(1-2)SpringCloud:服务的消费者rest+ribbon

2022-09-03 20:33:57

　　服务发现的任务是由Eureka客户端完成，而服务的消费任务由Ribbon完成。Ribbon是一个基于HTTP和TCP的客户端负载据衡器，它可以通过客户端中配置ribbonServerList服务端列表去轮询访问以达到负载均衡的作用。当Ribbon与Eureka联合使用时，Ribbon的服务实例清单RibbonServerList会被DiscoveryEnableNIWSServerList重写，扩展成从Eureka注册中心获取服务端列表。这里不再对Ribbon做过多的介绍。后面会详细的介绍和分析

　　下面会通过一个示例来看看Eurka的服务治理体系下如何实现服务的发现与消费。

　　一、创建一个独立的maven项目

　　二、添加相关的maven依赖

<parent>

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

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

    <version>1.5.2.RELEASE</version>

    <relativePath/> <!-- lookup parent from repository -->

</parent>

<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>

<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>

　　三、application.yml配置文件

eureka:

  client:

    serviceUrl:

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

server:

  port: 8764

spring:

  application:

    name: service-ribbon

　　四、写启动类。

package org.hope;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;

import org.springframework.context.annotation.Bean;

import org.springframework.web.client.RestTemplate;

@SpringBootApplication

@EnableDiscoveryClient

public class ServiceRibbonApplication {

    public static void main(String[] args) {

        SpringApplication.run(ServiceRibbonApplication.class, args);

    }

    @Bean

    RestTemplate restTemplate() {

        return new RestTemplate();

    }

}

　　五、写service来调用服务提供者

package org.hope.service;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import org.springframework.web.client.RestTemplate;

@Service

public class HelloService {

    @Autowired

    RestTemplate restTemplate;

    public String hiService(String name) {

        return restTemplate.getForObject("http://localhost:8762/hello?name=" + name, String.class);
　　　　　//SERVICE-HI是服务提供者的实例名称，这里用这种形式调用服务也是可以的。
　　　　 return restTemplate.getForObject("http://SERVICE-HI/hello?name=" + name, String.class);

} }

　　六、写一个controller来调用service

package org.hope.web;

import org.hope.service.HelloService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.web.bind.annotation.RestController;

@RestController

public class HelloControler {

    @Autowired

    HelloService helloService;

    @RequestMapping(value = "/hello")

    public String hi(@RequestParam String name){

        return helloService.hiService(name);

    }

}