快速搭建一个网关服务，动态路由、鉴权看完就会（含流程图）

<parent>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-parent</artifactId>
   <version>2.1.0.RELEASE</version>
</parent>

<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-gateway-core</artifactId>
</dependency>

<dependency>
   <groupId>org.apache.commons</groupId>
   <artifactId>commons-lang3</artifactId>
</dependency>

server:
  port: 8080
spring:
  cloud:
    gateway:
      enabled: true
      routes:
      - id: demo-server
        uri: http://localhost:8081
        predicates:
        - Path=/demo-server/**
        filters:
          - StripPrefix= 1

[{
      "id": "xxx-server",
      "order": 1, #优先级
      "predicates": [{ #路由断言
          "args": {
              "pattern": "/xxx-server/**"
          },
          "name": "Path"
      }],
      "filters":[{ #过滤规则
          "args": {
              "parts": 0 #k8s服务内部访问容器为http://xxx-server/xxx-server的话,配置0即可
          },
          "name": "StripPrefix" #截取的开始索引
      }],
      "uri": "http://localhost:8080/xxx-server" #目标地址
  }]

{
    "id":"demo-server",
    "predicates":[
        {
            "args":{
                "pattern":"/demo-server/**"
            },
            "name":"Path"
        }
    ],
    "filters":[
        {
            "args":{
                "parts":1
            },
            "name":"StripPrefix"
        }
    ],
    "uri":"http://localhost:8081"
}
spring:
  cloud:
    gateway:
      enabled: true
      routes:
      - id: demo-server
        uri: http://localhost:8081
        predicates:
        - Path=/demo-server/**
        filters:
          - StripPrefix= 1

@Component
public class NacosDynamicRouteService implements ApplicationEventPublisherAware {
    private static final Logger LOGGER = LoggerFactory.getLogger(NacosDynamicRouteService.class);
    @Autowired
    private RouteDefinitionWriter routeDefinitionWriter;
    private ApplicationEventPublisher applicationEventPublisher;
    /** 路由id */
    private static List<String> routeIds = Lists.newArrayList();
    /**
     * 监听nacos路由配置，动态改变路由
     * @param configInfo
     */
    @NacosConfigListener(dataId = "routes", groupId = "gateway-server")
    public void routeConfigListener(String configInfo) {
        clearRoute();
        try {
            List<RouteDefinition> gatewayRouteDefinitions = JSON.parseArray(configInfo, RouteDefinition.class);
            for (RouteDefinition routeDefinition : gatewayRouteDefinitions) {
                addRoute(routeDefinition);
            }
            publish();
            LOGGER.info("Dynamic Routing Publish Success");
        } catch (Exception e) {
            LOGGER.error(e.getMessage(), e);
        }
    }
    /**
     * 清空路由
     */
    private void clearRoute() {
        for (String id : routeIds) {
            routeDefinitionWriter.delete(Mono.just(id)).subscribe();
        }
        routeIds.clear();
    }
    @Override
    public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
        this.applicationEventPublisher = applicationEventPublisher;
    }
    /**
     * 添加路由
     * 
     * @param definition
     */
    private void addRoute(RouteDefinition definition) {
        try {
            routeDefinitionWriter.save(Mono.just(definition)).subscribe();
            routeIds.add(definition.getId());
        } catch (Exception e) {
            LOGGER.error(e.getMessage(), e);
        }
    }
    /**
     * 发布路由、使路由生效
     */
    private void publish() {
        this.applicationEventPublisher.publishEvent(new RefreshRoutesEvent(this.routeDefinitionWriter));
    }
}

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis-reactive</artifactId>
</dependency>
spring:
  redis:
    host: redis-server
    port: 6379
    password:
    database: 0

@Component
public class AuthFilter implements GlobalFilter, Ordered {
    @Autowired
    private RedisTemplate<String, String> redisTemplate;
    private static final String TOKEN_HEADER_KEY = "auth_token";
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        // 1.获取请求对象
        ServerHttpRequest request = exchange.getRequest();
        // 2.获取token
        String token = getToken(request);
        ServerHttpResponse response = exchange.getResponse();
        if (StringUtils.isBlank(token)) {
            // 3.token为空 返回401
            response.setStatusCode(HttpStatus.UNAUTHORIZED);
            return response.setComplete();
        }
        // 4.验证token是否有效
        String userId = getUserIdByToken(token);
        if (StringUtils.isBlank(userId)) {
            // 5.token无效 返回401
            response.setStatusCode(HttpStatus.UNAUTHORIZED);
            return response.setComplete();
        }
        // token有效，后续业务处理
        // 从写请求头，方便业务系统从请求头获取用户id进行权限相关处理
        ServerHttpRequest.Builder builder = exchange.getRequest().mutate();
        request = builder.header("user_id", userId).build();
        // 延长缓存过期时间-token缓存用户如果一直在操作就会一直重置过期
        // 这样避免用户操作过程中突然过期影响业务操作及体验，只有用户操作间隔时间大于缓存过期时间才会过期
        resetTokenExpirationTime(token, userId);
        // 完成验证
        return chain.filter(exchange);
    }
    @Override
    public int getOrder() {
        // 优先级 越小越优先
        return 0;
    }
    /**
     * 从redis中获取用户id
     * 在登录操作时候 登陆成功会生成一个token, redis得key为auth_token:token 值为用户id
     *
     * @param token
     * @return
     */
    private String getUserIdByToken(String token) {
        String redisKey = String.join(":", "auth_token", token);
        return redisTemplate.opsForValue().get(redisKey);
    }
    /**
     * 重置token过期时间
     *
     * @param token
     * @param userId
     */
    private void resetTokenExpirationTime(String token, String userId) {
        String redisKey = String.join(":", "auth_token", token);
        redisTemplate.opsForValue().set(redisKey, userId, 2, TimeUnit.HOURS);
    }
    /**
     * 获取token
     *
     * @param request
     * @return
     */
    private static String getToken(ServerHttpRequest request) {
        HttpHeaders headers = request.getHeaders();
        // 从请求头获取token
        String token = headers.getFirst(TOKEN_HEADER_KEY);
        if (StringUtils.isBlank(token)) {
            // 请求头无token则从url获取token
            token = request.getQueryParams().getFirst(TOKEN_HEADER_KEY);
        }
        if (StringUtils.isBlank(token)) {
            // 请求头和url都没有token则从cookies获取
            HttpCookie cookie = request.getCookies().getFirst(TOKEN_HEADER_KEY);
            if (cookie != null) {
                token = cookie.getValue();
            }
        }
        return token;
    }
}