自定義Ribbon負載均衡規則

方法一

總的來說一句話：繼承IRule的實現類AbstractLoadBalancerRule ，實現後註冊到bean

package com.springcloud;

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.Random;

/**
 * Created by Choisaaaa on 2018/7/9.
 * 自定義隨機算法
 *
 * 一個服務實例server 用3次  在輪詢選擇下一個server
 */
public class MyRandomRule extends AbstractLoadBalancerRule {


    Random rand;

    public MyRandomRule() {
        rand = new Random();
    }

    /**
     * Randomly choose from all living servers
     */
    public Server choose(ILoadBalancer lb, Object key) {
    //重寫該方法
    }

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

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

    }
}

 這裏需要注意不能與啓動類同一級或其子級包下，否則將不起作用

package com.mark.config;

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

/**
 * Created by Choisaaaa on 2018/7/9.
 * 自定義的輪詢算法的配置類
 */
@Configuration
public class MyRuleConfig {

    @Bean //注入自定義的負載均衡的算法
    public IRule iRule(){
        return new MyRandomRule();
    }
}

啓動類加註釋 PROVIDERPRODUCT：要訪問的服務，MyRuleConfig：自定義規則類；即指定服務遵循自定義規則類

@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
//爲服務PROVIDERPRODUCT指定自定義的負載均衡算法
@RibbonClient(name = "PROVIDERPRODUCT",configuration = MyRuleConfig.class)
public class ConsumerApplication {

代碼參見：https://blog.csdn.net/ycd500756/article/details/80975410

方法二

1. 刪除config中RestTemplate的Ribbon默認負載均衡註釋@LoadBalanced

package com.atguigu.order.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;

@Configuration
public class ApplicationContextConfig
{
    @Bean
// 刪除Ribbon默認負載均衡的註釋
//    @LoadBalanced
    public RestTemplate getRestTemplate()
    {
        return new RestTemplate();
    }
}

2. 自定義接口及方法返回 ServiceInstance 

package com.atguigu.order.lb;

import org.springframework.cloud.client.ServiceInstance;

import java.util.List;

public interface LoadBalancer
{
// 仿照IRule的實現類,返回對象
    ServiceInstance instances(List<ServiceInstance> serviceInstances);
}

3. 實現該接口

package com.atguigu.order.lb;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

@Component
public class MyLB implements LoadBalancer
{

    private AtomicInteger atomicInteger = new AtomicInteger(0);

// 這裏模仿輪訓算法
    public final int getAndIncrement()
    {
        int current;
        int next;

        do {
            current = this.atomicInteger.get();
            next = current >= 2147483647 ? 0 : current + 1;
        }while(!this.atomicInteger.compareAndSet(current,next));
        System.out.println("*****第幾次訪問，次數next: "+next);
        return next;
    }

    //負載均衡算法：rest接口第幾次請求數 % 服務器集羣總數量 = 實際調用服務器位置下標  ，每次服務重啓動後rest接口計數從1開始。
    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances)
    {
        int index = getAndIncrement() % serviceInstances.size();

        return serviceInstances.get(index);
    }
}

4. contrller測試接口

    @Resource
    private LoadBalancer loadBalancer;
    @Resource
    private DiscoveryClient discoveryClient;

    @GetMapping(value = "/consumer/payment/lb")
    public String getPaymentLB()
    {
// 獲取服務對象集合信息(需要訪問的項目在eureka中的信息)
        List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");

        if(instances == null || instances.size() <= 0)
        {
            return null;
        }

        ServiceInstance serviceInstance = loadBalancer.instances(instances);
        URI uri = serviceInstance.getUri();

        return restTemplate.getForObject(uri+"/payment/lb",String.class);

    }