spring cloud gateway自定义负载均衡, 优先转发到指定IP

在Spring Cloud Gateway中，你可以通过定义自定义的LoadBalancer来实现这一需求。以下是一个简单的例子，展示如何创建一个自定义的LoadBalancer，它会优先转发请求到指定的IP地址。

首先，你需要实现ReactiveLoadBalancer接口：

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.ReactiveLoadBalancer;
import org.springframework.http.HttpHeaders;
import org.springframework.web.reactive.function.client.WebClient;
import reactor.core.publisher.Mono;
 
import java.net.URI;
import java.util.List;
 
public class CustomLoadBalancer implements ReactiveLoadBalancer {
 
    private final WebClient webClient;
    private final String prefferedIp;
 
    public CustomLoadBalancer(WebClient.Builder webClientBuilder, String prefferedIp) {
        this.webClient = webClientBuilder.build();
        this.prefferedIp = prefferedIp;
    }
 
    @Override
    public Mono<Response<ServiceInstance>> choose(Request request) {
        // 创建一个虚拟的ServiceInstance，使用指定的IP
        ServiceInstance serviceInstance = new ServiceInstance() {
            @Override
            public String getInstanceId() {
                return prefferedIp;
            }
 
            @Override
            public String getHost() {
                return prefferedIp;
            }
 
            @Override
            public int getPort() {
                // 你的端口号
                return 80;
            }
 
            @Override
            public boolean isSecure() {
                return false;
            }
 
            @Override
            public URI getUri() {
                return URI.create("http://" + prefferedIp);
            }
 
            @Override
            public Map<String, String> getMetadata() {
                return null;
            }
 
            @Override
            public String getServiceId() {
                return request.getServiceId();
            }
        };
 
        return Mono.just(new DefaultResponse(serviceInstance));
    }
 
    @Override
    public Mono<Void> execute(ServiceInstance serviceInstance, Request<ByteBuffer> request, byte[] bytes) {
        URI uri = serviceInstance.getUri();
        HttpHeaders headers = new HttpHeaders();
        // 设置请求头信息
        // ...
        return webClient.post()
                .uri(uri)
                .headers(httpHeaders -> httpH