现如今，互联网公司的架构基本上都是前后端分离的架构，当前端域名和后端暴露接口域名不完全一致时，前端就无法正常请求接口，这个时候，就需要后端支持跨域，而对跨域的支持，正常情况下都是在网关层面做支持，故在spring cloud gateway中支持跨域是很常见的场景。

方式一

spring:
  cloud:
    gateway:
      filter:
        remove-hop-by-hop:
          headers:
          # 以下是去掉网关默认去掉的请求响应头
          - trailer
          - te
          - keep-alive
          - transfer-encoding
          - upgrade
          - proxy-authenticate
          - connection
          - proxy-authorization
          - x-application-context
          # 以下是去掉服务层面定义的跨域
          - access-control-allow-credentials
          - access-control-allow-headers
          - access-control-allow-methods
          - access-control-allow-origin
          - access-control-max-age
          - vary
      globalcors:
        corsConfigurations:
          '[/**]':
            allowCredentials: true
            allowedOrigins: "*"
            allowedHeaders: "*"
            allowedMethods: "*"
            maxAge: 3628800

方式二 

@Bean
public WebFilter corsFilter() {
    return (exchange, chain) -> {
        ServerHttpRequest request = exchange.getRequest();
        if (!CorsUtils.isCorsRequest(request)) {
            return chain.filter(exchange);
        }
        ServerHttpResponse response = exchange.getResponse();
        HttpHeaders headers = response.getHeaders();
        headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, "*");
        headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, "POST,GET,OPTIONS,DELETE,PUT");
        headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS, "content-type");
        headers.add(HttpHeaders.ACCESS_CONTROL_MAX_AGE, "3628800");
        return chain.filter(exchange);
    };
}

方式三

@Configuration
public class CorsConfig {

    @Bean
    public CorsWebFilter corsFilter(){
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource(new PathPatternParser());
        source.registerCorsConfiguration("/**", buildConfig());
        return new CorsWebFilter(source);
    }

    private CorsConfiguration buildConfig(){
        CorsConfiguration corsConfiguration = new CorsConfiguration();

        corsConfiguration.addAllowedOrigin("*");
        corsConfiguration.addAllowedHeader("content-type");
        corsConfiguration.addAllowedMethod("POST,GET,OPTIONS,DELETE,PUT");
        corsConfiguration.setMaxAge(3628800L);

        return corsConfiguration;
    }
}