<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-gateway</artifactId>
  <version>3.1.4</version>
</dependency>
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-loadbalancer</artifactId>
  <version>3.1.4</version>
</dependency>

public class GrayRoundRobinLoadBalancer implements ReactorServiceInstanceLoadBalancer {


  private static final Log log = LogFactory.getLog(RoundRobinLoadBalancer.class);


  final AtomicInteger position;


  final String serviceId;


  ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;


  public GrayRoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider,
      String serviceId) {
    this(serviceInstanceListSupplierProvider, serviceId, new Random().nextInt(1000));
  }


  public GrayRoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider,
      String serviceId, int seedPosition) {
    this.serviceId = serviceId;
    this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;
    this.position = new AtomicInteger(seedPosition);
  }


  @SuppressWarnings("rawtypes")
  @Override
  public Mono<Response<ServiceInstance>> choose(Request request) {
    ServiceInstanceListSupplier supplier = serviceInstanceListSupplierProvider
        .getIfAvailable(NoopServiceInstanceListSupplier::new);
    return supplier.get(request).next()
        .map(serviceInstances -> processInstanceResponse(supplier, serviceInstances, request));
  }


  @SuppressWarnings("rawtypes")
  private Response<ServiceInstance> processInstanceResponse(ServiceInstanceListSupplier supplier,
      List<ServiceInstance> serviceInstances, Request request) {
    Response<ServiceInstance> serviceInstanceResponse = getInstanceResponse(serviceInstances, request);
    if (supplier instanceof SelectedInstanceCallback && serviceInstanceResponse.hasServer()) {
      ((SelectedInstanceCallback) supplier).selectedServiceInstance(serviceInstanceResponse.getServer());
    }
    return serviceInstanceResponse;
  }


  @SuppressWarnings("rawtypes")
  private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances, Request request) {
    if (instances.isEmpty()) {
      if (log.isWarnEnabled()) {
        log.warn("No servers available for service: " + serviceId);
      }
      return new EmptyResponse();
    }
    List<ServiceInstance> result = instances.stream().filter(instance -> {
      Map<String, String> metadata = instance.getMetadata();
      Object orgId = metadata.get("v");
      RequestDataContext context = (RequestDataContext) request.getContext() ;
      RequestData requestData = context.getClientRequest() ;
      String v = null ;
      if (requestData instanceof GrayRequestData) {
        GrayRequestData grayRequestData = (GrayRequestData) requestData ;
        queryV = grayRequestData.getQueryParams().getFirst("v") ;
      }
      String value = requestData.getHeaders().getFirst("v") ;
      return v != null && (v.equals(value) || v.equals(queryV)) ;
    }).collect(Collectors.toList());
    if (result.isEmpty()) {
      result = instances;
    }
    int pos = this.position.incrementAndGet() & Integer.MAX_VALUE;


    ServiceInstance instance = result.get(pos % result.size());


    return new DefaultResponse(instance);
  }


}

@SuppressWarnings({ "rawtypes", "unchecked" })
@Component
public class GrayReactiveLoadBalancerClientFilter implements GlobalFilter, Ordered {


  private static final Log log = LogFactory.getLog(GrayReactiveLoadBalancerClientFilter.class);
  
  /**
   * Order of filter.
   */
  public static final int LOAD_BALANCER_CLIENT_FILTER_ORDER = 10150;


  private final LoadBalancerClientFactory clientFactory;


  private final GatewayLoadBalancerProperties properties;




  public GrayReactiveLoadBalancerClientFilter(LoadBalancerClientFactory clientFactory,
      GatewayLoadBalancerProperties properties) {
    this.clientFactory = clientFactory;
    this.properties = properties;
  }


  @Override
  public int getOrder() {
    return LOAD_BALANCER_CLIENT_FILTER_ORDER;
  }


  @Override
  public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    URI url = exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR);
    String schemePrefix = exchange.getAttribute(GATEWAY_SCHEME_PREFIX_ATTR);
    if (url == null || (!"packlb".equals(url.getScheme()) && !"packlb".equals(schemePrefix))) {
      return chain.filter(exchange);
    }
    // preserve the original url
    addOriginalRequestUrl(exchange, url);


    URI requestUri = exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR);
    String serviceId = requestUri.getHost();
    Set<LoadBalancerLifecycle> supportedLifecycleProcessors = LoadBalancerLifecycleValidator
        .getSupportedLifecycleProcessors(clientFactory.getInstances(serviceId, LoadBalancerLifecycle.class),
            RequestDataContext.class, ResponseData.class, ServiceInstance.class);
    DefaultRequest<RequestDataContext> lbRequest = new DefaultRequest<>(
        new RequestDataContext(new GrayRequestData(exchange.getRequest()), getHint(serviceId)));
    LoadBalancerProperties loadBalancerProperties = clientFactory.getProperties(serviceId);
    return choose(lbRequest, serviceId, supportedLifecycleProcessors).doOnNext(response -> {


      if (!response.hasServer()) {
        supportedLifecycleProcessors.forEach(lifecycle -> lifecycle
            .onComplete(new CompletionContext<>(CompletionContext.Status.DISCARD, lbRequest, response)));
        throw NotFoundException.create(properties.isUse404(), "Unable to find instance for " + url.getHost());
      }


      ServiceInstance retrievedInstance = response.getServer();


      URI uri = exchange.getRequest().getURI();


      // if the `lb:<scheme>` mechanism was used, use `<scheme>` as the default,
      // if the loadbalancer doesn't provide one.
      String overrideScheme = retrievedInstance.isSecure() ? "https" : "http";
      if (schemePrefix != null) {
        overrideScheme = url.getScheme();
      }


      DelegatingServiceInstance serviceInstance = new DelegatingServiceInstance(retrievedInstance,
          overrideScheme);


      URI requestUrl = reconstructURI(serviceInstance, uri);


      if (log.isTraceEnabled()) {
        log.trace("LoadBalancerClientFilter url chosen: " + requestUrl);
      }
      exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, requestUrl);
      exchange.getAttributes().put(GATEWAY_LOADBALANCER_RESPONSE_ATTR, response);
      supportedLifecycleProcessors.forEach(lifecycle -> lifecycle.onStartRequest(lbRequest, response));
    }).then(chain.filter(exchange))
        .doOnError(throwable -> supportedLifecycleProcessors.forEach(lifecycle -> lifecycle
            .onComplete(new CompletionContext<ResponseData, ServiceInstance, RequestDataContext>(
                CompletionContext.Status.FAILED, throwable, lbRequest,
                exchange.getAttribute(GATEWAY_LOADBALANCER_RESPONSE_ATTR)))))
        .doOnSuccess(aVoid -> supportedLifecycleProcessors.forEach(lifecycle -> lifecycle
            .onComplete(new CompletionContext<ResponseData, ServiceInstance, RequestDataContext>(
                CompletionContext.Status.SUCCESS, lbRequest,
                exchange.getAttribute(GATEWAY_LOADBALANCER_RESPONSE_ATTR), buildResponseData(exchange,
                    loadBalancerProperties.isUseRawStatusCodeInResponseData())))));
  }


  @SuppressWarnings("deprecation")
  private ResponseData buildResponseData(ServerWebExchange exchange, boolean useRawStatusCodes) {
    if (useRawStatusCodes) {
      return new ResponseData(new GrayRequestData(exchange.getRequest()), exchange.getResponse());
    }
    return new ResponseData(exchange.getResponse(), new RequestData(exchange.getRequest()));
  }


  protected URI reconstructURI(ServiceInstance serviceInstance, URI original) {
    return LoadBalancerUriTools.reconstructURI(serviceInstance, original);
  }


  private Mono<Response<ServiceInstance>> choose(Request<RequestDataContext> lbRequest, String serviceId,
      Set<LoadBalancerLifecycle> supportedLifecycleProcessors) {
    ReactorLoadBalancer<ServiceInstance> loadBalancer = this.clientFactory.getInstance(serviceId,
        ReactorServiceInstanceLoadBalancer.class);
    if (loadBalancer == null) {
      throw new NotFoundException("No loadbalancer available for " + serviceId);
    }
    supportedLifecycleProcessors.forEach(lifecycle -> lifecycle.onStart(lbRequest));
    return loadBalancer.choose(lbRequest);
  }


  private String getHint(String serviceId) {
    LoadBalancerProperties loadBalancerProperties = clientFactory.getProperties(serviceId);
    Map<String, String> hints = loadBalancerProperties.getHint();
    String defaultHint = hints.getOrDefault("default", "default");
    String hintPropertyValue = hints.get(serviceId);
    return hintPropertyValue != null ? hintPropertyValue : defaultHint;
  }


}

@Configuration
public class GrayDefaultConfiguration {


  @Bean
  public GrayRoundRobinLoadBalancer grayRandomLoadBalancer(Environment environment, LoadBalancerClientFactory loadBalancerClientFactory) {
    String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
    return new GrayRoundRobinLoadBalancer(
        loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), name);
  }
  
  // 由于沒(méi)有使用服務(wù)注冊(cè)及發(fā)現(xiàn)，這里通過(guò)編碼的方式定義服務(wù)實(shí)例
  @Bean
  public ServiceInstanceListSupplier sscServiceInstanceListSupplier() {
    return new ServiceInstanceListSupplier() {
      @Override
      public Flux<List<ServiceInstance>> get() {
        List<ServiceInstance> instances = new ArrayList<>() ;
        Map<String, String> metadata1 = new HashMap<>() ;
        metadata1.put("v", "1") ;
        ServiceInstance s1 = new DefaultServiceInstance("s1", "ssc", "localhost", 8088 , false, metadata1) ;
        instances.add(s1) ;
        
        Map<String, String> metadata2 = new HashMap<>() ;
        metadata2.put("v", "2") ;
        ServiceInstance s2 = new DefaultServiceInstance("s2", "ssc", "localhost", 8099 , false, metadata2) ;
        instances.add(s2) ;
        
        return Flux.just(instances) ;
      }
      @Override
      public String getServiceId() {
        return "ssc" ;
      }
    };
  }
  
}

@LoadBalancerClients(defaultConfiguration = GrayDefaultConfiguration.class)
public class SpringCloudGatewayApplication {
}