java版b2b2c社交電商spring cloud分布式微服務（二） 服務消費者（rest+ribbon）

一、ribbon簡介

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.

—–摘自官網

ribbon是一個負載均衡客戶端，可以很好的控制htt和tcp的一些行為。Feign默認集成了ribbon。

ribbon 已經默認實現了這些配置bean：

• IClientConfig ribbonClientConfig: DefaultClientConfigImpl

• IRule ribbonRule: ZoneAvoidanceRule

• IPing ribbonPing: NoOpPing

• ServerList ribbonServerList: ConfigurationBasedServerList

• ServerListFilter ribbonServerListFilter: ZonePreferenceServerListFilter

• ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer

二、準備工作

這一篇文章基于上一篇文章的工程，啟動eureka-server 工程；啟動service-hi工程，它的端口為8762；將service-hi的配置文件的端口改為8763,并啟動，這時你會發現：service-hi在eureka-server注冊了2個實例，這就相當于一個小的集群。訪問localhost:8761如圖所示：

三、建一個服務消費者

重新新建一個spring-boot工程，取名為：service-ribbon;?
在它的pom.xml文件分別引入起步依賴spring-cloud-starter-eureka、spring-cloud-starter-ribbon、spring-boot-starter-web，代碼如下：

<?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務的注冊中心地址為http://localhost:8761/eureka/，程序名稱為 service-ribbon，程序端口為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

在工程的啟動類中,通過@EnableDiscoveryClient向服務中心注冊；并且向程序的ioc注入一個bean: restTemplate;并通過@LoadBalanced注解表明這個restRemplate開啟負載均衡的功能。

@SpringBootApplication
@EnableDiscoveryClient
public class ServiceRibbonApplication {public static void main(String[] args) {SpringApplication.run(ServiceRibbonApplication.class, args);}@Bean@LoadBalancedRestTemplate restTemplate() {return new RestTemplate();}}

寫一個測試類HelloService，通過之前注入ioc容器的restTemplate來消費service-hi服務的“/hi”接口，在這里我們直接用的程序名替代了具體的url地址，在ribbon中它會根據服務名來選擇具體的服務實例，根據服務實例在請求的時候會用具體的url替換掉服務名，代碼如下：

@Service
public class HelloService {@AutowiredRestTemplate restTemplate;public String hiService(String name) {return restTemplate.getForObject("http://SERVICE-HI/hi?name="+name,String.class);}}

寫一個controller，在controller中用調用HelloService 的方法，代碼如下：

/*** 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);}}

在瀏覽器上多次訪問http://localhost:8764/hi?name=forezp，瀏覽器交替顯示：

hi forezp,i am from port:8762hi forezp,i am from port:8763

　這說明當我們通過調用restTemplate.getForObject(“http://SERVICE-HI/hi?name=“+name,String.class)方法時，已經做了負載均衡，訪問了不同的端口的服務實例。

代碼架構如下:

需要JAVASpring Cloud大型企業分布式微服務云構建的B2B2C電子商務社交平臺源碼請加企鵝求求：一零三八七七四六二六