SpringCloud-服务的消费者(rest+ribbon)

在微服务架构中，业务都会被拆分成一个独立的服务，服务与服务的通讯是基于http restful的。Spring Cloud有两种服务调用方式，一种是ribbon+restTemplate,另一种是feign，先来说下ribbon+rest

Ribbon简介

Ribbon是一个负载均衡客户端，可以很好的控制http和tcp的一些行为。Feign默认集成了ribbon
实现负载均衡，我们可以通过服务器端和客户端做负载均衡。服务器端做负载均衡，可以使用Nginx。而客户端做负载均衡，就是客户端有一个组件，知道有哪些可用的微服务，实现一个负载均衡算法。
Ribbon工作流程主要分为两步:
第一：先选择Eureka Server，优先选择在同一个Zone且负载较少的Server
第二：再根据用户指定的策略，再从server取到的服务注册列表中选择一个地址。其中Ribbon提供了很多种策略，例如轮询round bin ，随机random，很具响应时间加权

Ribbon已经默认实现了这些配置bean
IClientConfig ribbonClientConfig: DefaultClientConfigImpl
IRule ribbonRule: ZoneAvoidanceRule
IPing ribbonPing: NoOpPing
ServerList ribbonServerList: ConfigurationBasedServerList
ServerListFilter ribbonServerListFilter: ZonePreferenceServerListFilter
ILoadBalancer ribbonLoadBalancer: ZoneAwareLoadBalancer

项目创建

新建一个Eureka Client项目

pom文件如下

<?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.SpringCloud</groupId>

   <artifactId>service-ribbon</artifactId>

   <version>0.0.1-SNAPSHOT</version>

   <packaging>jar</packaging>

   <name>service-ribbon</name>

   <description>service-ribbon-description</description>

   <parent>

      <groupId>org.springframework.boot</groupId>

      <artifactId>spring-boot-starter-parent</artifactId>

      <version>1.5.13.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>Edgware.SR3</spring-cloud.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.cloud</groupId>

         <artifactId>spring-cloud-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>

application.yml如下

spring:

  application:

    name: service-ribbon

server:

  port: 8764

eureka:

  client:

    service-url:

      defaultZone: http://localhost:8761/eureka/

项目启动类修改如下

@EnableDiscoveryClient

@SpringBootApplication

public class ServiceRibbonApplication {

   public static void main(String[] args) {

      SpringApplication.run(ServiceRibbonApplication.class, args);

   }

   @Bean

   @LoadBalanced

   RestTemplate restTemplate(){

      return new RestTemplate();

   }

}

通过@EurekaDiscoveryClient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。

新建测试service

@Service

public class HelloService {

    @Autowired

    RestTemplate restTemplate;

    public String hiService(String name) {

        return restTemplate.getForObject("http://eureka-client/hello?name=" + name, String.class);

    }

}

新建测试controller

@RestController

public class HelloController {

    @Autowired

    HelloService helloService;

    @RequestMapping("/hi")

    public String hi(@RequestParam String name) {

        return helloService.hiService(name);

    }

}

浏览器访问

http://localhost:8764/hi?name=test
可看到以下效果

巴特西

SpringCloud-服务的消费者(rest+ribbon)