微服务Ribbon（四）

算法

由于Ribbon是客户端的负载均衡，那么我们就先提供几个客户端的服务提供者。8002,8003，现在有一个8001,建立新的module
复制粘贴pom引用，及所有8001有的类和源,修改yml文件(主要是端口，数据库名及别名，注意不能修改原始服务名字)及启动类
数据库使用上一个脚本修改创建。
然后建立如下工程(消费者)

pom.xml 注意Ribbon的引用建立在eureka上，因为要负载均衡肯定要和服务端打交道，所以这是客户端的eureka

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>cloud2018</artifactId>
        <groupId>com.tzy.spring</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>cloud-consumer-dept-80</artifactId>
    <description>部门微服务消费者</description>

    <dependencies>
        <dependency><!-- 自己定义的api -->
            <artifactId>cloud-api</artifactId>
            <groupId>com.tzy.spring</groupId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <!-- Ribbon相关 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-ribbon</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- 修改后立即生效，热部署 -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>springloaded</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
    </dependencies>

</project>

>yml文件

server:
  port: 80
       
eureka:
  client:
    register-with-eureka: false    #取消注册自己
    service-url: 
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/  

>启动类

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;

@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name="CLOUD-DEPT")
public class DeptConsumer80_App
{
	public static void main(String[] args)
	{
		SpringApplication.run(DeptConsumer80_App.class, args);
	}
}

>configBean.java 里面我们加入了RestTemplate，这个是spring提供的Resful风格的调用模板类

import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RetryRule;
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 ConfigBean //boot -->spring   applicationContext.xml --- @Configuration配置   ConfigBean = applicationContext.xml
{ 
	@Bean
	@LoadBalanced//Spring Cloud Ribbon是基于Netflix Ribbon实现的一套客户端       负载均衡的工具。
	public RestTemplate getRestTemplate()
	{
		return new RestTemplate();
	}
	//配置需要的算法，有7种，参考上面的算法介绍
	@Bean
	public IRule myRule()
	{
		//return new RoundRobinRule();
		//return new RandomRule();//达到的目的，用我们重新选择的随机算法替代默认的轮询。
		return new RetryRule();
	}
}

>DeptController_Consumer.java

import com.tzy.spring.entities.Dept;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.util.List;

@RestController
public class DeptController_Consumer
{

	//private static final String REST_URL_PREFIX = "http://localhost:8001";
	private static final String REST_URL_PREFIX = "http://CLOUD-DEPT";//微服务名字

	/**
	 * 使用 使用restTemplate访问restful接口非常的简单粗暴无脑。 (url, requestMap,
	 * ResponseBean.class)这三个参数分别代表 REST请求地址、请求参数、HTTP响应转换被转换成的对象类型。
	 */
	@Autowired
	private RestTemplate restTemplate;

	@RequestMapping(value = "/consumer/dept/add")
	public boolean add(Dept dept)
	{
		return restTemplate.postForObject(REST_URL_PREFIX + "/dept/add", dept, Boolean.class);
	}

	@RequestMapping(value = "/consumer/dept/get/{id}")
	public Dept get(@PathVariable("id") Long id)
	{
		return restTemplate.getForObject(REST_URL_PREFIX + "/dept/get/" + id, Dept.class);
	}

	@SuppressWarnings("unchecked")
	@RequestMapping(value = "/consumer/dept/list")
	public List<Dept> list()
	{
		return restTemplate.getForObject(REST_URL_PREFIX + "/dept/list", List.class);
	}

	// 测试@EnableDiscoveryClient,消费端可以调用服务发现
	@RequestMapping(value = "/consumer/dept/discovery")
	public Object discovery()
	{
		return restTemplate.getForObject(REST_URL_PREFIX + "/dept/discovery", Object.class);
	}

}

>挨个启动试试效果吧 http://localhost/consumer/dept/list 刷新效果很明显看出负载均衡了。  

---

来个自定义的Ribbon自定义的算法

也就是不能和主启动类所在的包及其子包下。 要不然所有Ribbon客户端都会共享，就起不到特殊定制的功效了。
新建MySelfRule.java

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

@Configuration
public class MySelfRule
{
	@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 RandomRule_ZY();// 我自定义为每台机器5次
	}
}

>主启动类添加注解

import com.tzy.spring.myrule.MySelfRule;
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;

@SpringBootApplication
@EnableEurekaClient
//在启动该微服务的时候就能去加载我们的自定义Ribbon配置类，从而使配置生效
@RibbonClient(name="CLOUD-DEPT",configuration=MySelfRule.class)
public class DeptConsumer80_App
{
	public static void main(String[] args)
	{
		SpringApplication.run(DeptConsumer80_App.class, args);
	}
}

>来了个自己的需求，每台机器5次的轮寻

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 RandomRule_ZY 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 Server choose(Object key) {
        return choose(getLoadBalancer(), key);
    }

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

    }

}

>可以玩玩了 >访问这个http://localhost/consumer/dept/list 五次一轮寻