代码如下

@Configurationpublic class CorsConfig implements GlobalFilter, Ordered {  private static final String ALL = "*";  private static final String MAX_AGE = "18000L";  @Bean  public RouteDefinitionLocator discoveryClientRouteDefinitionLocator(DiscoveryClient discoveryClient,                                    DiscoveryLocatorProperties properties) {    return new DiscoveryClientRouteDefinitionLocator(discoveryClient, properties);  }  @Bean  public ServerCodecConfigurer serverCodecConfigurer() {    return new DefaultServerCodecConfigurer();  }　　　//添加请求头　  @Bean  public WebFilter corsFilter() {    return (ServerWebExchange ctx, WebFilterChain chain) -> {      ServerHttpRequest request = ctx.getRequest();      if (!CorsUtils.isCorsRequest(request)) {        return chain.filter(ctx);      }      HttpHeaders requestHeaders = request.getHeaders();      ServerHttpResponse response = ctx.getResponse();      HttpMethod requestMethod = requestHeaders.getAccessControlRequestMethod();      HttpHeaders headers = response.getHeaders();      headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, requestHeaders.getOrigin());      headers.addAll(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS, requestHeaders.getAccessControlRequestHeaders());      if (requestMethod != null) {        headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, requestMethod.name());      }      headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS, "true");      headers.add(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS, ALL);      headers.add(HttpHeaders.ACCESS_CONTROL_MAX_AGE, MAX_AGE);      if (request.getMethod() == HttpMethod.OPTIONS) {        response.setStatusCode(HttpStatus.OK);        return Mono.empty();      }      return chain.filter(ctx);    };  }　　//将请求头中有多个值的去掉 这是该版本的一个bug  @Override  public Mono filter(ServerWebExchange exchange, GatewayFilterChain chain) {    return chain.filter(exchange).then(Mono.defer(() -> {      exchange.getResponse().getHeaders().entrySet().stream()          .filter(kv -> (kv.getValue() != null && kv.getValue().size() > 1))          .filter(kv -> (kv.getKey().equals(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN)              || kv.getKey().equals(HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS)))          .forEach(kv -> {            kv.setValue(new ArrayList() {{              add(kv.getValue().get(0));            }});          });      return chain.filter(exchange);    }));  }  @Override  public int getOrder() {    // 指定此过滤器位于NettyWriteResponseFilter之后    // 即待处理完响应体后接着处理响应头    return NettyWriteResponseFilter.WRITE_RESPONSE_FILTER_ORDER + 1;  }}

此处的spring-cloud-gateway的版本是2.1.3.RELEASE