Ribbon

Spring Cloud Ribbon是基于NetFlix Ribbon实现的客户端负载均衡工具

主要功能是提供客户端的软件负载均衡算法，将NetFlix的中间层服务连接在一起。在配置文件中列出LoadBalancer后面的所有机器，Ribbon会自动帮助你基于某些规则（轮询、随机数轮询、随机连接等）去连接这些服务。

自定义算法：

package com.sw.myrule;

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

import java.util.List;
import java.util.concurrent.ThreadLocalRandom;

/**
 * @Author suaxi
 * @Date 2020/12/29 16:44
 */
public class MyRandomRule extends AbstractLoadBalancerRule {

    //自定义算法：每个服务访问5次之后，换下一个
    private int total = 0; //被调用的次数
    private int currentIndex = 0; //当前是谁在提供服务

    public Server choose(ILoadBalancer lb, Object key) {
        if (lb == null) {
            return null;
        }
        Server server = null;

        while (server == null) {
            if (Thread.interrupted()) {
                return null;
            }
            List<Server> upList = lb.getReachableServers(); //获取活着的服务
            List<Server> allList = lb.getAllServers(); //获取所有服务

            int serverCount = allList.size();
            if (serverCount == 0) {
                return null;
            }

//            int index = chooseRandomInt(serverCount); //生成区间随机数
//            server = upList.get(index); //从活着的服务中，随机获取一个

            if (total<5){
                server = upList.get(currentIndex);
                total++;
            }else {
                total = 0;
                currentIndex++;
                if (currentIndex>upList.size()){
                    currentIndex = 0; //当提供服务的人的执行次数大于活着的服务数量时，重置为0
                }
                server = upList.get(currentIndex); //从或者的服务中来获取指定的服务
            }

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

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

            server = null;
            Thread.yield();
        }

        return server;

    }

    protected int chooseRandomInt(int serverCount) {
        return ThreadLocalRandom.current().nextInt(serverCount);
    }

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

    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {
        // TODO Auto-generated method stub

    }
}

注册到Spring容器中

package com.sw.myrule;

import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RoundRobinRule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @Author suaxi
 * @Date 2020/12/29 16:12
 */

@Configuration
public class TestRule {

    @Bean
    public IRule myRule(){
        return new MyRandomRule();
    }
}

package com.sw.springcloud.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

/**
 * @Author suaxi
 * @Date 2020/12/28 22:15
 */

@Configuration
public class ConfigBean {

    //配置负载均衡实现RestTemplate
    //IRule
    //RoundRobinRule 轮询
    //RandomRule 随机数
    //AvailabilityFilteringRule 先过滤不可用的服务，对剩下的进行轮询
    //RetryRule 先按照轮询获取服务，如果获取服务失败，则会在指定的时间内进行重试
    @Bean
    @LoadBalanced //注册Ribbon
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }
}

开启自定义Ribbon注解

package com.sw.springcloud;

import com.sw.myrule.TestRule;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.ribbon.RibbonClient;

/**
 * @Author suaxi
 * @Date 2020/12/28 22:29
 */

@SpringBootApplication
@EnableEurekaClient
//在微服务启动的时候加载自定义的Ribbon类
@RibbonClient(name = "SPRINGCLOUD-PROVIDER-DEPT",configuration = TestRule.class)
public class DeptConsumer_80 {
    public static void main(String[] args) {
        SpringApplication.run(DeptConsumer_80.class,args);
    }
}