public class AuthFilter implements Filter {
  @Override
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    HttpServletRequest req = (HttpServletRequest)request;
    HttpServletResponse res = (HttpServletResponse)response;
    ConfigProperties config = SpringUtil.getBean(ConfigProperties.class);
    ...
    if (cookie) {
// 查看用户数据是否存在；用户是否禁用，更新用户使用时间点
      chain.doFilter(request, response);
    } else {
      response.getWriter().write("no authenticate");
      res.setStatus(HttpStatus.UNAUTHORIZED.value());
    }
  }
}
// 然后在FilterConfig中进行绑定，并设置中间件前后置
@Configuration
public class FilterConfig {
  @Bean public FilterRegistrationBean registerAuthFilter() {
    FilterRegistrationBean<AuthFilter> registration = new FilterRegistrationBean<>();
    registration.setFilter(new AuthFilter());
    registration.addUrlPatterns("/*");
    registration.setName("AuthFilter");
    registration.setOrder(1);
    return registration;
  }
}

// 先创建一个annotation:
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RoutePermissions {
  String permissions() default "public";
}
// 创建一个interceptor
public class RoutePermissionsInterceptor implements HandlerInterceptor {
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    RoutePermissions routePermissions = null;
    if (handler instanceof HandlerMethod) {
      routePermissions = (RoutePermissions)((HandlerMethod)handler).getMethodAnnotation(RoutePermissions.class);
      // 如果该配置项没有permissions, 默认为admin，谁都可以进入
      // TODO 该用户是否为admin
      if (routePermissions == null) {
        return true;
      }
      String permissions = routePermissions.permissions();
      if (!StringUtils.isEmpty(permissions)) {
        // TODO logic
        // 判断是否有权限
        return true;
      } else {
        response.getWriter().write("no permissions");
        response setStatus(HttpStatus.FORBIDDEN.value());
        return false;
      }
    }
    return true;
  }
}
// 最后在WebMvcConf中注册下
@Configuration
public class WebMvcConf implements WebMvcConfigurer {
  @Bean public RoutePermissionsInterceptor myRoutePermissionInterceptor() {
    RoutePermissionsInterceptor interceptor = new RoutePermissionsInterceptor();
    return interceptor;
  }
  @Override public void addInterceptor(InterceptorRegistry registry) {
    registry.addInterceptor(myRoutePermissionInterceptor());
    ...registry.addInterceptor(...other interceptors);
  }
}

List<String> list = new ArrayList<>();
list.add("a");
list.add("b");
list.add("c");
list.forEach(System.out::println);

// 其中list.forEach可以改写成以下代码:
for (int i = 0; i < list.size(); i++) {
  System.out.println(list.get(i));
}
// 或者等于以下代码:
for (String s : list) {
  System.out.println(s);
}

@FunctionalInterface
public interface FuncA {
  void doSomething(String str);
}