使用Feign作为服务消费者

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已于 2023-03-26 23:47:49 修改

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分类专栏： SpringCloud 文章标签： feign springcloud

于 2021-03-06 16:16:07 首次发布

本文链接：https://blog.youkuaiyun.com/jike11231/article/details/114439397

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Ribbon是一个基于Http和TCP的负载均衡工具，而Feign（音：菲恩）是一个声明式的伪Http客户端，它比Ribbon更加的优雅。Feign使用的是接口的方式。Feign默认集成了Ribbon，并和Eureka结合，默认实现了负载均衡的效果。

一、Feign使用介绍

1.1 导入feign依赖

   <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>

1.2 编写application.yml配置文件

#指明注册中心的位置
eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
#当前项目部署的端口
server:
  port: 8765
#当前项目的名称
spring:
  application:
    name: service-feign

1.3 编写启动类

@EnableFeignClients注解是开启feign负载均衡工具。

package com.safesoft.feign;
 
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;
 
@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
@EnableFeignClients
public class ApplicationFeign {
    public static void main(String[] args) {
        SpringApplication.run(ApplicationFeign.class, args);
    }
}

1.4 编写服务接口

package com.safesoft.feign.service;
 
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
 
@FeignClient(value = "SERVICE-CLIENT")
public interface HelloService {
 
    /**
     * 从SERVICE-CLIENT服务器的/hi接口获取JSON数据
     * @param name
     * @return
     */
    @RequestMapping("/hi")
    String obtainOtherServerJsonData(@RequestParam(value = "name") String name);
}

1.5 编写Controller

package com.safesoft.feign.web;
 
import com.safesoft.feign.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
 
@RestController
public class HelloController {
 
    /**
     * 因为HelloService仅仅使用了@FeiginClient注解
     * 没有使用@Bean类型的注解，比如@Service @Component等
     * 所以编译器会警告，其实可以忽视它
     */
    @Autowired
    private HelloService helloService;
 
    @RequestMapping("/sayHello")
    public String sayHello(String name) {
        return helloService.obtainOtherServerJsonData(name);
    }
}

1.6 启动Feign服务器

在浏览器上输入http://localhost:8765/hello?name=pc，尝试从8765端口获取JSON数据。此请求会被Feign服务器负载均衡到部署在8762端口与8763端口的服务器上。
第一次刷新结果如下：
在这里插入图片描述
第二次刷新结果如下：

1.7 源码下载地址

spring-cloud-01

二、项目中实际使用

1 admin服务，端口号32032，admin主启动类要加@EnableFeignClients
1.1CmsUserGroupClient

import com.xxx.cms.service.api.api.ICmsUserGroupController;
@FeignClient(value = "${feign.cms.service.name}", contextId = "CmsUserGroupClient")
//@FeignClient(value = "mth-cms-service", contextId = "CmsUserGroupClient")
//@FeignClient(url = "127.0.0.1:32031", value = "mth-equity-service", contextId = "CmsUserGroupClient ")
public interface CmsUserGroupClient extends ICmsUserGroupController {

}

1.2 bootstrap.yml

server:
  port: 32032
  servlet:
    context-path: /cms-admin
spring:
  application:
    name: mth-cms-admin
# feign服务名统一配置
feign:
  cms:
    service:
      name: mth-cms-service

1.3 CmsUserGroupController

import com.xxx.cms.admin.service.CmsUserGroupService;
@RestController
public class CmsUserGroupController {

    @Autowired
    private CmsUserGroupService cmsUserGroupService;

    /**
     * 分页查询用户组列表，支持模糊搜索
     */
    @PostMapping("/user/group/page")
    @ApiOperation("分页查询用户组列表 用户组类型:0-静态 1-动态")
    MthResponse<PagingResult<CmsUserGroupResp>> getUserGroupPage(@RequestBody(required = false) CmsUserGroupReq cmsUserGroupReq) throws Exception {
        return cmsUserGroupService.getUserGroupPage(cmsUserGroupReq);
    }
}

1.4 CmsUserGroupService及CmsUserGroupServiceImpl

public interface CmsUserGroupService {
    /**
     * 分页查询用户组列表
     * @param req
     * @return PagingResult<CmsUserGroupResp>
     * @throws Exception
    */
    MthResponse<PagingResult<CmsUserGroupResp>> getUserGroupPage(CmsUserGroupReq req) throws Exception;
}

import com.xxx.cms.admin.service.CmsUserGroupService;
import com.xxx.cms.admin.client.cms.CmsUserGroupClient;
@Slf4j
@Service
public class CmsUserGroupServiceImpl implements CmsUserGroupService {
    @Resource
    private CmsUserGroupClient cmsUserGroupClient;

    /**
     * 分页查询用户组列表
     */
    @Override
    public MthResponse<PagingResult<CmsUserGroupResp>> getUserGroupPage(CmsUserGroupReq req) throws Exception {
        MthResponse<PagingResult<CmsUserGroupResp>> resp = cmsUserGroupClient.getUserGroupPage(req);
        if(resp.fail()){
            ExceptionUtils.create(resp);
        }
        return resp;
    }
}

2 service服务，包括service-api和service-web服务，端口号32031，service-web主启动类要加@EnableFeignClients
2.1service-api服务的ICmsUserGroupController

public interface ICmsUserGroupController {

    /**
     * 分页查询用户组列表
     * @param req
     * @return PagingResult<CmsUserGroupResp>
     * @throws CommonException
    */
    @PostMapping("/user/group/page")
    @ApiOperation("分页查询用户组列表")
    MthResponse<PagingResult<CmsUserGroupResp>> getUserGroupPage(@RequestBody(required = false) @Param("req") CmsUserGroupReq req) throws CommonException;
}

2.2 service-web服务的bootstrap.yml

server:
  port: 32031
spring:
  application:
    name: mth-cms-service
  profiles:
    active: local
  cloud:
    loadbalancer:
      ribbon:
        enabled: false
fast:
  common:
    web:
      logging:
        path: /apps/logs
        level: INFO

# feign服务名统一配置
feign:
  config:
    service:
      name: mth-config-service

2.3 service-web服务的CmsUserGroupService及CmsUserGroupServiceImpl

import com.xxx.cms.service.api.entity.CmsUserGroup;
import com.baomidou.mybatisplus.extension.service.IService;

public interface CmsUserGroupService extends IService<CmsUserGroup> {

    /**
     * 分页查询用户组列表
     * @param req
     * @return PagingResult<CmsUserGroupResp>
     * @throws CommonException
    */
    PagingResult<CmsUserGroupResp> getUserGroupPage(CmsUserGroupReq req) throws CommonException;
}

import com.xxx.cms.service.web.service.CmsUserGroupService;

@Service
public class CmsUserGroupServiceImpl extends ServiceImpl<CmsUserGroupMapper, CmsUserGroup>
    implements CmsUserGroupService {

    /**
     * 分页查询用户组列表
     * @param req
     * @return PagingResult<CmsUserGroupResp>
     * @throws CommonException
     */
     @Override
    public PagingResult<CmsUserGroupResp> getUserGroupPage(CmsUserGroupReq req) {
        IPage<CmsUserGroupResp> page = new Page<>(req.getPage(),req.getPageSize());
        Page<CmsUserGroupResp> tasks = baseMapper.getUserGroupPage(page,req);
        return PagingUtils.getPagingResult(tasks);
    }
}