<div class="container authenticated" style="display:none">
    Logged in as: <span id="user"></span>
</div>


<script type="text/javascript">
    $.get("/user", function(data) {
        $("#user").html(data.name);
        $(".unauthenticated").hide()
        $(".authenticated").show()
    });
</script>

@Configuration
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
                .authorizeRequests(a -> a
                        .antMatchers("/", "/error", "/webjars/**").permitAll()
                        .anyRequest().authenticated()
                )
                .exceptionHandling(e -> e
                        .authenticationEntryPoint(new HttpStatusEntryPoint(HttpStatus.UNAUTHORIZED))
                )
                .oauth2Login();
    }
}

@SpringBootApplication
@RestController
public class Demo13Application {

	public static void main(String[] args) {
		SpringApplication.run(Demo13Application.class, args);
	}


    @GetMapping("/user")
    public Map<String, Object> user(@AuthenticationPrincipal OAuth2User principal) {
        return Collections.singletonMap("name", principal.getAttribute("name"));
    }

}