authentication.getPrincipal（）始终是String而不是UserDetails

Question

在我WebSecurityConfigurerAdapter有这个：

@Bean
public DaoAuthenticationProvider daoAuthenticationProvider() {
    DaoAuthenticationProvider daoAuthenticationProvider = new DaoAuthenticationProvider();
    daoAuthenticationProvider.setPasswordEncoder(passwordEncoder());
    daoAuthenticationProvider.setUserDetailsService(this.userDetailsService);
    return daoAuthenticationProvider;
}

以及以下内容UserDetailsService：

@Service
public class AppUserDetailsService implements UserDetailsService {

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {

        AppUserEntity appUserEntity = this.appUserRepository.findByUsername(username).orElseThrow(() ->
            new ResourceNotFoundException("Current user not found."));

        return new AppUserDetails(appUserEntity);
    }

}

但是，我无法AppUserDetails implements UserDetails使用

Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
// Throws exception because the principal is a String
AppUserDetails appUserDetails = (AppUserDetails) authentication.getPrincipal();

因为authentication.getPrincipal()总是返回一个String（在这种情况下为用户的用户名）。但是，我希望它返回一个AppUserDetails。为什么不是这种情况，我该如何更改？

---

我试过了

SecurityContextHolder.getContext().getAuthentication().getDetails()

但这又回来了，OAuth2AuthenticationDetails而不是UserDetails我所希望的。

---

尝试此操作也不起作用。返回的details对象是null。

OAuth2Authentication oAuth2Authentication =
                (OAuth2Authentication) SecurityContextHolder.getContext().getAuthentication();

Authentication userAuthentication = oAuth2Authentication.getUserAuthentication();

Object details = userAuthentication.getDetails();