spring cloud 2.x版本 Feign服务发现教程(内含集成Hystrix熔断机制)

  • 2019 年 11 月 5 日
  • 笔记

前言

本文采用Spring cloud本文为2.1.8RELEASE，version=Greenwich.SR3

本文基于前两篇文章eureka-server和eureka-client的实现。
参考

创建Feign工程

1.1 创建sping boot工程：eureka-feign

1.2 添加pom.xml相关依赖

<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>

1.3 application添加配置信息

spring:    application:      name: eureka-feign    server:    port: 8601    eureka:    instance:      hostname: localhost      lease-renewal-interval-in-seconds: 5      lease-expiration-duration-in-seconds: 10    client:      service-url:        defaultZone: http://eureka1.server.com:8701/eureka/,http://eureka2.server.com:8702/eureka/,http://eureka3.server.com:8703/eureka/

1.4 启动类EurekaFeignApplication增加注解

package spring.cloud.demo.eurekafeign;    import org.springframework.boot.SpringApplication;  import org.springframework.boot.autoconfigure.SpringBootApplication;  import org.springframework.cloud.client.discovery.EnableDiscoveryClient;  import org.springframework.cloud.netflix.hystrix.EnableHystrix;  import org.springframework.cloud.openfeign.EnableFeignClients;    @EnableDiscoveryClient  @EnableFeignClients  @SpringBootApplication  public class EurekaFeignApplication {        public static void main(String[] args) {          SpringApplication.run(EurekaFeignApplication.class, args);      }    }

@EnableDiscoveryClient:这里使用EnableDiscoveryClient注解，在eureka-client已说明，这边就不在阐述

@EnableFeignClients:启用Feign客户端

1.5 创建服务接口EurekaFeignService

package spring.cloud.demo.eurekafeign.service;    import org.springframework.cloud.openfeign.FeignClient;  import org.springframework.web.bind.annotation.RequestMapping;    /**   * @auther: maomao   * @DateT: 2019-09-17   */  @FeignClient(value = "eureka-client")  public interface EurekaFeignService {        @RequestMapping(value = "/info")      String syaHello();  }

@FeignClient:定义Feign客户端，调用远程client。eureka-client代表client的spring.application.name,调用远程地址示例：http://eureka-client/info

1.6 创建EurekaFeignController控制类

package spring.cloud.demo.eurekafeign.controller;    import org.springframework.web.bind.annotation.RequestMapping;  import org.springframework.web.bind.annotation.RestController;  import spring.cloud.demo.eurekafeign.service.EurekaFeignService;    import javax.annotation.Resource;    /**   * @auther: maomao   * @DateT: 2019-09-17   */  @RestController  @RequestMapping("/feign")  public class EurekaFeignController {        @Resource      private EurekaFeignService eurekaFeignService;        @RequestMapping("/sayHello")      public String sayHello() {          return "feign result: " + eurekaFeignService.syaHello();      }    }

1.7 启动eureka-feign服务

可以在eureka-server服务注册中心看到eureka-feign是否注册成功。

红框中内容代表eureka-feign已经正常启动并成功注册到eureka-server服务注册中心。

访问http://localhost:8601/feign/sayHello，显示如下：


多刷新几次可以在浏览器中看到不通的结果，端口是变化的。

Feign默认的负载均衡策略是轮询方式。如果想修改Feign的负载均衡策略请参考eureka-ribbon中的配置

至此，一个简单的单机Feign服务消费者工程就搭建完成了。

彩蛋

Feign集成Hystrix熔断机制

pom.xml增加依赖

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

增加application.yml配置

feign:    hystrix:      enabled: true

修改EurekaFeignService

在@FeignClient注解中增加fallback

package spring.cloud.demo.eurekafeign.service;    import org.springframework.cloud.openfeign.FeignClient;  import org.springframework.web.bind.annotation.RequestMapping;    /**   * @auther: maomao   * @DateT: 2019-09-17   */  @FeignClient(value = "eureka-client", fallback = EurekaFeignServiceFailure.class)  public interface EurekaFeignService {        @RequestMapping(value = "/info")      String syaHello();  }

增加EurekaFeignServiceFailure类：

package spring.cloud.demo.eurekafeign.service;    import org.springframework.stereotype.Service;    /**   * @auther: maomao   * @DateT: 2019-09-17   */  @Service  public class EurekaFeignServiceFailure implements EurekaFeignService {      @Override      public String syaHello() {          return "网络繁忙，请稍后在试";      }  }

启动eureka-feign服务

首先在eureka-client全不启动的情况，访问http://localhost:8601/feign/sayHello看是否全不正常，然后停掉其中一个eureka-client，在多次刷新http://localhost:8601/feign/sayHello,显示如下：


说明增加的Hystrix已经生效。

至此，Feign集成Hystrix熔断机制全部完成。

总结

本文主要简单实现了feign作为服务消费的简单应用和Hystrix的集成。

代码地址

gitHub地址

《Srping Cloud 2.X小白教程》目录

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