SpringCloud系列之声明式服务调用NetflixFeign

Z时代
2024-01-10
分类：综合

在上一章的学习中，我们知道了微服务的基本概念，知道怎么基于Ribbon+restTemplate的方式实现服务调用，接着上篇博客，我们学习怎么基于Feign实现服务调用，请先学习上篇博客，然后再学习本篇博客

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。

环境准备：

JDK 1.8

SpringBoot2.2.3

SpringCloud(Hoxton.SR6)

Maven 3.2+

开发工具
- IntelliJ IDEA
- smartGit

创建一个SpringBoot Initialize项目，详情可以参考我之前博客：SpringBoot系列之快速创建项目教程

port: 8083 spring: application: name: feign-service-consumer eureka: client: service-url: defaultZone: http://localhost:8761/eureka/ healthcheck: enabled: false instance: status-page-url-path: http://localhost:8761/actuator/info health-check-url-path: http://localhost:8761/actuator//health prefer-ip-address: true instance-id: feign-service-consumer8083

@FeignClient指定服务名称，@RequestMapping指定要调用的接口

package com.example.springcloud.client.service;
import com.example.springcloud.client.bean.User;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
/**
 * <pre>
 *  UserService
 * </pre>
 *
 * <pre>
 * @author mazq
 * 修改记录
 *    修改后版本:     修改人：  修改日期: 2020/07/28 13:09  修改内容:
 * </pre>
 */
@FeignClient(value = "EUREKA-SERVICE-PROVIDER")
@Service
public interface UserService {
    @RequestMapping(value = "/api/users/{username}",method = RequestMethod.GET)
    User findGithubUser(@PathVariable("username")String username);
}

加上@EnableEurekaClient，@EnableFeignClients，写个接口进行测试

package com.example.springcloud.client;
import com.example.springcloud.client.bean.User;
import com.example.springcloud.client.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.scheduling.annotation.Async;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
@RestController
public class SpringcloudFeignClientApplication {
    @Autowired
    UserService userService;
    public static void main(String[] args) {
        SpringApplication.run(SpringcloudFeignClientApplication.class, args);
    }
    @GetMapping("/findUser/{username}")
    public User index(@PathVariable("username")String username){
        return userService.findGithubUser(username);
    }
}