一、ribbon简介
Ribbon is a client side load balancer which gives you a lot of control over the behaviour of HTTP and TCP clients. Feign already uses Ribbon, so if you are using @FeignClient then this section also applies.
—–摘自官网
ribbon是一个负载均衡客户端,可以很好的控制htt和tcp的一些行为。Feign默认集成了ribbon。
ribbon 已经默认实现了这些配置bean:
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IClientConfig ribbonClientConfig: DefaultClientConfigImpl
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IRule ribbonRule: ZoneAvoidanceRule
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IPing ribbonPing: NoOpPing
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ServerList ribbonServerList: ConfigurationBasedServerList
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ServerListFilter ribbonServerListFilter: ZonePreferenceServerListFilter
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ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer
二、准备工作
这一篇文章基于上一篇文章的工程,启动eureka-server 工程;启动service-hi工程,它的端口为8762;将service-hi的配置文件的端口改为8763,并启动,这时你会发现:service-hi在eureka-server注册了2个实例,这就相当于一个小的集群。访问localhost:8761如图所示:
三、建一个服务消费者
重新新建一个spring-boot工程,取名为:service-ribbon;
在它的pom.xml文件分别引入起步依赖spring-cloud-starter-eureka、spring-cloud-starter-ribbon、spring-boot-starter-web,代码如下:
<?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.forezp</groupId><artifactId>service-ribbon</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>service-ribbon</name><description>Demo project for Spring Boot</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.5.2.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version></properties><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><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>Dalston.RC1</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build><repositories><repository><id>spring-milestones</id><name>Spring Milestones</name><url>https://repo.spring.io/milestone</url><snapshots><enabled>false</enabled></snapshots></repository></repositories></project>
在工程的配置文件指定服务的注册中心地址为http://localhost:8761/eureka/,程序名称为 service-ribbon,程序端口为8764。配置文件application.yml如下:
eureka:client:serviceUrl:defaultZone: http://localhost:8761/eureka/ server:port: 8764 spring:application:name: service-ribbon
在工程的启动类中,通过@EnableDiscoveryClient向服务中心注册;并且向程序的ioc注入一个bean: restTemplate;并通过@LoadBalanced注解表明这个restRemplate开启负载均衡的功能。
@SpringBootApplication @EnableDiscoveryClient public class ServiceRibbonApplication {public static void main(String[] args) {SpringApplication.run(ServiceRibbonApplication.class, args);}@Bean@LoadBalancedRestTemplate restTemplate() {return new RestTemplate();}}
写一个测试类HelloService,通过之前注入ioc容器的restTemplate来消费service-hi服务的“/hi”接口,在这里我们直接用的程序名替代了具体的url地址,在ribbon中它会根据服务名来选择具体的服务实例,根据服务实例在请求的时候会用具体的url替换掉服务名,代码如下:
@Service public class HelloService {@AutowiredRestTemplate restTemplate;public String hiService(String name) {return restTemplate.getForObject("http://SERVICE-HI/hi?name="+name,String.class);}}
写一个controller,在controller中用调用HelloService 的方法,代码如下:
/*** Created by fangzhipeng on 2017/4/6.*/ @RestController public class HelloControler {@AutowiredHelloService helloService;@RequestMapping(value = "/hi")public String hi(@RequestParam String name){return helloService.hiService(name);}}
在浏览器上多次访问http://localhost:8764/hi?name=forezp,浏览器交替显示:
hi forezp,i am from port:8762hi forezp,i am from port:8763
这说明当我们通过调用restTemplate.getForObject(“http://SERVICE-HI/hi?name=“+name,String.class)方法时,已经做了负载均衡,访问了不同的端口的服务实例。
代码架构如下:
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