Feign

声明式的webservice注解，面向接口开发。feign集成了ribbon 使用过程，创建1个接口，在上面增加注解即可

Feign配置过程

1. 在common-apis项目中增加com.xyz.service.DeptService接口，采用接口+注解的方式配置feign客户端调用(需要在pom中增加对feign的支持)

   package com.xyz.service;
   
   import com.xyz.entity.Dept;
   import org.springframework.cloud.openfeign.FeignClient;
   import org.springframework.stereotype.Service;
   import org.springframework.web.bind.annotation.RequestMapping;
   
   /**
    * @author xyz
    * @date 2020年2月24日
    * @decription feign调用的客户端接口
    */
   @FeignClient(value = "microservice-provider")
   @Service
   public interface DeptService {
   
       @RequestMapping("/provider/list")
       Dept list();
   
   }
   
   

2. 创建consumerfeign-9101 module，创建pom文件

   <?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">
       <parent>
           <artifactId>XyzSpringCloud-Finchley</artifactId>
           <groupId>com.xyz</groupId>
           <version>1.0-SNAPSHOT</version>
       </parent>
       <modelVersion>4.0.0</modelVersion>
   
       <artifactId>ConsumerFeign-9101</artifactId>
   
       <dependencies>
   
           <dependency>
               <groupId>com.xyz</groupId>
               <artifactId>Common-APIs</artifactId>
               <version>${project.version}</version>
           </dependency>
   
           <!--eureka client-->
           <dependency>
               <groupId>org.springframework.cloud</groupId>
               <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
           </dependency>
   
           <!--feign-->
           <dependency>
               <groupId>org.springframework.cloud</groupId>
               <artifactId>spring-cloud-starter-openfeign</artifactId>
           </dependency>
   
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-actuator</artifactId>
           </dependency>
   
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-web</artifactId>
           </dependency>
   
           <dependency>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-devtools</artifactId>
           </dependency>
   
       </dependencies>
   
   </project>
   

3. consumerfeign-9101创建application.yml文件

   server:
       port: 9101
   
   
   eureka:
     client:
       service-url:
         defaultZone: http://server7001:7001/eureka/,http://server7002:7002/eureka/,http://server7003:7003/eureka/
     instance:
       instance-id: microserviceconsumerfeign9101
       prefer-ip-address: true
   
   
   spring:
     application:
       name: microservice-consumerfeign
   
   #解决eureka控制台中的Info页面错误问题
   info:
     app.name: com.xyz.microservice
     build.artifactId: $project.artifactId$ #使用maven内置变量project.artifactId和project.version完成对变量的赋值
     build.version: $project.version$
   

4. consumerfeign-9101 中增加com.xyz.controller.ConsumerFeign方法，实现对feign客户端的调用

   package com.xyz.controller;
   
   
   import com.xyz.entity.Dept;
   import com.xyz.service.DeptService;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.web.bind.annotation.RequestMapping;
   import org.springframework.web.bind.annotation.RestController;
   
   
   /**
    * @author xyz
    * @date 2020年2月24日
    * @description feign调用的controller层
    */
   @RestController
   public class ConsumerFeign {
   
       @Autowired
       private DeptService deptService;
   
       @RequestMapping("/consumerfeign/list")
       public Dept list() {
           return deptService.list();
       }
   }
   
   

5. consumerfeign-9101主启动类开启对feign的支持

   package com.xyz;
   
   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
   /**
    * 开启client端对feign的调用
    */
   @EnableFeignClients
   public class ConsumerFeign9101 {
   
       public static void main(String[] args) {
           SpringApplication.run(ConsumerFeign9101.class, args);
       }
   }
   
   

6. 访问地址 http://localhost:9101/consumerfeign/list

7. feign集成了ribbon，因此也可以修改默认的算法，代码同ribbon，在 com.xyz.bean.Config类中引用别的算法

代码示例-github

参考

• Spring Cloud构建微服务架构：服务消费（Feign）【Dalston版】-程序猿DD