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5、Spring Cloud Ribbon

1.Ribbon簡介

(1).Ribbon介紹

  Spring Cloud Ribbon是基於Netflix Ribbon實現的一套客戶端負載均衡的工具。

  Ribbon是Netflix發佈的開源項目，主要功能是提供客戶端的軟件負載均衡算法，將Netflix的中間層服務連接在一起。Ribbon客戶端組件提供一系列完善的配置項如連接超時，重試等。簡單的說，就是在配置文件中列出Load Balancer（簡稱LB）後面所有的機器，Ribbon會自動的幫助你基於某種規則（如簡單輪詢，隨機連接等）去連接這些機器。我們也很容易使用Ribbon實現自定義的負載均衡算法。

(2).Ribbon作用

  Ribbon是基於Netflix Ribbon實現的一套客戶端負載均衡(LB)的工具。

  LB(負載均衡):集中式LB和進程內LB。

  集中式LB：即在服務的消費方和提供方之間使用獨立的LB設施(可以是硬件，如F5, 也可以是軟件，如nginx), 由該設施負責把訪問請求通過某種策略轉發至服務的提供方；

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

  進程內LB：將LB邏輯集成到消費方，消費方從服務註冊中心獲知有哪些地址可用，然後自己再從這些地址中選擇出一個合適的服務器。

  Ribbon就屬於進程內LB，它只是一個類庫，集成於消費方進程，消費方通過它來獲取到服務提供方的地址。

  官方文檔：

//github.com/Netflix/ribbon/wiki

//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相關 –>

    <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=”//maven.apache.org/POM/4.0.0″

         xmlns:xsi=”//www.w3.org/2001/XMLSchema-instance”

         xsi:schemaLocation=”//maven.apache.org/POM/4.0.0 //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>部門微服務消費者</description>–>

 

    <dependencies>

        <dependency><!– 自己定義的api –>

            <!–注意：groupId我們需要由com.hosystem.springcloud 變成com.hosystem就不會出現‘Dependency ‘com.hosystem.springcloud:microservicecloud-api:1.0-SNAPSHOT’ not found’錯誤–>

            <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>

        <!– 修改後立即生效，熱部署 –>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>springloaded</artifactId>

        </dependency>

        <dependency>

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

            <artifactId>spring-boot-devtools</artifactId>

        </dependency>

 

        <!– Ribbon相關 –>

        <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的服務註冊地址。

  修改部分：

eureka:

  client:

    register-with-eureka: false

    service-url:

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

  完整部分：

server:

  port: 80

 

eureka:

  client:

    register-with-eureka: false

    service-url:

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

(3).修改ConfigBean.java

  對ConfigBean進行新註解@LoadBalanced,獲得Rest時加入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是基於Netflix Ribbon實現的一套客戶端負載均衡的工具。

    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

  主啟動類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客戶端訪問類

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:這裡一定不能忘記註解@RestController 否則出現404;

public class DeptController_Consumer {

 

    /**

     *  使用restTemplate訪問restful接口非常的簡單;

     *  (url, requestMap, ResponseBean.class)三個參數代表REST請求地址、請求參數、HTTP響應轉換被轉換成的對象類型

     */

//    private static final String REST_URL_PREFIX = “//localhost:8001”;

    //修改為微服務名 實現名字訪問微服務

    private static final String REST_URL_PREFIX = “//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”):壓制警告，因為我們使用了過期的方法

    @SuppressWarnings(“unchecked”)

    @RequestMapping(value=“/consumer/dept/list”)

    public List<Dept> list()

    {

        return restTemplate.getForObject(REST_URL_PREFIX+“/dept/list”, List.class);

    }

 

    //測試@EnableDiscoveryClient,消費端可以調用服務發現

    @RequestMapping(value=“/consumer/dept/discovery”)

    public Object discovery()

    {

        return restTemplate.getForObject(REST_URL_PREFIX+“/dept/discovery”, Object.class);

    }

}

/**

 *  JDBC    Spring JDBCTemplate

 *          Spring RestTemplate

 */

(6).啟動eureka、provider、consumer

  先啟動3個eureka7001、eureka7002、eureka7003集群後，再啟動microservicecloud-provider-dept-8001並註冊進eureka，最後啟動microservicecloud-consumer-dept-80。

 

(7).測試

//localhost/consumer/dept/get/1

//localhost/consumer/dept/list

//localhost/consumer/dept/add?dname=大數據部

 

 

(8).總結

  Ribbon和Eureka整合後Consumer可以直接調用服務而不用再關心地址和端口號

3.Ribbon負載均衡

 

(1).Ribbon架構介紹

 

  Ribbon在工作時分成兩步：第一步先選擇 EurekaServer ,它優先選擇在同一個區域內負載較少的server.第二步再根據用戶指定的策略，在從server取到的服務註冊列表中選擇一個地址。其中Ribbon提供了多種策略：比如輪詢、隨機和根據響應時間加權。

(2).創建provider8002、provider8003

 

[1].創建工程provider8002

[2].創建工程provider8003

(3).配置pom文件

[1].配置provider8002 pom文件

<?xml version=”1.0″ encoding=”UTF-8″?>

<project xmlns=”//maven.apache.org/POM/4.0.0″

         xmlns:xsi=”//www.w3.org/2001/XMLSchema-instance”

         xsi:schemaLocation=”//maven.apache.org/POM/4.0.0 //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><!– 引入自己定義的api通用包，可以使用Dept部門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>

        <!– 修改後立即生效，熱部署 –>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>springloaded</artifactId>

        </dependency>

        <dependency>

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

            <artifactId>spring-boot-devtools</artifactId>

        </dependency>

 

        <!– 將微服務provider側註冊進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監控信息完善 –>

        <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=”//maven.apache.org/POM/4.0.0″

         xmlns:xsi=”//www.w3.org/2001/XMLSchema-instance”

         xsi:schemaLocation=”//maven.apache.org/POM/4.0.0 //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><!– 引入自己定義的api通用包，可以使用Dept部門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>

        <!– 修改後立即生效，熱部署 –>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>springloaded</artifactId>

        </dependency>

        <dependency>

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

            <artifactId>spring-boot-devtools</artifactId>

        </dependency>

 

        <!– 將微服務provider側註冊進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監控信息完善 –>

        <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、數據庫鏈接、實例id(instance-id)；對外暴露的統一服務實例名一定不能修改(name: microservicecloud-dept)

[1].配置provider8002 yml文件

server:

  port: 8002

 

mybatis:

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

  type-aliases-package: com.hosytem.springcloud.entities    # 所有Entity別名類所在包

  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            # 當前數據源操作類型

    driver-class-name: org.gjt.mm.mysql.Driver              # mysql驅動包

    url: jdbc:mysql://192.168.188.188:3306/cloudDB02              # 數據庫名稱

    username: root

    password: 123456

    dbcp2:

      min-idle: 5                                           # 數據庫連接池的最小維持連接數

      initial-size: 5                                       # 初始化連接數

      max-total: 5                                          # 最大連接數

      max-wait-millis: 200                                  # 等待連接獲取的最大超時時間

 

eureka:

  client: #客戶端註冊進eureka服務列表內

    service-url:

#      defaultZone: //localhost:7001/eureka

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

  instance:

    instance-id: microservicecloud-dept8002

    prefer-ip-address: true     #訪問路徑可以顯示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配置文件所在路徑

  type-aliases-package: com.hosytem.springcloud.entities    # 所有Entity別名類所在包

  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            # 當前數據源操作類型

    driver-class-name: org.gjt.mm.mysql.Driver              # mysql驅動包

    url: jdbc:mysql://192.168.188.188:3306/cloudDB03              # 數據庫名稱

    username: root

    password: 123456

    dbcp2:

      min-idle: 5                                           # 數據庫連接池的最小維持連接數

      initial-size: 5                                       # 初始化連接數

      max-total: 5                                          # 最大連接數

      max-wait-millis: 200                                  # 等待連接獲取的最大超時時間

 

eureka:

  client: #客戶端註冊進eureka服務列表內

    service-url:

#      defaultZone: //localhost:7001/eureka

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

  instance:

    instance-id: microservicecloud-dept8003

    prefer-ip-address: true     #訪問路徑可以顯示IP地址

info:

  app.name: hosystem-microservicecloud

  company.name: www.hosystem.com

  build.artifactId: $project.artifactId$

  build.version: $project.version$

(5).配置主啟動類

[1].DeptProvider8002_App

 

[2].DeptProvider8002_App

 

(6).創建數據庫database8002、database8003

  新建8002/8003數據庫，各自微服務分別連各自的數據庫。

[1].創建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(‘開發部’,DATABASE());

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

INSERT INTO dept(dname,db_source) VALUES(‘財務部’,DATABASE());

INSERT INTO dept(dname,db_source) VALUES(‘市場部’,DATABASE());

INSERT INTO dept(dname,db_source) VALUES(‘運維部’,DATABASE());

 

SELECT * FROM dept;

[2].創建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(‘開發部’,DATABASE());

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

INSERT INTO dept(dname,db_source) VALUES(‘財務部’,DATABASE());

INSERT INTO dept(dname,db_source) VALUES(‘市場部’,DATABASE());

INSERT INTO dept(dname,db_source) VALUES(‘運維部’,DATABASE());

 

SELECT * FROM dept;

(7).啟動eureka、provider、consumer

  啟動3個eureka集群配置區,在啟動provider後，我們需要隨便打開一個eureka看provider是否都註冊上了。

 

  啟動3個provider微服務並各自測試通過

//localhost:8001/dept/list

//localhost:8002/dept/list

//localhost:8003/dept/list

 

  啟動microservicecloud-consumer-dept-80

 

(8).訪問Dept微服務

  客戶端通過Ribbo完成負載均衡並訪問上一步的Dept微服務

//localhost/consumer/dept/list

  注意觀察看到返回的數據庫名字，各不相同，負載均衡實現 

(9).總結

  Ribbon其實就是一個軟負載均衡的客戶端組件，他可以和其他所需請求的客戶端結合使用，和eureka結合只是其中的一個實例。

4.Ribbon核心組件

 

(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是基於Netflix Ribbon實現的一套客戶端負載均衡的工具。

    public RestTemplate getRestTemplate()

    {

        return new RestTemplate();

    }

 

    //選擇我們使用的算法

    // RoundRobinRule:輪詢

    // RandomRule:隨機

    // AvailabilityFilteringRule:先過濾多次訪問故障處於斷路器跳閘狀態的服務，還有並發的連接數量超過閾值的服務，然後對剩餘的服務列表按照輪詢策略進行訪問

    // WeightedResponseTimeRule:根據平均響應時間計算所有服務的權重，響應時間越快服務權重越大被選中的概率越高。剛啟動時如果統計信息不足，則使用RoundRobinRule策略，等統計信息足夠,會切換到WeightedResponseTimeRule

    // RetryRule:先按照RoundRobinRule的策略獲取服務，如果獲取服務失敗則在指定時間內會進行重試，獲取可用的服務

    // BestAvailableRule:會先過濾掉由於多次訪問故障而處於斷路器跳閘狀態的服務，然後選擇一個並發量最小的服務

    // ZoneAvoidanceRule:默認規則,複合判斷server所在區域的性能和server的可用性選擇服務器

    @Bean

    public IRule myRule(){

 

//        return new RoundRobinRule(); //輪詢算法

//        return new RandomRule();    //隨機算法

        return new RetryRule();     //先按照RoundRobinRule的策略獲取服務，如果獲取服務失敗則在指定時間內會進行重試，獲取可用的服務

    }

}

 

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

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

5.Ribbon自定義

 

  修改microservicecloud-consumer-dept-80

(1).修改主啟動類

  修改consumer-dept-80的主啟動類

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) //在啟動該微服務的時候就能去加載我們的自定義Ribbon配置類，從而使配置生效

public class DeptConsumer80_App

{

    public static void main(String[] args)

    {

        SpringApplication.run(DeptConsumer80_App.class, args);

    }

}

(2).配置事項

  官方文檔明確給出了警告：這個自定義配置類不能放在@ComponentScan所掃描的當前包下以及子包下，否則我們自定義的這個配置類就會被所有的Ribbon客戶端所共享，也就是說我們達不到特殊化定製的目的了。

  簡單說，就是我們不能夠在主啟動類(DeptConsumer80_App)所在的包及其子包下創建我們自定義規則類。

 

  如，我們新創建了myrule包，不能夠創建在springcloud包下，因為主啟動類在springcloud包下了。

 

(3).自定義步驟

[1].新建package

  根據配置事項，我們得知需要重新創建一個包不能和主啟動類在一個包下。我們創建com.hosystem.myrule包。

[2].自定義Robbin規則類

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默認是輪詢，我自定義為隨機

    }

}

[3].修改主啟動類

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) //在啟動該微服務的時候就能去加載我們的自定義Ribbon配置類，從而使配置生效

public class DeptConsumer80_App

{

    public static void main(String[] args)

    {

        SpringApplication.run(DeptConsumer80_App.class, args);

    }

}

[4].測試

//localhost/consumer/dept/list

(4).自定義規則深度解析

  依舊輪詢策略，但是加上新需求，每個服務器要求被調用5次。也即以前是每台機器一次，現在是每台機器5次。

[1].源碼解析

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

[2].RandomRule_Hosystem.java

  參考源碼修改為我們需求要求的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 當total==5時 指向才能往下走

    //index = 0 當前對外提供的服務器地址

    //當total從5置為0時 我們index=1

    private int total = 0;    //總共被調用的次數，目前要求每台被調用5次

    private int currentIndex = 0;//當前提供服務的機器號

 

    /**

     * 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;    //總共被調用的次數，目前要求每台被調用5次

//            private int currentIndex = 0;//當前提供服務的機器號

            //分析，因為我們需要訪問5次 但是微服務只有8001 8002 8003三台 所以我們需要設定currentIndex>=upList.size()時重新從8001開始

            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默認是輪詢，我自定義為隨機

 

        return  new RandomRule_Hosystem();  //自定義每台機器訪問5次

    }

}

[4].測試

//localhost/consumer/dept/list

參考文檔：

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

//github.com/Netflix/ribbon/wiki

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

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

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