七、负载均衡-Ribbon 如何对负载均衡策略进行扩展

当内置的负载均衡策略不满足业务需求的时候，我们就需要自定义 Ribbon 的负载策略。
一、 继承 AbstractLoadBalancerRule 类

package com.comsys.configuration;

import java.util.List;

import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.ILoadBalancer;
import com.netflix.loadbalancer.Server;

public class RoncooCustomRule extends AbstractLoadBalancerRule {
    private Server choose(ILoadBalancer lb, Object key) { 
        if (lb == null) {
            return null; 
        } 
        Server server = null; 

        while (server == null) { 
            if (Thread.interrupted()) { 
                return null; 
            } 

            List upList = lb.getReachableServers(); // 可用的服务实例 

            // 只获取端口为：7779 的服务实例 
            for (Server s : upList) { 
                if (s.getPort() == 7777) { 
                    server = s; 
                } 
            } 

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

            System.out.println("实例 IP：" + server.getHost() + " 端口：" + 
            server.getPort()); 

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

            server = null; 
            Thread.yield(); 
        } 

        return server; 
    }

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

    @Override
    public void initWithNiwsConfig(IClientConfig arg0) {
    }

}

二、 配置策略

# 通过配置文件 
spring-cloud-provider.ribbon.NFLoadBalancerRuleClassName=com.roncoo.education.configuration.RoncooCustomRule