三、Feign

一、Feign简介

Feign 是Netflix声明式，模板化的HTTP客户端。

Spring Cloud Feign是基于Netflix feign实现，整合了Spring Cloud Ribbon和Spring Cloud Hystrix，除了提供这两者的强大功能外，还提供了一种声明式的Web服务客户端定义的方式。

Feign默认集成了Ribbon,实现负载均衡。

 

二、搭建服务消费者feign

<?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>mo-cloud</artifactId>
        <groupId>com.mo</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>feign</artifactId>
    <description>服务消费feign</description>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

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

        <!-- feign依赖 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
    </dependencies>

</project>

server:
  port: 0
spring:
  application:
    name: feign
eureka:
  client:
    service-url:
      default-zone: http://127.0.0.1:8761/eureka/
  instance:
    prefer-ip-address: true
    instance-id: ${spring.application.name}:${random.int}

package com.mo.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * feign接口
 * FeignClient 表示这个接口调用哪个服务
 *
 * @author x.pan
 * @email px5215201314@163.com
 * @date 2020/4/6 21:28
 */
@FeignClient("service-hello")
public interface HelloService {

    /**
     * 通过feign调用指定服务
     *
     * @return
     */
    @GetMapping("/hello")
    String hello();
}

package com.mo;

import com.mo.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * EnableFeignClients 开启feign的功能
 *
 * @author x.pan
 * @email px5215201314@163.com
 * @date 2020/4/6 21:26
 */
@RestController
@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class FeignApplication {

    @Autowired
    private HelloService helloService;

    public static void main(String[] args) {
        SpringApplication.run(FeignApplication.class, args);
    }

    /**
     * 通过feign消费service-hello提供的服务
     *
     * @return
     */
    @GetMapping("/hello")
    public String hello() {
        return helloService.hello();
    }
}

 效果：请求feign服务的hello接口，会交替显示service-hello两个服务执行结果