SpringCloud 学习 | 第三篇： 服务消费者 Ribbon

Ribbon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，随机连接等）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。简单地说，Ribbon是一个客户端负载均衡器。Ribbon工作时分为两步：第一步先选择 Eureka Server, 它优先选择在同一个Zone且负载较少的Server；第二步再根据用户指定的策略，在从Server取到的服务注册列表中选择一个地址。其中Ribbon提供了多种策略，例如轮询、随机、根据响应时间加权等。创建一个原项目基础上创建一个modelpom.xml中如下
<?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.example</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>2.0.0.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>
<spring-cloud.version>Finchley.M8</spring-cloud.version>
</properties>

<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</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>${spring-cloud.version}</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>配置application.ymleureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/,http://localhost:8760/eureka/ #高可用注册中心
server:
port: 8764

spring:
application:
name: service_ribbon #注册名字启动类添加@EnableEurekaClient注册服务  使用@LoadBalanced注解，为RestTemplate开启负载均衡的能力。@SpringBootApplication
@EnableEurekaClient
public class ServiceRibbonApplication {

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

/**
* 获取RestTemplate示例 通过@LoadBalanced注解开启均衡负载能力.
* @return
*/
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
}

创建controller控制器模拟消费者消费@RestController
public class HiController {

@Autowired
HiService hiService;

@RequestMapping("/hi")
public String hi(String name) {
return hiService.hi(name);
}

}service类@Service
public class HiService {

@Autowired
private RestTemplate restTemplate;
// http://服务提供者的serviceId/url public String hi(String name){
return restTemplate.getForObject("http://SUPPLY-HI/hi?name="+name,String.class);
}
}

测试 多次请求http://localhost:8764/hi?name=forezp 




至此，服务消费者 ribbon编写完成且实现了均衡负载。