Spring Cloud基础教程（四）：服务消费（Feign）

末蓝、 2022-05-24 03:55 176阅读 0赞

上一篇博客中讲解了[服务消费（Ribbon）][Ribbon]的使用，本篇博客讲解下服务消费（Feign）的使用。

# 一、准备 #

使用这篇博客[服务生产者的创建][Link 1]中创建的Eureka-Server和Service-Producer。

# 二、创建Consumer-Feign工程 #

工程gradle依赖为

dependencies {
    	compile('org.springframework.boot:spring-boot-starter-web')
    	compile('org.springframework.cloud:spring-cloud-starter-feign:1.4.4.RELEASE')
    	compile('org.springframework.cloud:spring-cloud-starter-eureka:1.4.4.RELEASE')
    	compile('org.springframework.cloud:spring-cloud-starter-ribbon:1.4.4.RELEASE')
    	testCompile('org.springframework.boot:spring-boot-starter-test')
    }

在启动类上添加@EnableFeignClients和@EnableDiscoveryClient注解

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.openfeign.EnableFeignClients;
    
    @EnableDiscoveryClient
    @SpringBootApplication
    @EnableFeignClients
    public class ConsumerFeignApplication
    {
    
    	public static void main(String[] args) {
    		SpringApplication.run(ConsumerFeignApplication.class, args);
    	}
    }

创建ConsumerService接口，调用生产者的服务，@FeignClient指定要调用的生产者的服务器名称，对应的接口指定调用的URL地址。

import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    
    /**
     * Created by wzj on 2018/5/20.
     */
    @FeignClient("service-producer")
    public interface ConsumerService
    {
        @RequestMapping(value = "/client",method = RequestMethod.GET)
        String client();
    }

创建Controller，调用上面创建的接口，通过Spring Cloud Feign来实现服务调用的方式更加简单了，通过@FeignClient定义的接口来统一的生命我们需要依赖的微服务接口。而在具体使用的时候就跟调用本地方法一点的进行调用即可。由于Feign是基于Ribbon实现的，所以它自带了客户端负载均衡功能，也可以通过Ribbon的IRule进行策略扩展。

import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.client.RestTemplate;
    
    /**
     * Created by wzj on 2018/5/19.
     */
    @RestController
    public class ConsumerController
    {
        /**
         * 注入
         */
        @Autowired
        private ConsumerService consumerService;
    
        @RequestMapping("/consumer")
        public String client()
        {
            return consumerService.client();
        }
    }

# 三、测试 #

动Eureka-Server、Service-Producer-A、Service-Producer-B和Consumer-feign，访问[http://127.0.0.1:10001/][http_127.0.0.1_10001]，发现都已注册到了注册中心。

![20180520112225280][]

通过feign调用消费者的Rest接口，[http://127.0.0.1:10007/consumer][http_127.0.0.1_10007_consumer]，发现负载到了Producer-A

![20180520112335672][]

关闭浏览器，再次访问[http://127.0.0.1:10007/consumer][http_127.0.0.1_10007_consumer]，发现负载到了，发现负载到了Producer-B

![20180520112426515][]

源码Github地址：[https://github.com/HelloKittyNII/SpringCloud/tree/master/SpringCloudFramework][https_github.com_HelloKittyNII_SpringCloud_tree_master_SpringCloudFramework]

[Ribbon]: https://blog.csdn.net/u010889616/article/details/80373613
[Link 1]: https://blog.csdn.net/u010889616/article/details/80373406
[http_127.0.0.1_10001]: http://127.0.0.1:10001/
[20180520112225280]: /images/20220524/467761931c6d4ca4a33168722a41c688.png
[http_127.0.0.1_10007_consumer]: http://127.0.0.1:10007/consumer
[20180520112335672]: /images/20220524/53f681916450457e8bc3f28ca9c29da0.png
[20180520112426515]: /images/20220524/9361f2d359184638a5a7fcb8fc669bbb.png
[https_github.com_HelloKittyNII_SpringCloud_tree_master_SpringCloudFramework]: https://github.com/HelloKittyNII/SpringCloud/tree/master/SpringCloudFramework