Spring Cloud Loadbalancer 实现客户端负载均衡

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.reactive.function.client.WebClient;
 
public class LoadBalancedWebClient {
    private final WebClient.Builder webClientBuilder;
    private final LoadBalancerClient loadBalancer;
 
    public LoadBalancedWebClient(WebClient.Builder webClientBuilder, LoadBalancerClient loadBalancer) {
        this.webClientBuilder = webClientBuilder;
        this.loadBalancer = loadBalancer;
    }
 
    public WebClient createWebClient(String serviceId) {
        ServiceInstance instance = this.loadBalancer.choose(serviceId);
        String url = String.format("http://%s:%s", instance.getHost(), instance.getPort());
        return webClientBuilder.baseUrl(url).build();
    }
}

这段代码展示了如何使用Spring Cloud LoadBalancer客户端来选择一个服务实例，并构建一个WebClient以用于对该实例发起请求。LoadBalancerClient的choose方法根据提供的服务ID选择一个实例，然后将实例的主机和端口拼接成完整的URL，传递给WebClient.Builder来创建一个新的WebClient实例。这个实例之后可以用来发送HTTP请求到该服务。