SpringCloud客戶端的負(fù)載均衡Ribbon的實(shí)現(xiàn)

更新時(shí)間：2018年06月20日 14:03:19 作者：lfalex

微服務(wù)架構(gòu)，不可避免的存在單個(gè)微服務(wù)有多個(gè)實(shí)例，這篇文章主要介紹了SpringCloud客戶端的負(fù)載均衡Ribbon的實(shí)現(xiàn)，小編覺得挺不錯(cuò)的，現(xiàn)在分享給大家，也給大家做個(gè)參考。一起跟隨小編過來看看吧

前言：微服務(wù)架構(gòu)，不可避免的存在單個(gè)微服務(wù)有多個(gè)實(shí)例，那么客戶端如何將請求分?jǐn)偟蕉鄠€(gè)微服務(wù)的實(shí)例上呢？這里我們就需要使用負(fù)載均衡了

一、Ribbon簡介

Ribbon是Netflix發(fā)布的負(fù)載均衡器，它有助于控制HTTP和TCP客戶端的行為。為Ribbon配置服務(wù)提供者地址列表后，Ribbon就可基于某種負(fù)載均衡算法，自動地幫助服務(wù)消費(fèi)者去請求。Ribbon默認(rèn)為我們提供了很多的負(fù)載均衡算法，例如：輪詢，隨機(jī)等，也可自定義；

Ribbon的GitHub： https://github.com/Netflix/ribbon

而在SpringCloud中使用Ribbon和Eureka時(shí)，Ribbon會自動從EurekaServer中獲取服務(wù)提供者地址列表，并基于負(fù)載均衡算法。

二、Ribbon實(shí)戰(zhàn)

1、創(chuàng)建EurekaServer，EurekaClient1，EurekaClient2，之前已經(jīng)說過了Eureka的使用，這里直接上代碼：

EurekaServer：

ServerApplication.java

@SpringBootApplication
@EnableEurekaServer
public class ServerApplication {

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

}

pom.xml

<?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">
 <modelVersion>4.0.0</modelVersion>

 <groupId>com.cn</groupId>
 <artifactId>eureka-ribbon-server</artifactId>
 <version>1.0-SNAPSHOT</version>

 <properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <java.version>1.8</java.version>
 </properties>

 <parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.5.13.RELEASE</version>
 </parent>

 <dependencies>
  <dependency>
   <groupId>org.springframework.</groupId>
   <artifactId></artifactId>
  </dependency>
  <dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-eureka-server</artifactId>
  </dependency>
 </dependencies>
 <dependencyManagement>
  <dependencies>
   <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-dependencies</artifactId>
    <version>Edgware.SR3</version>
    <type>pom</type>
    <scope>import</scope>
   </dependency>
  </dependencies>
 </dependencyManagement>
 <!-- 添加spring-boot的maven插件 -->
 <build>
  <plugins>
   <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
   </plugin>
  </plugins>
 </build>
</project>

application.properties

server.port=8761
#注意：這兩個(gè)配置eureka默認(rèn)為true，要改成false，否則會報(bào)錯(cuò)，connot connect server
#表示是否將自己注冊在EurekaServer上
eureka.client.register-with-eureka=false
#表示是否從EurekaServer獲取注冊信息
eureka.client.fetch-registry=false

eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

EurekaClient1:

pom.xml

<?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">
 <modelVersion>4.0.0</modelVersion>

 <groupId>com.cn</groupId>
 <artifactId>eureka-ribbon-client</artifactId>
 <version>1.0-SNAPSHOT</version>

 <properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <java.version>1.8</java.version>
 </properties>

 <parent>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-parent</artifactId>
  <version>1.5.13.RELEASE</version>
 </parent>

 <dependencies>
  <dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-ribbon</artifactId>
  </dependency>
  <dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-eureka</artifactId>
  </dependency>
 </dependencies>
 <dependencyManagement>
  <dependencies>
   <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-dependencies</artifactId>
    <version>Edgware.SR3</version>
    <type>pom</type>
    <scope>import</scope>
   </dependency>
  </dependencies>
 </dependencyManagement>
 <!-- 添加spring-boot的maven插件 -->
 <build>
  <plugins>
   <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
   </plugin>
  </plugins>
 </build>
</project>

server.port=8762
spring.application.name=client-8762
eureka.client.service-url.defaultZone=http://localhost:8761/eureka/

而在啟動類中加入RestTemplate遠(yuǎn)程調(diào)用實(shí)例到容器中，并且添加LoadBalanced注解，使RestTemplate具備負(fù)載均衡的能力：

@SpringBootApplication
@EnableDiscoveryClient
public class ClientApplication {

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

  /** 
   * @Description: 加入@LoadBalanced注解，就可以為RestTemplate加入負(fù)載均衡的能力 
   * @Param:
   * @return: 
   * @Author: 
   * @Date: 2018/6/15 
   */ 
  @Bean
  @LoadBalanced
  public RestTemplate getRestTemplate() {
    return new RestTemplate();
  }

}

創(chuàng)建Controller，注入RestTemplate、LoadBalancerClient實(shí)例：

package com.cn.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.client.RestTemplate;

/**
 * @program: springcloud-example
 * @description:
 * @author: 
 * @create: 2018-06-15 15:55
 **/
@Controller
public class RibbonController {

  @Autowired
  private LoadBalancerClient loadBalancerClient;

  @Autowired
  private RestTemplate restTemplate;

  @GetMapping("/loadInstance")
  @ResponseBody
  public String loadInstance() {
    ServiceInstance choose = this.loadBalancerClient.choose("client-87");
    System.out.println(choose.getServiceId()+":"+choose.getHost()+":"+choose.getPort());
    return choose.getServiceId() + ":" + choose.getHost() + ":" + choose.getPort();
  }

}

package com.cn;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

/**
 * @program: springcloud-example
 * @description:
 * @author: 535504
 * @create: 2018-06-15 16:05
 **/
@SpringBootApplication
@EnableDiscoveryClient
public class ClientApplication {

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

}

EurekaClient2：

pom.xml與EurekaClient1中一致

application.xml:

server.port=8763
spring.application.name=client-87
eureka.client.service-url.defaultZone=http://localhost:8761/eureka

ClientController.java:

package com.cn.contorller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * @program: springcloud-example
 * @description:
 * @author: 
 * @create: 2018-06-15 16:12
 **/
@Controller
public class ClientController {

  @GetMapping("/getUser")
  @ResponseBody
  public String getUser() {
    System.out.println("獲取用戶成功");
    return "獲取用戶成功";
  }

}

2、啟動順序：

①、依次啟動EurekaServer =》 EurekaClient1 =》 EurekaClient2 ；

②、然后將EurekaClient2中的application.properties的server.port=8763改為server.port=8764，再次啟動該項(xiàng)目;

③、打開EurekaServer的配置頁面（http://localhost:8761/），如下：