使用guava的一致性哈希算法

     <dependency>
          <groupId>com.google.guava</groupId>
          <artifactId>guava</artifactId>
          <version>23.0</version>
      </dependency>

然后自己写一个类，继承AbstractLoadBalancerRule：

package com.yy.item.controller;

import com.google.common.hash.Hashing;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.Server;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;
import java.util.List;
import java.util.Objects;

public class ConsistentHashRule extends AbstractLoadBalancerRule implements IRule {
    private Logger log = LoggerFactory.getLogger(ConsistentHashRule.class);

    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {

    }

    @Override
    public Server choose(Object key) {
        return choose(getLoadBalancer());
    }

    private Server choose(ILoadBalancer lb) {
        if (lb == null) {
            log.warn("no load balancer");
            return null;
        }

        Server server = null;
        int count = 0;
        while (count++ < 10) {
            List<Server> reachableServers = lb.getReachableServers();
            List<Server> allServers = lb.getAllServers();
            int upCount = reachableServers.size();
            int serverCount = allServers.size();
            if ((upCount == 0) || (serverCount == 0)) {
                log.warn("No up servers available from load balancer: " + lb);
                return null;
            }
            //获取请求URI
            HttpServletRequest request = ((ServletRequestAttributes) Objects.requireNonNull(RequestContextHolder.getRequestAttributes())).getRequest();
            String uri = request.getServletPath() + "?" + request.getQueryString();

            int hashcode = uri.hashCode();
            //一致性哈希，直接返回第几个数
            int model = Hashing.consistentHash(hashcode, serverCount);

            server = allServers.get(model);

            if (server == null) {
                Thread.yield();
                continue;
            }

            if (server.isAlive() && (server.isReadyToServe())) {
                return (server);
            }

            server = null;
        }

        if (count >= 10) {
            log.warn("No available alive servers after 10 tries from load balancer: "
                    + lb);
        }
        return server;


    }
}