Ribbon

自定义Ribbon算法

自定义Ribbon 官网文档链接    Ribbon github源码地址

     <!--ribbon配置-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>

在主启动类上加上@RibbonClient

name表示server的名字，configuration表示自定义Ribbon算法的类

@RibbonClient(name = "COULD-DEPT-PROVIDE-DEPT", configuration = MyIrule.class)

package com.amber.springcloud;

import com.amber.MyIrule.MyIrule;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.ribbon.RibbonClient;

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@EnableEurekaClient
@RibbonClient(name = "COULD-DEPT-PROVIDE-DEPT", configuration = MyIrule.class)
public class ConsumerDept6001 {

    public static void main(String[] args){
        SpringApplication.run(ConsumerDept6001.class, args);
    }
}

package com.amber.MyIrule;

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

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

/**
 * A loadbalacing strategy that randomly distributes traffic amongst existing
 * servers.
 *
 * @author stonse
 *
 */
public class MyIrule extends AbstractLoadBalancerRule {
    int currentIndex = 0;
    int total = 0;
    /**
     * Randomly choose from all living servers
     */
    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();
            List<Server> allList = lb.getAllServers();

            int serverCount = allList.size();
            if (serverCount == 0) {
                /*
                 * No servers. End regardless of pass, because subsequent passes
                 * only get more restrictive.
                 */
                return null;
            }
              //获取当前可用的server
//            int index = chooseRandomInt(serverCount);
              //获取所有的server
//            server = upList.get(index);

            if (total < 3) {
                server = upList.get(currentIndex);
                total ++;
            } else {
                total = 0;
                currentIndex ++;
                if (currentIndex > allList.size()) {
                    currentIndex = 0;
                }
            }

            if (server == null) {
                /*
                 * The only time this should happen is if the server list were
                 * somehow trimmed. This is a transient condition. Retry after
                 * yielding.
                 */
                Thread.yield();
                continue;
            }

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

            // Shouldn't actually happen.. but must be transient or a bug.
            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

    }
}

RandomRule源码地址。修改里面的Choose方法，实现。把原来的每次随机调用，换成每台server调用3次。

Important

自定义Ribbon算法的时候，自定义类不能够方法哦@ComponentScan下。因此MyRule.java不能放在SpringBoot启动类的包以及子包下