spring cloud gateway跨域全局CORS配置方式

在Spring 5 Webflux中，配置CORS，可以通过自定义WebFilter实现：

注：此种写法需真实跨域访问，监控header中才会带相应属性。

代码实现方式

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.cors.reactive.CorsUtils;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import org.springframework.http.HttpMethod;
import reactor.core.publisher.Mono;
 
import static org.springframework.web.cors.CorsConfiguration.ALL;
public class XXXApplication{
public static void main(String[] args) {
    SpringApplication.run(XXXApplication.class, args);
}
private static final String MAX_AGE = "18000L";
@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);
    };
}
}

配置实现方式

网上还提到一种配置写法，实测好用：

spring:
  cloud:
    gateway:
      globalcors:
        corsConfigurations:
          '[/**]':
            allowedOrigins: "*"
            allowedMethods: "*"
            allowedHeaders: "*"

springcloud gateway 跨域的解决

springcloud gateway提供的自带的跨域过滤器有问题，前端还是会报跨域。zuul不会有这个问题。调试发现主要是游览器发送嗅探请求（OPTIONS）时，没有返回跨域的响应头，从而游览器报跨域问题。

验证

由于springcloud gateway为webflux与zuul不一样，同一个服务，采用spring内置的跨域过滤器，zuul可以通过而gateway报错。具体配置如下：

1、gateway跨域配置

spring:
  cloud:
    gateway:
      globalcors:
        cors-configurations:
          '[/**]':
            # 允许携带认证信息
            # 允许跨域的源(网站域名/ip)，设置*为全部
            # 允许跨域请求里的head字段，设置*为全部
            # 允许跨域的method， 默认为GET和OPTIONS，设置*为全部
            # 跨域允许的有效期
            allow-credentials: true
            allowed-origins: '*'
            allowed-headers: Content-Type,Content-Length, Authorization, Accept,X-Requested-With
            allowed-methods: '*'
            exposed-headers: Content-Type,Content-Length, Authorization, Accept,X-Requested-With
            max-age: 3600

此配置无效，前端还是会报跨域问题，主要是前端发送OPTIONS请求时没有返回跨域信息

2、zuul网关或者其它微服务servlet

向容器中注入跨域过滤器

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.core.Ordered;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
import org.springframework.web.filter.CorsFilter;

/**
 * @author ZhouChuGang
 * @version 1.0
 * @project langangkj-commonm
 * @date 2020/5/4 12:24
 * @Description 跨域过滤器配置
 */
@Slf4j
@configuration
@ConditionalOnMissingBean(CorsFilter.class)
@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET)
public class CorsFilterConfiguration {

    public CorsFilterConfiguration() {
        log.info("==========注入跨域过滤器=============");
    }

    @Bean("corsFilter")
    public CorsFilter corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        CorsConfiguration config = new CorsConfiguration();
        // #允许向该服务器提交请求的URI，*表示全部允许
        config.addAllowedOrigin(CorsConfiguration.ALL);
        // 允许cookies跨域
        config.setAllowCredentials(true);
        // #允许访问的头信息,*表示全部
        config.addAllowedHeader(CorsConfiguration.ALL);
        // 允许提交请求的方法，*表示全部允许
        config.addAllowedMethod(CorsConfiguration.ALL);
        source.registerCorsConfiguration("/**", config);
        return new CorsFilter(source);
    }

    @Autowired
    @Qualifier("corsFilter")
    private CorsFilter corsFilter;

    /**
     * 配置跨域过滤器
     */
    @Bean
    public FilterRegistrationBean<CorsFilter> corsFilterRegistration() {
        FilterRegistrationBean<CorsFilter> registration = new FilterRegistrationBean<>();
        registration.setFilter(corsFilter);
        registration.addUrlPatterns("/*");
        registration.setName("corsFilter");
        registration.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return registration;
    }
}

此方案可以完美解决跨域问题。但是springcloud gateway 不是servlet 规范。

解决方案

1、gateway后面的微服务实现跨域

跨域由网关后面的服务实现。

2、实现一个过滤器，来做跨域允许

需要在响应头中加入以下信息

# 这个为请求头中的 origin
add_header 'Access-Control-Allow-Origin' '$http_origin' ;
add_header 'Access-Control-Allow-Credentials' 'true' ;
add_header 'Access-Control-Allow-Methods' 'PUT,POST,GET,DELETE,OPTIONS' ;
add_header 'Access-Control-Allow-Headers' 'Content-Type,Content-Length,Authorization,Accept,X-Requested-With' ;

3、采用nginx做代理，配置跨域响应头。（强烈推荐）

请求先到nginx，nginx再去请求gateway， 由nginx添加跨域响应头

add_header 'Access-Control-Allow-Origin' '$http_origin' ;
add_header 'Access-Control-Allow-Credentials' 'true' ;
add_header 'Access-Control-Allow-Methods' 'PUT,POST,GET,DELETE,OPTIONS' ;
add_header 'Access-Control-Allow-Headers' 'Content-Type,Content-Length,Authorization,Accept,X-Requested-With' ;

这里本人为了方便，采用第3中方案，测试完美解决！

以上为个人经验，希望能给大家一个参考，也希望大家多多支持。