SecurityContextHolder导入在spring boot应用程序中不起作用

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .antMatchers("/admin/**").hasRole("ADMIN")
                .antMatchers("/user/**").hasAnyRole("ADMIN", "USER")
                .anyRequest().authenticated()
                .and()
            .formLogin()
                .and()
            .logout()
                .and()
            .csrf().disable();
    }
    
    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth
            .inMemoryAuthentication()
                .withUser("admin").password("{noop}admin").roles("ADMIN")
                .and()
                .withUser("user").password("{noop}user").roles("USER");
    }
}

Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
String username = authentication.getName();