如何在Spring Security的JdbcAuthentication中从数据库中获取用户数据？

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    private DataSource dataSource;

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.jdbcAuthentication()
                .dataSource(dataSource)
                .usersByUsernameQuery("SELECT username, password, enabled FROM users WHERE username = ?")
                .authoritiesByUsernameQuery("SELECT username, authority FROM authorities WHERE username = ?");
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
                .antMatchers("/admin/**").hasRole("ADMIN")
                .antMatchers("/user/**").hasAnyRole("ADMIN", "USER")
                .anyRequest().authenticated()
                .and()
                .formLogin().permitAll()
                .and()
                .logout().permitAll();
    }
}