自定义Gateway全局过滤器实现登录鉴权

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全局过滤器，做登录鉴权

- 如果是注册登录请求，去授权中心获取token

- 如果是其他请求，做 token 解析验证

- 如果是监控、swagger等请求，不需登录，直接放行

/**
 * 
 */
@AllArgsConstructor
@Slf4j
@Component
public class AuthFilter implements GlobalFilter, Ordered {
    /**
     * 注册中心客户端, 可以从注册中心中获取服务实例信息
     */
    private final LoadBalancerClient loadBalancerClient;
    private final RestTemplate restTemplate;

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();
        ServerHttpResponse response = exchange.getResponse();

        // 直接放行，测试版
        if (request.getURI().getPath().contains(GatewayConstant.LOGIN_URI)) {
            return chain.filter(exchange);
        }

        // 1. 如果是登录
        if (request.getURI().getPath().contains(GatewayConstant.LOGIN_URI)) {
            // 去授权中心拿 token
            String token = getTokenFromAuthorityCenter(
                    request, GatewayConstant.AUTHORITY_CENTER_TOKEN_URL_FORMAT
            );
            // header 中不能设置 null
            response.getHeaders().add(
                    CommonConstant.JWT_USER_INFO_KEY,
                    null == token ? "null" : token
            );
            response.setStatusCode(HttpStatus.OK);
            return response.setComplete();
        }

        // 2. 如果是注册
        if (request.getURI().getPath().contains(GatewayConstant.REGISTER_URI)) {
            // 去授权中心拿 token: 先创建用户, 再返回 Token
            String token = getTokenFromAuthorityCenter(
                    request, GatewayConstant.AUTHORITY_CENTER_REGISTER_URL_FORMAT
            );
            response.getHeaders().add(
                    CommonConstant.JWT_USER_INFO_KEY,
                    null == token ? "null" : token
            );
            response.setStatusCode(HttpStatus.OK);
            return response.setComplete();
        }

        // 3. 访问其他的服务, 则鉴权, 校验是否能够从 Token 中解析出用户信息
        HttpHeaders headers = request.getHeaders();
        String token = headers.getFirst(CommonConstant.JWT_USER_INFO_KEY);
        String dev = headers.getFirst("dev");
        if (dev.equals("dev")){
            return chain.filter(exchange);
        }
        LoginUserInfo loginUserInfo = null;

        try {
            loginUserInfo = TokenParseUtil.parseUserInfoFromToken(token);
        } catch (Exception ex) {
            log.error("parse user info from token error: [{}]", ex.getMessage(), ex);
        }

        // 获取不到登录用户信息, 返回 401
        if (null == loginUserInfo) {
            response.setStatusCode(HttpStatus.UNAUTHORIZED);
            return response.setComplete();
        }

        // 解析通过, 则放行
        return chain.filter(exchange);
    }

    /**
     * <h2>从授权中心获取 Token</h2>
     */
    private String getTokenFromAuthorityCenter(ServerHttpRequest request, String uriFormat) {

        // service id 就是服务名字, 负载均衡
        ServiceInstance serviceInstance = loadBalancerClient.choose(
                CommonConstant.AUTHORITY_CENTER_SERVICE_ID
        );
        log.info("Nacos Client Info: [{}], [{}], [{}]", serviceInstance.getServiceId(), serviceInstance.getInstanceId(), JSON.toJSONString(serviceInstance.getMetadata()));

        String requestUrl = String.format(
                uriFormat, serviceInstance.getHost(), serviceInstance.getPort()
        );

        String body = getBodyFromBuffer(request);
        log.info("login request url and body: [{}], [{}]", requestUrl, body);

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON);
        JwtToken token = restTemplate.postForObject(
                requestUrl,
                new HttpEntity<>(body, headers),
                JwtToken.class
        );

        if (null != token) {
            return token.getToken();
        }

        return null;
    }

    private String getBodyFromBuffer(ServerHttpRequest request) {
        // 获取请求体
        Flux<DataBuffer> body = request.getBody();
        AtomicReference<String> bodyRef = new AtomicReference<>();

        // 订阅缓冲区去消费请求体中的数据
        body.subscribe(buffer -> {
            CharBuffer charBuffer = StandardCharsets.UTF_8.decode(buffer.asByteBuffer());
            // 一定要使用 DataBufferUtils.release 释放掉, 否则, 会出现内存泄露
            DataBufferUtils.release(buffer);
            bodyRef.set(charBuffer.toString());
        });

        // 获取 request body
        return bodyRef.get();
    }

    @Override
    public int getOrder() {
        return HIGHEST_PRECEDENCE + 2;
    }
}