springcloud工程构建过程

1.概述

2.zookeeper与eureka在CAP理论中的区别

(电商时,应当保证高可用,即最好选用AP)

eureka遵守AP

zookeeper遵守CP

eureka集群,不区分主从节点

zookeeper集群,区分主从节点,主挂掉,其他进行选举

 3.负载均衡Ribbon(指的是consumer端)

3.1

3.2常用负载均衡算法有轮询,IP哈希,随机

3.3自定义ribbon类

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

/**
 * 自定义负载均衡算法1:
 * 不能与主启动类放在同一包下,即不能一起扫描
 * 此时主启动类需要添加注解:
 *      @RibbonClient(name="microservice-cloud-dept",configuration= CustomerIRule01.class)
 */
@Configuration
public class CustomerIRule01 {

    @Bean
    public IRule myRule(){
        //return new RandomRule();// Ribbon默认是轮询，我自定义为随机
        //return new RoundRobinRule();// Ribbon默认是轮询，我自定义为随机
        return new IRuleAlgo(); // 使用自定义的算法
    }
}

package com.zy.IRuleSelf;

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;

public class IRuleAlgo extends AbstractLoadBalancerRule {

    // total = 0 // 当total==5以后，我们指针才能往下走，
    // index = 0 // 当前对外提供服务的服务器地址，
    // total需要重新置为零，但是已经达到过一个5次，我们的index = 1
    // 分析：我们5次，但是微服务只有8001 8002 8003 三台，OK？
    //

    private int total = 0;             // 总共被调用的次数，目前要求每台被调用5次
    private int currentIndex = 0;    // 当前提供服务的机器号

    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;
            }

//            int index = rand.nextInt(serverCount);// java.util.Random().nextInt(3);
//            server = upList.get(index);

//            private int total = 0;             // 总共被调用的次数，目前要求每台被调用5次
//            private int currentIndex = 0;    // 当前提供服务的机器号
            if(total < 5)
            {
                server = upList.get(currentIndex);
                total++;
            }else {
                total = 0;
                currentIndex++;
                if(currentIndex >= upList.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;

    }

    @Override
    public void initWithNiwsConfig(IClientConfig iClientConfig) {

    }

    @Override
    public Server choose(Object o) {
        return null;
    }
}

3.4负载均衡的另一种方式(feign)

4.服务熔断(指的是provider端)

5.服务降级(降级是在consumer端,当然是先关闭provider端)

6.网关,路由