Spring Cloud教程二:Ribbon

文章目录
  1. 1. Ribbon简介
  2. 2. 准备工作
  3. 3. 新建一个服务消费者

前一篇讲了服务注册和发现,没有看过的朋友先看上一篇,这篇是在上一篇基础上展开。

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.

Ribbon是负载均衡客户端,可以很好的控制HTTP和TCP客户端的行为。 Feign已经集成了Ribbon。

Spring Cloud Netflix默认为ribbon(BeanType beanName:ClassName)提供以下bean:

  • IClientConfig ribbonClientConfig: DefaultClientConfigImpl

  • IRule ribbonRule: ZoneAvoidanceRule

  • IPing ribbonPing: NoOpPing

  • ServerList<Server> ribbonServerList: ConfigurationBasedServerList

  • ServerListFilter<Server> ribbonServerListFilter: ZonePreferenceServerListFilter

  • ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer

准备工作

这篇文章基于上一篇文章项目,启动eureka-server项目;启动eureka-client项目,端口为8040; 将eureka-client的配置文件端口改为8041,并启动,同一个项目修改端口号,启动多个实例,只需要在IDEA中勾选Allow parallel run

此时你会发现注册服务中注册了两个eureka-client实例,相当于起了2个节点的集群。 访问http://localhost:9090:

新建一个服务消费者

使用Spring Initializr新建一个项目,取名为ribbon-service, 在Spring Cloud Discovery中勾选Eureka Discovery Client,在Spring Cloud Routing中勾选Ribbon,在Web中勾选Spring Web:

创建成功后,项目pom.xml如下:

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<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.9.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.noodles.mars</groupId>
<artifactId>ribbon-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>ribbon-service</name>
<description>Ribbon Service</description>

<properties>
<java.version>1.8</java.version>
<spring-cloud.version>Greenwich.SR3</spring-cloud.version>
</properties>

<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</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-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>${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>

</project>

ribbon-service配置服务中心地址、应用名、端口,配置文件内容:

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server:
port: 8050

spring:
application:
name: ribbon-service

eureka:
client:
service-url:
defaultZone: http://localhost:9090/eureka/

在项目启动类上注解@EnableDiscoveryClient, 开启向服务中心注册;定义一个 RestTemplate Bean, 并注解@LoadBalanced开启负载均衡功能:

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@EnableEurekaClient
@SpringBootApplication
public class RibbonServiceApplication {

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

@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}

}

写一个controller, 通过之前定义的RestTemplate来消费eureka-client服务的/hello接口,url中使用应用名,ribbon会根据应用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:

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@RestController
public class HelloController {

private final RestTemplate restTemplate;

@Autowired
public HelloController(RestTemplate restTemplate) {
this.restTemplate = restTemplate;
}

@GetMapping("/hello")
public String hello(@RequestParam("name") String name) {
return restTemplate.getForObject("http://HELLO-ERUEKA-CLIENT/hello?name=" + name, String.class);
}
}

在浏览器上多次访问 http://localhost:8050/hello?name=Mars :

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Hello, My name is Mars, I'm from port: 8040
Hello, My name is Mars, I'm from port: 8041

这说明负载均衡器已经工作了。

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