springCloud Finchley 微服务架构从入门到精通【四】服务消费者(feign)

桃扇骨 2023-10-17 21:11 34阅读 0赞

上篇文章我们写了**service-user**服务提供者，并使用**ribbon**的方式去调用，本次，我们依然使用上一章节中的**service-user**作为服务提供者，改为使用**feign**去消费这个微服务

**feign**客户端和**ribbon** 类似，同样实现了客户端的负载均衡，与ribbon不同的是，feign的调用与本地接口的调用更加类似，并且更加便捷、更加优雅，传入参数较多时得以体现，当然，在实际项目中，两者可能都会用到，下面来写一下feign的实现  
\#\#一、创建一个服务消费者 feign \#\#  
\#\#\#1、创建项目\#\#\#

![这里写图片描述][70]

**选择Feign 和 Eureka Server点击完成**

![这里写图片描述][70 1]

**pom.xml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.mayi.springcloud</groupId>
    	<artifactId>bussnessservice-user-client-feign</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>jar</packaging>
    
    	<name>bussnessservice-user-client-feign</name>
    	<description>用户中心服务调用者feign</description>
    
    	<parent>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-parent</artifactId>
    		<version>2.0.1.RELEASE</version>
    		<relativePath/> 
    	</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>Finchley.M9</spring-cloud.version>
    	</properties>
    
    	<dependencies>
    		<dependency>
    			<groupId>org.springframework.cloud</groupId>
    			<artifactId>spring-cloud-starter-netflix-eureka-server</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-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>
    
    	<repositories>
    		<repository>
    			<id>spring-milestones</id>
    			<name>Spring Milestones</name>
    			<url>https://repo.spring.io/milestone</url>
    			<snapshots>
    				<enabled>false</enabled>
    			</snapshots>
    		</repository>
    	</repositories>
    
    
    </project>

\#\#\#2、修改配置\#\#\#

**bootstrap.yml**

spring:
      application:
        name: service-user-client-feign
    server:
      port: 9001

在启动类添加\*\*@EnableFeignClients\*\*以启动feign客户端

package com.mayi.springcloud;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
    import org.springframework.cloud.openfeign.EnableFeignClients;
    
    @SpringBootApplication
    @EnableEurekaClient
    @EnableFeignClients
    public class BussnessserviceUserClientFeignApplication {
        
    
    	public static void main(String[] args) {
        
    		SpringApplication.run(BussnessserviceUserClientFeignApplication.class, args);
    	}
    }

\#\#\#3、具体实现代码\#\#\#

新建两个包：api 和 client 并创建相应的实现类

![这里写图片描述][70 2]

说明： **UserFeignClien**t 是**feign**接口， **UserFeignApi** 是**feign接口的调用者**

UserFeignClient 代码如下：

package com.mayi.springcloud.client;
    
    import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.GetMapping;
    
    @FeignClient(name="service-user")
    public interface UserFeignClient {
        
    	
    	@GetMapping("/listUsers")
    	public String listUsers();
    	
    }

解释：

1.  @FeignClient(name=“service-user”) 标明**feign**调用的**微服务名称**
2.  @GetMapping(“/listUsers”) 对应**service-user**微服务中的**URL**

UserFeignApi 代码如下：

package com.mayi.springcloud.api;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import com.mayi.springcloud.client.UserFeignClient;
    
    @RestController
    public class UserFeignApi {
        
    	
    	@Autowired
    	private UserFeignClient userFeignClient;
    	
    	
    	@GetMapping("/listUsersByFeign")
    	public String ListUsers(){
        
    		String users = this.userFeignClient.listUsers();
    		return users;
    	}
    	
    }

解释：  
将刚才定义的userFeignClient注入，并当成普通的接口调用即可

\#\#\#4、测试\#\#\#

启动两个service-user服务：端口分别为 8801 和 8802

![这里写图片描述][70 3]

访问：http://localhost:9001/listUsersByFeign

结果页面如下：

![这里写图片描述][70 4]

至此，feign的整合已完成，

下篇文章，我们将要介绍**配置中心**的使用

**接下来，我会依次更新文章，直至整个架构完成，如有兴趣的朋友关注作者 或 加我微信 拉你进入spring cloud社区群**

![这里写图片描述][70 5]  
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![这里写图片描述][70 6]

**本公众号将要按照JAVA高级软件架构师实战培训的路线发布一期完整的架构文章，难度由浅入深，适合有一定开发基础想转架构和正在做初级架构开发的人员学习**

[70]: https://img-blog.csdn.net/20180428105734808?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYmxvZw==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70
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[70 6]: https://img-blog.csdn.net/20180428105951997?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3djYmxvZw==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70