最近接了一个新的需求，需要做一个网关的服务，在这期间遇到了跨域的问题，下面是借鉴的别人的方案，但是中间遇到了些别的问题，记录一下
下面是解决方案：

@Configuration
public class CorsConfig {
    private static final String MAX_AGE = "18000L";

    @Bean
    public WebFilter corsFilter() {
        return (ServerWebExchange ctx, WebFilterChain chain) -> {
            ServerHttpRequest request = ctx.getRequest();
            if (CorsUtils.isCorsRequest(request)) {
                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, "*");
                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);
        };
    }

    @Bean
    public ServerCodecConfigurer serverCodecConfigurer() {
        return new DefaultServerCodecConfigurer();
    }

    @Bean
    public RouteDefinitionLocator discoveryClientRouteDefinitionLocator(ReactiveDiscoveryClient discoveryClient,
                                                                        DiscoveryLocatorProperties properties) {
        return new DiscoveryClientRouteDefinitionLocator(discoveryClient, properties);
    }

文章出处：https://cloud.tencent.com/developer/article/1384110

我在这基础上做了一点小改动 ReactiveDiscoveryClient 这是类是我替换掉的 文章中的不建议使用了
再启动服务的时候又出现了一个小小的问题
ServerCodecConfigurer 这个configurer 已经被注册了
这里我们只需要添加下面的配置，允许覆盖默认的就可以了

spring:
  main:
    allow-bean-definition-overriding: true