springcloud学习（三）之Ribbon

一，介绍

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，随即连接等）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。

二、开发

1、新建项目hjduan.spring.cloud.ribbon pom如下

<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>    <parent>        <groupId>com.hjduan.spring.cloud</groupId>        <artifactId>hjduan.spring.cloud</artifactId>        <version>0.0.1-SNAPSHOT</version>    </parent>    <artifactId>hjduan.spring.cloud.ribbon</artifactId>    <dependencies>        <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.boot</groupId>            <artifactId>spring-boot-starter-web</artifactId>        </dependency>    </dependencies>    <build>        <plugins>            <plugin>                <groupId>org.apache.maven.plugins</groupId>                <artifactId>maven-compiler-plugin</artifactId>            </plugin>        </plugins>    </build></project>

2、application.yml配置

server:  port: 8764eureka:  client:    serviceUrl:      defaultZone: http://admin:admin@localhost:8761/eureka/  instance:    prefer-ip-address: true    instance-id: ${spring.application.name}:${spring.application.instance_id:${server.port}}spring:  application:    name: hjduan-spring-cloud-ribbon

3、编写一个服务消费类 RibbonHelloWordService

package com.hjduan.spring.cloud.ribbon.service;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import org.springframework.web.client.RestTemplate;/** * Created by Administrator on 2017/7/11. */@Servicepublic class RibbonHelloWordService {    @Autowired    RestTemplate restTemplate;    public String ribbonHelloWordService(String name) {        return restTemplate.getForObject("http://HJDUAN-SPRING-CLOUD-CONSUMER/hi/{name}",String.class,name);    }}

4、编写controller

package com.hjduan.spring.cloud.ribbon.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RestController;import com.hjduan.spring.cloud.ribbon.service.RibbonHelloWordService;/** *  *  *     作者：     段浩杰              2017年7月25日 */@RestControllerpublic class RibbonHelloWordController {    @Autowired    private RibbonHelloWordService ribbonHelloWordService;    @GetMapping(value = "/hi/{name}")    public String ribbonHelloWord(@PathVariable String name) {        return ribbonHelloWordService.ribbonHelloWordService(name);    }}

5、编写启动类

package com.hjduan.spring.cloud.ribbon;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.cloud.client.loadbalancer.LoadBalanced;import org.springframework.cloud.netflix.eureka.EnableEurekaClient;import org.springframework.context.annotation.Bean;import org.springframework.web.client.RestTemplate;/** * Ribbon 做负载客户端负载均衡 *  * 作者： 段浩杰 2017年7月25日 */@EnableEurekaClient@SpringBootApplicationpublic class RibbinApplicationConfiguration {    public static void main(String[] args) {        new SpringApplication(RibbinApplicationConfiguration.class).run(args);    }    /**     * @ LoadBalanced注册表明，这个restRemplate是负载均衡的。 @return     */    @Bean    @LoadBalanced    public RestTemplate restTemplate() {        return new RestTemplate();    }}

6、运行

然后分别启动上一节的hjduan.spring.cloud.eureka， hjduan.spring.cloud.consumer，之后修改hjduan.spring.cloud.consumer的端口在启动一次。之后再启动这个项目访问地址http://localhost:8764/hi/123，运行两次观察浏览器的显示。