SpringCloud从入门到精通教程（四）- 服务消费者，实现方式二(feign)

逃离我推掉我的手 2023-02-26 02:06 29阅读 0赞

# 需求背景 #

> 服务消费者，实现方式二：feign（推荐此方式）

# Feign是什么？ #

Feign是一个声明式的web service客户端，它使得编写web service客户端更为容易。创建接口，为接口添加注解，即可使用Feign。Feign可以使用Feign注解或者JAX-RS注解，还支持热插拔的编码器和解码器。

Spring Cloud为Feign添加了Spring MVC的注解支持，并整合了Ribbon和Eureka来为使用Feign时提供负载均衡。使用@EnableFeignClients即可开启Feign。

简而言之：

*  Feign 采用的是基于接口的注解
 *  Feign 整合了ribbon，具有负载均衡的能力
 *  整合了Hystrix，具有熔断的能力

# Tips技术点 #

1.** **@EnableFeignClients注解

*  开启Feign

2. 引入openfeign组件包

# 代码演示 #

## 1. 项目目录结构 ##

**![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw_size_16_color_FFFFFF_t_70][]**

## 2. pom.xml依赖组件 ##

<?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>
    
    	<artifactId>microservice-consumer-movie-feign</artifactId>
    	<packaging>jar</packaging>
    
    	<parent>
    		<groupId>com.minbo.cloud</groupId>
    		<artifactId>spring-cloud-microservice-study</artifactId>
    		<version>0.0.1-SNAPSHOT</version>
    	</parent>
    
    	<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-openfeign</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-actuator</artifactId>
    		</dependency>
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-zipkin</artifactId>
    		</dependency>
    	</dependencies>
    </project>

## 3. application.yml配置文件 ##

server:
       port: 8020
    spring:
       application:
          name: microservice-consumer-movie-feign
    eureka:
       client:
          serviceUrl:
             defaultZone: http://localhost:8761/eureka/
       instance:
          preferIpAddress: true

## 4. 消费接口类 ##

MyFeignClient.java

package com.minbo.cloud.study.feign;
    
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RequestParam;
    
    /**
     * 使用@FeignClient("microservice-provider-user")注解绑定microservice-provider-user服务，还可以使用url参数指定一个URL。
     */
    @FeignClient(name = "microservice-provider-user")
    public interface MyFeignClient {
    
    	//定义代码调用对方服务的"/hi"接口
    	@RequestMapping(value = "/hi", method = RequestMethod.GET)
    	String sayHiFromClientOne(@RequestParam(value = "name") String name);
    
    }

FeignController.java

package com.minbo.cloud.study.controller;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    import com.minbo.cloud.study.feign.MyFeignClient;
    import com.minbo.cloud.study.feign.MyFeignClient2;
    
    @RestController
    public class FeignController {
    
    	@Autowired
    	private MyFeignClient feignClient;
    
    	@GetMapping(value = "/hi")
    	public String sayHi(@RequestParam String name) {
    		String result = this.feignClient.sayHiFromClientOne(name);
    		return result;
    	}
    }

## 5. 启动类 ##

package com.minbo.cloud.study;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.cloud.openfeign.EnableFeignClients;
    
    /**
     * Feign是一个声明式的web service客户端，它使得编写web service客户端更为容易。
     * 创建接口，为接口添加注解，即可使用Feign。
     * Feign可以使用Feign注解或者JAX-RS注解，还支持热插拔的编码器和解码器。
     * Spring Cloud为Feign添加了Spring MVC的注解支持，并整合了Ribbon和Eureka来为使用Feign时提供负载均衡。
     * 使用@EnableFeignClients开启Feign
     * 
     * 简而言之：
     * a. Feign 采用的是基于接口的注解
     * b. Feign 整合了ribbon，具有负载均衡的能力
     * c. 整合了Hystrix，具有熔断的能力
     */
    @SpringBootApplication
    @EnableEurekaClient
    @EnableDiscoveryClient
    @EnableFeignClients
    public class MovieFeignApplication {
    	
    	public static void main(String[] args) {
    		SpringApplication.run(MovieFeignApplication.class, args);
    	}
    	
    }

## 6. 是否消费接口成功 ##

启动服务后，可以查看Eureka界面注册信息

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw_size_16_color_FFFFFF_t_70 1][]

访问本服务接口：[http://localhost:8020/hi?name=minbo][http_localhost_8020_hi_name_minbo]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw_size_16_color_FFFFFF_t_70 2][]

表示已经成功消费了服务提供者的接口（服务提供者监听端口是8000）

# 完整源码下载 #

我的[Github源码地址：][Github]

[https://github.com/hemin1003/spring-cloud-study/tree/master/spring-cloud-greenwich/microservice-consumer-movie-feign][https_github.com_hemin1003_spring-cloud-study_tree_master_spring-cloud-greenwich_microservice-consumer-movie-feign]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw_size_16_color_FFFFFF_t_70 3][]

# 上一章教程 #

[SpringCloud从入门到精通教程（三）- 服务消费者，实现方式一(ribbon)][SpringCloud_- _ribbon]

# 该系列教程 #

[SpringCloud从入门到精通教程][SpringCloud]

# 我的专栏 #

*  [SpringBoot系列专栏][SpringBoot]
 *  [SpringCloud系列专栏][SpringCloud]
 *  [高可用高并发实战][Link 1][专栏][Link 2]
 *  [微服务架构实战][Link 3]
 *  [DevOps实战专栏][DevOps]
 *  [程序化广告实战专栏][Link 2]

至此，全部介绍就结束了

\-------------------------------

[我的CSDN主页][CSDN]

[关于我][Link 4]（个人域名）

[我的开源项目集Github][Github 1]

期望和大家***一起学习，一起成长***，共勉，O(∩\_∩)O谢谢

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不讲虚的，只做实干家

Talk is cheap，show me the code

![20180411181545874][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw_size_16_color_FFFFFF_t_70]: /images/20230209/a6e4779550c64582b00ca68bf275c4f3.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw_size_16_color_FFFFFF_t_70 1]: /images/20230209/df94943125334c1fb7b8a823f6ee81ff.png
[http_localhost_8020_hi_name_minbo]: http://localhost:8010/hi?name=minbo
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20200713171129882.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw==,size_16,color_FFFFFF,t_70
[Github]: https://github.com/hemin1003/spring-cloud-study/tree/master/spring-cloud-greenwich
[https_github.com_hemin1003_spring-cloud-study_tree_master_spring-cloud-greenwich_microservice-consumer-movie-feign]: https://github.com/hemin1003/spring-cloud-study/tree/master/spring-cloud-greenwich/microservice-consumer-movie-feign
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20200713183031621.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hlbWluMTAwMw==,size_16,color_FFFFFF,t_70
[SpringCloud_- _ribbon]: https://hemin.blog.csdn.net/article/details/107320219
[SpringCloud]: https://blog.csdn.net/hemin1003/category_9293625.html
[SpringBoot]: https://blog.csdn.net/hemin1003/article/category/9291077
[Link 1]: https://blog.csdn.net/hemin1003/article/category/9292134
[Link 2]: https://blog.csdn.net/hemin1003/article/category/9290971
[Link 3]: https://blog.csdn.net/hemin1003/article/category/9292162
[DevOps]: https://blog.csdn.net/hemin1003/article/category/9292130
[CSDN]: https://blog.csdn.net/hemin1003
[Link 4]: http://heminit.com/about/
[Github 1]: https://github.com/hemin1003
[20180411181545874]: https://img-blog.csdn.net/20180411181545874