java实现自定义免登录注解@LoginNotRequired，可加在controller或接口方法（需要登录也同理）

如何实现给接口或Controller加上我自己的注解就能让他必须登录或者不需要登录就能访问呢？

    @RequestMapping("/test2")
    @LoginNotRequired
    public String test2() {
        return "test2";
    }

@RestController
@RequestMapping("user")
@LoginNotRequired
public class UserController {
}

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
public @interface LoginNotRequired {
}

我们实现可能有所不同，但是道理是一样的，就是定义一个intercepto（ implements HandlerInterceptor）拦截掉所有请求，在请求被处理器执行之前(preHandle)就去执行我们的鉴权操作

@Component
@Slf4j
public class UserLoginInterceptor implements HandlerInterceptor {
    @Autowired
    private IUserAuthUtil userAuthUtil;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        boolean loginNotRequired = false;
        if (handler instanceof HandlerMethod) {
            //转换对象
            HandlerMethod handlerMethod = (HandlerMethod) handler;
            //controller类
            Class controllerClass = handlerMethod.getBean().getClass();
            //类上有没有免登录注解
            boolean controllerHasLoginNotRequired = controllerClass.isAnnotationPresent(LoginNotRequired.class);
            if (controllerHasLoginNotRequired) {
                loginNotRequired = true;
            }

            //方法上有没有免登录注解
            boolean methodHasLoginNotRequired = handlerMethod.hasMethodAnnotation(LoginNotRequired.class);
            if (methodHasLoginNotRequired) {
                loginNotRequired = true;
            }

            //检验登录的token
            String token = request.getHeader(IUserAuthUtil.HEADER_NAME);
            if (!StringUtils.isEmpty(token)) {
                //有token

                //token格式不对
                BusinessAssert.isTrue(userAuthUtil.checkTokenFormat(token), CommonErrorEnums.LOGIN_INVALID);
                //检查token
                Long userId = userAuthUtil.checkToken(token);
                //没登录(免登录)
                BusinessAssert.isTrue(loginNotRequired || !(userId == IUserAuthUtil.NOT_LOGIN), CommonErrorEnums.NEED_LOGIN);
                //登录失效
                BusinessAssert.isTrue(!(userId == IUserAuthUtil.LOGIN_INVALID), CommonErrorEnums.LOGIN_INVALID);
                if (userId > 0) {
                    //获取用户信息
                    User user = userAuthUtil.getUserFromRedis(userId);
                    //设置到request attribute里
                    request.setAttribute(IUserAuthUtil.LOGINED_USER, user);
                }
            } else {
                //没有token又没有免登录就打回
                BusinessAssert.isTrue(loginNotRequired, CommonErrorEnums.NEED_LOGIN);
            }
        }

        return true;
    }
}

@Configuration
public class WebMvcConfiguration implements WebMvcConfigurer {
    @Autowired
    private UserLoginInterceptor userLoginInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //拦截所有请求做登录检查
        registry.addInterceptor(userLoginInterceptor).addPathPatterns("/**");
    }
}