一.简介
SpringCloud是基于Restful的远程调用框架，引入Ribbon负载均衡组件后还需要客户端使用RestTemplate调用远程接口，操作起来还显得繁琐。SpringCloud提供了远程接口映射，将远程Restful服务映射为远程接口，消费端注入远程接口即可实现方法调用。
二.流程
1.新建远程接口映射模块service-api，并引入Feign接口映射依赖
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
</dependencies>
2.编写接口映射接口
package com.vincent.service;
import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
@FeignClient("SERVICE-USER")
@RequestMapping("/service-user")
public interface IUserService {
@GetMapping("/detail")
Object detail(@RequestParam("id") Integer id);
}
3.配置消费端application.yml
server: port: 9001 eureka: client: service-url: defaultZone: http://localhost:7001/service-eureka/eureka register-with-eureka: false
4.消费端添加映射模块依赖
<dependency> <groupId>com.vincent</groupId> <artifactId>service-api</artifactId> <version>1.0-SNAPSHOT</version> </dependency>
5.客户端注入需要使用的服务接口映射
package com.vincent.controller;
import com.vincent.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class UserController {
@Autowired
private IUserService userService;
@GetMapping("/detail")
public Object detail(Integer id){
return this.userService.detail(id);
}
}
5.编写消费端启动类
package com.vincent;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.feign.EnableFeignClients;
@SpringBootApplication
@EnableFeignClients({"com.vincent.service"})
@EnableEurekaClient
public class ConsumerApp {
public static void main(String[] args) {
SpringApplication.run(ConsumerApp.class,args);
}
}
@EnableFeignClients 定义Feign接口映射扫描包，IOC容器会自动创建接口实现类
6.访问 http://localhost:9001/detail?id=1
三.总结
Feign接口映射服务端Restful接口会自动依赖Ribbon组件，实现客户端负载均衡。使用接口调用消费端远程接口就像调用本地方法一样。
