Spring Cloud Gateway Cors跨域问题的解决

CORS

前后端分离就会碰到跨域问题，原本我们在后端采用 CORS 解决，现在利用网关，可以放在网关解决。

版本：
spring-cloud：Hoxton.SR9
spring-cloud-gateway：2.3.2.RELEASE

一共两个文件

CorsConfiguration.java

/**
 * 配置跨域
 */
@Configuration
public class CorsConfiguration {

    @Bean
    public CorsResponseHeaderFilter corsResponseHeaderFilter() {
        return new CorsResponseHeaderFilter();
    }

    @Bean
    public CorsWebFilter corsWebFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        CorsConfiguration corsConfiguration = new CorsConfiguration();

        corsConfiguration.addAllowedHeader("*");
        corsConfiguration.addAllowedMethod("*");
        corsConfiguration.addAllowedOrigin("*");
        corsConfiguration.setAllowCredentials(true);
        corsConfiguration.setMaxAge(600L);

        source.registerCorsConfiguration("/**", corsConfiguration);
        return new CorsWebFilter(source);
    }
}

CorsResponseHeaderFilter.java

/**
 * 跨域请求头重复处理过滤器
 */
public class CorsResponseHeaderFilter implements GlobalFilter, Ordered {
    @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;
    }

    @Override
    @SuppressWarnings("serial")
    public Mono<Void> 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<String>() {
   {
                            add(kv.getValue().get(0));
                        }});
                    });

            return chain.filter(exchange);
        }));
    }
}

Springboot升级至2.4.0中出现的跨域问题。

ERROR 7576 --- [ctor-http-nio-5] a.w.r.e.AbstractErrorWebExceptionHandler : [28bc5558-2]  500 Server Error for HTTP OPTIONS "/api/login"

java.lang.IllegalArgumentException: When allowCredentials is true, allowedOrigins cannot contain the special value "*"since that cannot be set on the "Access-Control-Allow-Origin" response header. To allow credentials to a set of origins, list them explicitly or consider using "allowedOriginPatterns" instead.
	at org.springframework.web.cors.CorsConfiguration.validateAllowCredentials(CorsConfiguration.java:457) ~[spring-web-5.3.1.jar:5.3.1]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]

很明显还是跨域

When allowCredentials is true, allowedOrigins cannot contain the special value "*"since that cannot be set on the "Access-Control-Allow-Origin" response header. To allow credentials to a set of origins, list them explicitly or consider using "allowedOriginPatterns" instead.

意思就是不能在 configuration.setAllowCredentials(true)的时候对addAllowedOrigin设置为"*"，而要使用 allowedOriginPatterns这个字段来设置origin。

对于spring boot 2.4.0出现的跨域异常问题，直接给出解决方案。
 

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.cors.reactive.CorsWebFilter;
import org.springframework.web.cors.reactive.UrlBasedCorsConfigurationSource;
import org.springframework.web.util.pattern.PathPatternParser;

import java.util.ArrayList;
import java.util.List;

/**

 * @Description: 跨域问题
 */
@Configuration
public class CorsConfig {
    @Bean
    public CorsWebFilter corsWebFilter() {
        UrlBasedCorsConfigurationSource configurationSource = new UrlBasedCorsConfigurationSource(new PathPatternParser());
        CorsConfiguration configuration = new CorsConfiguration();
//       配置跨域
        configuration.setAllowCredentials(true);
        List<String> allowedOriginPatterns = new ArrayList<>();
        allowedOriginPatterns.add(CorsConfiguration.ALL);
        configuration.setAllowedOriginPatterns(allowedOriginPatterns);

        configuration.addAllowedHeader(CorsConfiguration.ALL);
        configuration.addAllowedMethod(CorsConfiguration.ALL);

        configurationSource.registerCorsConfiguration("/**", configuration);
        return new CorsWebFilter(configurationSource);
    }
}

使用 configuration.setAllowedOriginPatterns(allowedOriginPatterns) 就可以解决问题。