//微服务全局登录用户id注解如配置.java


// 定义 登录用户id 注解
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface LoginUserid {

   
    boolean required() default true;

}

// springcloud-gateway
//实现GlobalFilter接口，在 filter 接口鉴权通过之后，
//将用户信息用 Base64 encode之后，置于ServerWebExchange中，方便微幅端接收.
 public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();
        HttpHeaders httpHeaders = request.getHeaders();
        String token = httpHeaders.getFirst("usr-token");
       
        if (!StringUtils.isEmpty(token)) { 
            String authHeaderUid = Base64.getEncoder().encodeToString(String.valueOf(userId).getBytes(StandardCharsets.UTF_8)); 
            ServerHttpRequest shr = exchange.getRequest().mutate().
                    header("Authorized-UserId", new String[]{authHeaderUid}).build(); 
            return chain.filter(exchange.mutate().request(shr).build());
        }

        return loginRequired(exchange.getResponse()); // 提示登录 
    }


/*
 定义 userid 解析器，其做用是解析 来自 微服务网关中
预编码过的用户id字符串（请求头中），方便各个具体的微服务
模块中各个 action (controller) 直接使用 userId;
*/
public class LoginUserHandlerMethodArgumentResolver implements org.springframework.web.method.support.HandlerMethodArgumentResolver {


    @Override
    public boolean supportsParameter(MethodParameter methodParameter) {
        return methodParameter.hasParameterAnnotation(LoginUserid.class);
    }

    @Override
    public Object resolveArgument(MethodParameter methodParameter, ModelAndViewContainer modelAndViewContainer,
                                  NativeWebRequest nativeWebRequest, WebDataBinderFactory webDataBinderFactory) throws Exception {
        String encodedUserId = nativeWebRequest.getHeader("Authorized-UserId"); // passed from gateway
        if (StringUtils.isEmpty(hashedUserId)) return null;
        Long userId = Long.parseLong(new String(Base64.getDecoder().decode(encodedUserId)));
        return userId;
    }

}


 
// 例如
// 在 user-service 微服务中 进行如下配置
@Configuration
public class serWebMvcConfig implements WebMvcConfigurer {

   @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(new LoginUserHandlerMethodArgumentResolver());
    }
	
}


@RestController
public class UserControllerStub {



    @GetMapping("/echo")
    public Map<String, Object> echo(@LoginUserid Long uid) {
        System.out.println("echo() runs : " + uid);
        return Map.of();
    }


}