曲线救国，解决spring-boot2.0.6中webflux无法获得请求IP的问题

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.reactive.function.server.ServerResponse;
import reactor.core.publisher.Mono;

import static org.springframework.web.reactive.function.server.RequestPredicates.GET;
import static org.springframework.web.reactive.function.server.RequestPredicates.accept;
import static org.springframework.web.reactive.function.server.RouterFunctions.route;

/**
 * 某业务 Handler
 */
@Component
public class SplashHandler {

    private Mono<ServerResponse> execute(ServerRequest serverRequest) {
        ... 业务代码
        // serverRequest 获得 IP ？
        ... 业务代码
    }

    @Configuration
    public static class RoutingConfiguration {

        @Bean
        public RouterFunction<ServerResponse> execute(SplashHandler handler) {
            return route(
                    GET("/api/ad").and(accept(MediaType.TEXT_HTML)),
                    handler::execute
            );
        }
    }
}

org.springframework.web.server.ServerWebExchange#getRequest
org.springframework.http.server.reactive.ServerHttpRequest#getRemoteAddress

import org.springframework.context.annotation.Configuration;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.web.reactive.config.CorsRegistry;
import org.springframework.web.reactive.config.WebFluxConfigurer;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;

import java.net.InetSocketAddress;
import java.util.Objects;

/*
If you want to keep Spring Boot WebFlux features and you want to add additional WebFlux configuration, you can add your own @Configuration class of type WebFluxConfigurer but without @EnableWebFlux.
If you want to take complete control of Spring WebFlux, you can add your own @Configuration annotated with @EnableWebFlux.
 */
@Configuration
public class WebConfiguration implements WebFluxConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry
                .addMapping("/**")
                .allowedOrigins("*")
                .allowedMethods("GET", "POST", "PUT", "PATCH", "DELETE", "OPTION")
                .allowedHeaders("header1", "header2", "header3")
                .exposedHeaders("header1", "header2")
                .allowCredentials(true)
                .maxAge(3600);
    }

    /**
     * https://stackoverflow.com/questions/51192630/how-do-you-get-clients-ip-address-spring-webflux-websocket?rq=1
     * https://stackoverflow.com/questions/50981136/how-to-get-client-ip-in-webflux
     * https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#webflux-filters
     * 由于在低版本的 spring-webflux 中不支持直接获得请求 IP（https://jira.spring.io/browse/SPR-16681），因此写了一个补丁曲线救国，
     * 从 org.springframework.web.server.ServerWebExchange 中获得 IP 后，在放到 header 里
     */
    @Component
    public static class RetrieveClientIpWebFilter implements WebFilter {

        @Override
        public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
            InetSocketAddress remoteAddress = exchange.getRequest().getRemoteAddress();
            String clientIp = Objects.requireNonNull(remoteAddress).getAddress().getHostAddress();
            ServerHttpRequest mutatedServerHttpRequest = exchange.getRequest().mutate().header("X-CLIENT-IP", clientIp).build();
            ServerWebExchange mutatedServerWebExchange = exchange.mutate().request(mutatedServerHttpRequest).build();
            return chain.filter(mutatedServerWebExchange);
        }
    }
}

private Mono<ServerResponse> execute(ServerRequest serverRequest) {
    String clientIp = serverRequest.headers().asHttpHeaders().getFirst("X-CLIENT-IP")
    ... 业务代码
}