SpringCloudGateway解决跨域

很久以前我写了一个关于使用springCloudGateway解决跨域的问题，https://www.jianshu.com/p/f1938b6fc44a
那个文章确实可以解决，但是新版本的springCloudGateway提供了跨域的配置，所以我们不需要自己编写跨域配置类就可以解决跨域了。官网解决跨域的地址如下：https://docs.spring.io/spring-cloud-gateway/docs/2.2.5.RELEASE/reference/html/#cors-configuration

我先写一个跨域解决的配置，然后分析一下哈

spring:
  cloud:
    gateway:
      globalcors:
        cors-configurations:
          '[/**]':
            allowedOrigins: "*"
            allowedMethods: "*"
            allowedHeaders: "*"
            allowCredentials: true

cros-configuration后面关联的是一个map结构，key是uri匹配的地址，value为具体的跨域对象配置。

@ConfigurationProperties("spring.cloud.gateway.globalcors")
public class GlobalCorsProperties {

    private final Map<String, CorsConfiguration> corsConfigurations = new LinkedHashMap<>();

    public Map<String, CorsConfiguration> getCorsConfigurations() {
        return corsConfigurations;
    }
}

springcloudgateway启动时会将跨域配置注入到SimpleUrlHandlerMapping中，所以，如果我们使用配置中心配置跨域，网关运行的时候更新跨域配置是无效的！！！

/**
 * This is useful for PreFlight CORS requests. We can add a "global" configuration here so
 * we don't have to modify existing predicates to allow the "options" HTTP method.
 *
 */

@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(SimpleUrlHandlerMapping.class)
@ConditionalOnProperty(
        name = "spring.cloud.gateway.globalcors.add-to-simple-url-handler-mapping",
        matchIfMissing = false)
public class SimpleUrlHandlerMappingGlobalCorsAutoConfiguration {

    @Autowired
    private GlobalCorsProperties globalCorsProperties;

    @Autowired
    private SimpleUrlHandlerMapping simpleUrlHandlerMapping;

    @PostConstruct
    void config() {
        simpleUrlHandlerMapping
                .setCorsConfigurations(globalCorsProperties.getCorsConfigurations());
    }

}