String userID;

KeycloakPrincipal kcPrincipal = getPrincipal();
KeycloakSecurityContext ksContext = kcPrincipal.getKeycloakSecurityContext();
IDToken idToken = ksContext.getToken();
userID = idToken.getName();

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Im using spring boot 2.0 with OAuth so I'm doing it like this

Authentication auth = SecurityContextHolder.getContext().getAuthentication();
Object pricipal = auth.getPrincipal();
String user="";
if (pricipal instanceof DefaultOidcUser) {
       user = ((DefaultOidcUser) pricipal).getName();
}

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You can find the currently logged in user name without using any spring Security features. All you need is a jdk 1.8

Do the following :

@RequestMapping("/login")
@Override
public ModelAndView AuthChecker(@RequestParam("email") String email, @RequestParam("password") String password, Customers cust) {

     ModelAndView mv = new ModelAndView("index");
     if((repo.findByEmail(email)!=null) && (repo.findByPassword(password)!=null)) {
        
         
      List<Customers> l=  repo.findAll();
      
      cust = (Customers) l.stream() 
      .filter(x -> email.equals(x.getEmail()))        
      .findAny()                                      
      .orElse(null); 
    
        mv.addObject("user",cust.getName());
         mv.setViewName("DashBoardRedirect");
    
         return mv;

Once name fetched successfully, you can use the same in any jsp/thymeleaf view.

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