(1-2)SpringCloud:服务的消费者rest+ribbon

　　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);
    }

}

　　七、测试一下看是否成功。

　　1.先启动Eureka注册中心

　　2.再运行ServiceApplication.java

　　3.最后运行ribbon，在浏览器输入http://localhost:8764/hello?name=wali

证明调用成功!!!

https://gitee.com/huayicompany/springcloud-learn/tree/master/lesson1

参考：

[1] 博客，http://blog.csdn.net/forezp/article/details/70148833

[2] 博客，http://www.cnblogs.com/skyblog/p/5133752.html

[3] 《SpringCloud微服务实战》，电子工业出版社，翟永超