5、Spring Cloud Ribbon

1.Ribbon简介

(1).Ribbon介绍

Spring Cloud Ribbon是基于Netflix Ribbon实现的一套客户端负载均衡的工具。

Ribbon是Netflix发布的开源项目，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。Ribbon客户端组件提供一系列完善的配置项如连接超时，重试等。简单的说，就是在配置文件中列出Load Balancer（简称LB）后面所有的机器，Ribbon会自动的帮助你基于某种规则（如简单轮询，随机连接等）去连接这些机器。我们也很容易使用Ribbon实现自定义的负载均衡算法。

(2).Ribbon作用

Ribbon是基于Netflix Ribbon实现的一套客户端负载均衡(LB)的工具。

LB(负载均衡):集中式LB和进程内LB。

  集中式LB：即在服务的消费方和提供方之间使用独立的LB设施(可以是硬件，如F5, 也可以是软件，如nginx), 由该设施负责把访问请求通过某种策略转发至服务的提供方；

F5:https://baike.baidu.com/item/F5%E6%96%B9%E6%A1%88/1121377?fr=aladdin

进程内LB：将LB逻辑集成到消费方，消费方从服务注册中心获知有哪些地址可用，然后自己再从这些地址中选择出一个合适的服务器。

Ribbon就属于进程内LB，它只是一个类库，集成于消费方进程，消费方通过它来获取到服务提供方的地址。

官方文档：

https://github.com/Netflix/ribbon/wiki

https://github.com/Netflix/ribbon/wiki/Getting-Started

2.Ribbon配置

修改microservicecloud-consumer-dept-80工程

(1).修改pom.xml文件

修改部分：

<!-- 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>

</dependencies>

完整部分：

<?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>microservicecloud</artifactId>

<groupId>com.hosystem</groupId>

<version>1.0-SNAPSHOT</version>

</parent>

<modelVersion>4.0.0</modelVersion>

<artifactId>microservicecloud-consumer-dept-80</artifactId>

<!--<description>部门微服务消费者</description>-->

    <dependencies>

<dependency><!-- 自己定义的api -->

            <!--注意：groupId我们需要由com.hosystem.springcloud 变成com.hosystem就不会出现'Dependency 'com.hosystem.springcloud:microservicecloud-api:1.0-SNAPSHOT' not found'错误-->

            <groupId>com.hosystem</groupId>

<artifactId>microservicecloud-api</artifactId>

<version>${project.version}</version>

</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>

<!-- 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>

</dependencies>

</project>

(2).修改application.yml

追加eureka的服务注册地址。

修改部分：

eureka:

  client:

    register-with-eureka: false

    service-url:

      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/

完整部分：

server:

  port: 80

eureka:

  client:

    register-with-eureka: false

    service-url:

      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/

(3).修改ConfigBean.java

对ConfigBean进行新注解@LoadBalanced,获得Rest时加入Ribbon的配置;

package com.hosystem.springcloud.cfgbeans;

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();

}

}

//applicationContext.xml  ---> @Configuration public class ConfigBean {}

//<bean id=UserService" class="com.hosystem.tmall.UserServiceImple>

(4).修改DeptConsumer80_App.java

主启动类DeptConsumer80_App添加@EnableEurekaClient

package com.hosystem.springcloud;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication

@EnableEurekaClient

public class DeptConsumer80_App

{

public static void main(String[] args)

{

SpringApplication.run(DeptConsumer80_App.class, args);

}

}

(5).修改DeptController_Consumer.java

修改DeptController_Consumer客户端访问类

package com.hosystem.springcloud.controller;

import com.hosystem.springcloud.entities.Dept;

import java.util.List;

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;

@RestController //注:这里一定不能忘记注解@RestController 否则出现404;

public class DeptController_Consumer {

/**

     *  使用restTemplate访问restful接口非常的简单;

     *  (url, requestMap, ResponseBean.class)三个参数代表REST请求地址、请求参数、HTTP响应转换被转换成的对象类型

     */

//    private static final String REST_URL_PREFIX = "http://localhost:8001";

    //修改为微服务名 实现名字访问微服务

    private static final String REST_URL_PREFIX = "http://MICROSERVICECLOUD-DEPT";

@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"):压制警告，因为我们使用了过期的方法

    @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);

}

}

/**

 *  JDBC    Spring JDBCTemplate

 *          Spring RestTemplate

 */

(6).启动eureka、provider、consumer

先启动3个eureka7001、eureka7002、eureka7003集群后，再启动microservicecloud-provider-dept-8001并注册进eureka，最后启动microservicecloud-consumer-dept-80。

(7).测试

http://localhost/consumer/dept/get/1

http://localhost/consumer/dept/list

http://localhost/consumer/dept/add?dname=大数据部

(8).总结

Ribbon和Eureka整合后Consumer可以直接调用服务而不用再关心地址和端口号

3.Ribbon负载均衡

(1).Ribbon架构介绍

Ribbon在工作时分成两步：第一步先选择 EurekaServer ,它优先选择在同一个区域内负载较少的server.第二步再根据用户指定的策略，在从server取到的服务注册列表中选择一个地址。其中Ribbon提供了多种策略：比如轮询、随机和根据响应时间加权。

(2).创建provider8002、provider8003

[1].创建工程provider8002

[2].创建工程provider8003

(3).配置pom文件

[1].配置provider8002 pom文件

<?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>microservicecloud</artifactId>

<groupId>com.hosystem</groupId>

<version>1.0-SNAPSHOT</version>

</parent>

<modelVersion>4.0.0</modelVersion>

<artifactId>microservicecloud-provider-dept-8002</artifactId>

<dependencies>

<dependency><!-- 引入自己定义的api通用包，可以使用Dept部门Entity -->

            <groupId>com.hosystem</groupId>

<artifactId>microservicecloud-api</artifactId>

<version>${project.version}</version>

</dependency>

<dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

</dependency>

<dependency>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

</dependency>

<dependency>

<groupId>com.alibaba</groupId>

<artifactId>druid</artifactId>

</dependency>

<dependency>

<groupId>ch.qos.logback</groupId>

<artifactId>logback-core</artifactId>

</dependency>

<dependency>

<groupId>org.mybatis.spring.boot</groupId>

<artifactId>mybatis-spring-boot-starter</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-jetty</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</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>

<!-- 将微服务provider侧注册进eureka -->

        <dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-eureka</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-config</artifactId>

</dependency>

<!-- actuator监控信息完善 -->

        <dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-actuator</artifactId>

</dependency>

</dependencies>

</project>

[2].配置provider8003 pom文件

<?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>microservicecloud</artifactId>

<groupId>com.hosystem</groupId>

<version>1.0-SNAPSHOT</version>

</parent>

<modelVersion>4.0.0</modelVersion>

<artifactId>microservicecloud-provider-dept-8003</artifactId>

<dependencies>

<dependency><!-- 引入自己定义的api通用包，可以使用Dept部门Entity -->

            <groupId>com.hosystem</groupId>

<artifactId>microservicecloud-api</artifactId>

<version>${project.version}</version>

</dependency>

<dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

</dependency>

<dependency>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

</dependency>

<dependency>

<groupId>com.alibaba</groupId>

<artifactId>druid</artifactId>

</dependency>

<dependency>

<groupId>ch.qos.logback</groupId>

<artifactId>logback-core</artifactId>

</dependency>

<dependency>

<groupId>org.mybatis.spring.boot</groupId>

<artifactId>mybatis-spring-boot-starter</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-jetty</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</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>

<!-- 将微服务provider侧注册进eureka -->

        <dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-eureka</artifactId>

</dependency>

<dependency>

<groupId>org.springframework.cloud</groupId>

<artifactId>spring-cloud-starter-config</artifactId>

</dependency>

<!-- actuator监控信息完善 -->

        <dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-actuator</artifactId>

</dependency>

</dependencies>

</project>

(4).配置yml文件

修改的地方有端口、数据库链接、实例id(instance-id)；对外暴露的统一服务实例名一定不能修改(name: microservicecloud-dept)

[1].配置provider8002 yml文件

server:

  port: 8002

mybatis:

  config-location: classpath:mybatis/mybatis.cfg.xml        # mybatis配置文件所在路径

  type-aliases-package: com.hosytem.springcloud.entities    # 所有Entity别名类所在包

  mapper-locations:

  - classpath:mybatis/mapper/**/*.xml                       # mapper映射文件

#name spring.application.name=microservicecloud-dept  很重要很重要很重要

spring:

   application:

    name: microservicecloud-dept

datasource:

    type: com.alibaba.druid.pool.DruidDataSource            # 当前数据源操作类型

    driver-class-name: org.gjt.mm.mysql.Driver              # mysql驱动包

    url: jdbc:mysql://192.168.188.188:3306/cloudDB02              # 数据库名称

    username: root

password: 123456

dbcp2:

      min-idle: 5                                           # 数据库连接池的最小维持连接数

      initial-size: 5                                       # 初始化连接数

      max-total: 5                                          # 最大连接数

      max-wait-millis: 200                                  # 等待连接获取的最大超时时间

eureka:

  client: #客户端注册进eureka服务列表内

    service-url:

#      defaultZone: http://localhost:7001/eureka

      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/

instance:

    instance-id: microservicecloud-dept8002

prefer-ip-address: true     #访问路径可以显示IP地址

info:

  app.name: hosystem-microservicecloud

company.name: www.hosystem.com

build.artifactId: $project.artifactId$

build.version: $project.version$

[2].配置provider8003 yml文件

server:

  port: 8003

mybatis:

  config-location: classpath:mybatis/mybatis.cfg.xml        # mybatis配置文件所在路径

  type-aliases-package: com.hosytem.springcloud.entities    # 所有Entity别名类所在包

  mapper-locations:

  - classpath:mybatis/mapper/**/*.xml                       # mapper映射文件

#name spring.application.name=microservicecloud-dept  很重要很重要很重要

spring:

   application:

    name: microservicecloud-dept

datasource:

    type: com.alibaba.druid.pool.DruidDataSource            # 当前数据源操作类型

    driver-class-name: org.gjt.mm.mysql.Driver              # mysql驱动包

    url: jdbc:mysql://192.168.188.188:3306/cloudDB03              # 数据库名称

    username: root

password: 123456

dbcp2:

      min-idle: 5                                           # 数据库连接池的最小维持连接数

      initial-size: 5                                       # 初始化连接数

      max-total: 5                                          # 最大连接数

      max-wait-millis: 200                                  # 等待连接获取的最大超时时间

eureka:

  client: #客户端注册进eureka服务列表内

    service-url:

#      defaultZone: http://localhost:7001/eureka

      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/

instance:

    instance-id: microservicecloud-dept8003

prefer-ip-address: true     #访问路径可以显示IP地址

info:

  app.name: hosystem-microservicecloud

company.name: www.hosystem.com

build.artifactId: $project.artifactId$

build.version: $project.version$

(5).配置主启动类

[1].DeptProvider8002_App

[2].DeptProvider8002_App

(6).创建数据库database8002、database8003

新建8002/8003数据库，各自微服务分别连各自的数据库。

[1].创建database8002

DROP DATABASE IF EXISTS cloudDB02;

CREATE DATABASE cloudDB02 CHARACTER SET UTF8;

USE cloudDB02;

CREATE TABLE dept

(

deptno BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT,

dname VARCHAR(60),

db_source   VARCHAR(60)

);

INSERT INTO dept(dname,db_source) VALUES('开发部',DATABASE());

INSERT INTO dept(dname,db_source) VALUES('人事部',DATABASE());

INSERT INTO dept(dname,db_source) VALUES('财务部',DATABASE());

INSERT INTO dept(dname,db_source) VALUES('市场部',DATABASE());

INSERT INTO dept(dname,db_source) VALUES('运维部',DATABASE());

SELECT * FROM dept;

[2].创建database8003

DROP DATABASE IF EXISTS cloudDB03;

CREATE DATABASE cloudDB03 CHARACTER SET UTF8;

USE cloudDB03;

CREATE TABLE dept

(

deptno BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT,

dname VARCHAR(60),

db_source   VARCHAR(60)

);

INSERT INTO dept(dname,db_source) VALUES('开发部',DATABASE());

INSERT INTO dept(dname,db_source) VALUES('人事部',DATABASE());

INSERT INTO dept(dname,db_source) VALUES('财务部',DATABASE());

INSERT INTO dept(dname,db_source) VALUES('市场部',DATABASE());

INSERT INTO dept(dname,db_source) VALUES('运维部',DATABASE());

SELECT * FROM dept;

(7).启动eureka、provider、consumer

启动3个eureka集群配置区,在启动provider后，我们需要随便打开一个eureka看provider是否都注册上了。

启动3个provider微服务并各自测试通过

http://localhost:8001/dept/list

http://localhost:8002/dept/list

http://localhost:8003/dept/list

启动microservicecloud-consumer-dept-80

(8).访问Dept微服务

客户端通过Ribbo完成负载均衡并访问上一步的Dept微服务

http://localhost/consumer/dept/list

注意观察看到返回的数据库名字，各不相同，负载均衡实现 

(9).总结

Ribbon其实就是一个软负载均衡的客户端组件，他可以和其他所需请求的客户端结合使用，和eureka结合只是其中的一个实例。

4.Ribbon核心组件

(1).查看IRle接口

(2).查看IRleILoadBalancer接口

(3).查看AbstractLoadBalancer接口

(4).使用RandomRule算法

修改consumer-dept-80的ConfigBean.java.

package com.hosystem.springcloud.cfgbeans;

import com.netflix.loadbalancer.IRule;

import com.netflix.loadbalancer.RandomRule;

import com.netflix.loadbalancer.RetryRule;

import com.netflix.loadbalancer.RoundRobinRule;

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();

}

//选择我们使用的算法

    // RoundRobinRule:轮询

    // RandomRule:随机

    // AvailabilityFilteringRule:先过滤多次访问故障处于断路器跳闸状态的服务，还有并发的连接数量超过阈值的服务，然后对剩余的服务列表按照轮询策略进行访问

    // WeightedResponseTimeRule:根据平均响应时间计算所有服务的权重，响应时间越快服务权重越大被选中的概率越高。刚启动时如果统计信息不足，则使用RoundRobinRule策略，等统计信息足够,会切换到WeightedResponseTimeRule

    // RetryRule:先按照RoundRobinRule的策略获取服务，如果获取服务失败则在指定时间内会进行重试，获取可用的服务

    // BestAvailableRule:会先过滤掉由于多次访问故障而处于断路器跳闸状态的服务，然后选择一个并发量最小的服务

    // ZoneAvoidanceRule:默认规则,复合判断server所在区域的性能和server的可用性选择服务器

    @Bean

public IRule myRule(){

//        return new RoundRobinRule(); //轮询算法

//        return new RandomRule();    //随机算法

        return new RetryRule();     //先按照RoundRobinRule的策略获取服务，如果获取服务失败则在指定时间内会进行重试，获取可用的服务

    }

}

//applicationContext.xml  ---> @Configuration public class ConfigBean {}

//<bean id=UserService" class="com.hosystem.tmall.UserServiceImple>

5.Ribbon自定义

修改microservicecloud-consumer-dept-80

(1).修改主启动类

修改consumer-dept-80的主启动类

package com.hosystem.springcloud;

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="MICROSERVICECLOUD-DEPT",configuration=MySelfRule.class) //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

public class DeptConsumer80_App

{

public static void main(String[] args)

{

SpringApplication.run(DeptConsumer80_App.class, args);

}

}

(2).配置事项

官方文档明确给出了警告：这个自定义配置类不能放在@ComponentScan所扫描的当前包下以及子包下，否则我们自定义的这个配置类就会被所有的Ribbon客户端所共享，也就是说我们达不到特殊化定制的目的了。

简单说，就是我们不能够在主启动类(DeptConsumer80_App)所在的包及其子包下创建我们自定义规则类。

如，我们新创建了myrule包，不能够创建在springcloud包下，因为主启动类在springcloud包下了。

(3).自定义步骤

[1].新建package

根据配置事项，我们得知需要重新创建一个包不能和主启动类在一个包下。我们创建com.hosystem.myrule包。

[2].自定义Robbin规则类

package com.hosystem.myrule;

import com.netflix.loadbalancer.IRule;

import com.netflix.loadbalancer.RandomRule;

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

    }

}

[3].修改主启动类

package com.hosystem.springcloud;

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="MICROSERVICECLOUD-DEPT",configuration=MySelfRule.class) //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

public class DeptConsumer80_App

{

public static void main(String[] args)

{

SpringApplication.run(DeptConsumer80_App.class, args);

}

}

[4].测试

http://localhost/consumer/dept/list

(4).自定义规则深度解析

依旧轮询策略，但是加上新需求，每个服务器要求被调用5次。也即以前是每台机器一次，现在是每台机器5次。

[1].源码解析

https://github.com/Netflix/ribbon/blob/master/ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/RandomRule.java

[2].RandomRule_Hosystem.java

参考源码修改为我们需求要求的RandomRule_Hosystem.java

package com.hosystem.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;

public class RandomRule_Hosystem extends AbstractLoadBalancerRule{

//total = 0 当total==5时 指向才能往下走

    //index = 0 当前对外提供的服务器地址

    //当total从5置为0时 我们index=1

    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

    /**

     * Randomly choose from all living servers

     */

//    @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "RCN_REDUNDANT_NULLCHECK_OF_NULL_VALUE")

    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 = chooseRandomInt(serverCount);

//            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

            //分析，因为我们需要访问5次 但是微服务只有8001 8002 8003三台 所以我们需要设定currentIndex>=upList.size()时重新从8001开始

            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;

}

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 iClientConfig) {

}

}

[3].MySelfRule.java

package com.hosystem.myrule;

import com.netflix.loadbalancer.IRule;

import com.netflix.loadbalancer.RandomRule;

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 RandomRule_Hosystem();  //自定义每台机器访问5次

    }

}

[4].测试

http://localhost/consumer/dept/list

参考文档：

https://baike.baidu.com/item/F5%E6%96%B9%E6%A1%88/1121377?fr=aladdin

https://github.com/Netflix/ribbon/wiki

https://github.com/Netflix/ribbon/wiki/Getting-Started

https://github.com/Netflix/ribbon/blob/master/ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/RandomRule.java