SpringCloud(Finchley版)3 - Feign

一, 简介

    Feign默认集成了Ribbon, 并和Eureka结合, 默认实现了负载均衡的效果. 接口注解调用. 方便开发;

二, 具体实现

    1, 建立服务 cloud-d SERVCIE-D, pom.xml 

<?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">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.gy.cloud</groupId>
        <artifactId>cloud</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <artifactId>cloud-d</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

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

</project>

    2, cloud-d  application.yml

server:
  port: 8764

spring:
  application:
    name: service-d

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

# Feign 断路由配置
feign:
  hystrix:
    enabled: true

    3, cloud-d  CloudDApplication

package com.gy.cloud.cloudd;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class CloudDApplication {

    public static void main(String[] args) {
        SpringApplication.run(CloudDApplication.class, args);
        System.out.println("=== 消费服务D启动成功 ===");
    }
}

    4, HiController

package com.gy.cloud.cloudd;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HiController {

    @Autowired
    private SchedulingService schedulingService;

    @GetMapping("hi")
    public Object hi(){
        return schedulingService.sayHiFromClientOne("SERVICE-D");
    }

}

    5, SchedulingService

package com.gy.cloud.cloudd;

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

@FeignClient(value = "service-b", fallback = SchedulingServiceImpl.class)
public interface SchedulingService {

    @GetMapping("hi")
    String sayHiFromClientOne(@RequestParam(value = "name") String name);

}

    6, SchedulingServiceImpl

package com.gy.cloud.cloudd;

import org.springframework.stereotype.Component;

@Component
public class SchedulingServiceImpl implements SchedulingService {
    @Override
    public String sayHiFromClientOne(String name) {
        return "Sorry " + name;
    }
}

    7, 启动服务 SERVICE-D 访问  http://localhost:8764/hi

    8, 断开服务 SERVICE-B 访问 : http://localhost:8764/hi

 三, 总结

    Feign 中 使用 断路器

# Feign 断路由配置
feign:
  hystrix:
    enabled: true

学习文档

方志朋的博客 :  https://www.fangzhipeng.com/springcloud/2018/08/30/sc-f3-feign/

项目源码:  https://gitee.com/ge.yang/spring-demo/tree/master/cloud