关于Spring Cloud Open Feign的介绍可以参考这两篇博客
OpenFeign服务接口调用
使用Feign作为服务消费者
本博客参考gitee开源项目代码，结合自己的理解，记录下微服务场景下的使用。Talk is cheap. Show me the code！

一、项目结构

这里使用eureka作为注册中心,，person和equipment两个web服务作为业务中台，本例中会使用postman调用person服务，person服务中调用equipment服务。

registry -- 注册中心(当前采用eureka)
person -- 人员服务
 person-api -- 人员相关api提供, 包括 req, resp, service 等
 person-biz -- 人员相关服务接口具体实现, 依赖person-api
 person-provider -- 人员相关微服务启动类, 依赖person-biz
equipment -- 设备服务
 equipment-api -- 设备相关api提供, 包括 req, resp, service 等
 equipment-biz -- 设备相关服务接口具体实现, 依赖equipment-api
 equipment-provider -- 设备相关微服务启动类, 依赖equipment-biz

源码下载地址，欢迎star！
springboot-openfeign

二、registry – 注册中心(当前采用eureka)

1、application.yml

server:
  port: 8001  # 该服务端口

eureka:
  instance:
    hostname: registry  # eureka的实例名称
  client:
    registerWithEureka: false  # false表示当前项目不以客户端注册到服务中心(因为该项目本身就是注册中心)
    fetchRegistry: false  # false表示当前项目不需要从注册中心拉取服务配置(因为该项目本身就是注册中心)
    serviceUrl:
      defaultZone: http://localhost:8001/eureka/

spring:
  application:
    name: server-registy  # 当前项目的实例名称(很重要)

2、核心pom.xml

<!-- 引入eureka-server依赖  -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
            <version>2.1.3.RELEASE</version>
        </dependency>

        <!-- gson -->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.6.2</version>
        </dependency>

3、主启动类RegistryApplication

@SpringBootApplication
@EnableEurekaServer
public class RegistryApplication {
    public static void main(String[] args) {
        SpringApplication.run(RegistryApplication.class, args);
    }
}

三、person – 人员服务

1、application.yml

server:
  port: 8002

spring:
  application:
    name: person-provider

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8001/eureka/

feign:
　httpclient:
　　enabled: true

2、核心pom.xml

cloud-person-provider

<dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            <version>2.2.1.RELEASE</version>
</dependency>

cloud-person-biz

        <!-- 使用web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.2.1.RELEASE</version>
        </dependency>

        <!-- person-api -->
        <dependency>
            <groupId>tca</groupId>
            <artifactId>cloud-person-api</artifactId>
            <version>1.0.0</version>
        </dependency>

        <!-- equipment-api -->
        <dependency>
            <groupId>tca</groupId>
            <artifactId>cloud-equipment-api</artifactId>
            <version>1.0.0</version>
        </dependency>

cloud-person-api

        <!-- openFeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>2.2.1.RELEASE</version>
        </dependency>

3、PersonFeign和PersonController

@FeignClient(value = "person-provider")
public interface PersonFeign {
    /**
     * 根据id获取人员
     * @param personReq
     * @return
     */
    @PostMapping("/person/get")
    PersonResp get(PersonReq personReq);
}

@RestController
@RequestMapping(value = "/person")
@Slf4j
public class PersonController {

    @Autowired
    private EquipmentFeign equipmentFeign;

    /**
     * 获取人员
     * @param personReq
     * @return
     */
    @PostMapping("/get")
    public PersonResp get(@Validated @RequestBody PersonReq personReq) {
        PersonResp personResp = new PersonResp();
        personResp.setId(personReq.getId());
        personResp.setAge(30);
        personResp.setName("Messi");

        EquipmentReq equipmentReq = new EquipmentReq();
        equipmentReq.setId(personReq.getId());
        EquipmentResp equipmentResp = equipmentFeign.get(equipmentReq);
        log.info("equipmentResp = {}", equipmentResp);
        return personResp;
    }
}

4、项目结构

四、equipment – 设备服务

1、application.yml

server:
  port: 8003

spring:
  application:
    name: equipment-provider

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8001/eureka/

2、核心pom.xml

cloud-equipment-api

        <!-- openFeign -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>2.2.1.RELEASE</version>
        </dependency>

cloud-equipment-biz

<!-- 使用web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.2.1.RELEASE</version>
        </dependency>

        <!-- equipment-api -->
        <dependency>
            <groupId>tca</groupId>
            <artifactId>cloud-equipment-api</artifactId>
            <version>1.0.0</version>
        </dependency>

        <!-- person-api -->
        <dependency>
            <groupId>tca</groupId>
            <artifactId>cloud-person-api</artifactId>
            <version>1.0.0</version>
        </dependency>

cloud-equipment-provider

       <dependency>
            <groupId>tca</groupId>
            <artifactId>cloud-equipment-biz</artifactId>
            <version>1.0.0</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            <version>2.2.1.RELEASE</version>
        </dependency>

3、EquipmentFeign和EquipmentController

@FeignClient(value = "equipment-provider")
public interface EquipmentFeign {

    /**
     * 根据id获取人员
     * @param equipmentReq
     * @return
     */
    @PostMapping("/equipment/get")
    EquipmentResp get(EquipmentReq equipmentReq);
}

@RestController
@RequestMapping(value = "/equipment")
@Slf4j
public class EquipmentController {

    @Autowired
    private PersonFeign personFeign;

    /**
     * 获取人员
     * @param equipmentReq
     * @return
     */
    @PostMapping("/get")
    public EquipmentResp get(@Validated @RequestBody EquipmentReq equipmentReq) {
        EquipmentResp equipmentResp = new EquipmentResp();
        equipmentResp.setId(equipmentReq.getId());
        equipmentResp.setName("平板设备");
        return equipmentResp;
    }
}

4、项目结构

五、测试

分别启动这三个服务，

利用postman访问localhost:8002/person/get，其中body中id传不同参数进行测试


可以发现能够通过openfeign在微服务之间进行接口调用！