使用IntelliJ IDEA在Spring Cloud的Feign项目中使用Hystrix熔断器

Eureka注册中心：《使用IntelliJ IDEA创建Spring Cloud服务注册中心》

服务提供者创建：《使用IntelliJ IDEA创建Spring Cloud的Eureka Client》

Ribbon实现负载均衡：《使用IntelliJ IDEA创建Ribbon项目实现负载均衡》

集成Feign的项目：《使用IntelliJ IDEA创建集成Feign的项目简化服务调用的网络连接》

Ribbon项目中使用Hystrix熔断器：《使用IntelliJ IDEA在Spring Cloud的Ribbon项目中使用Hystrix熔断器》

创建Feign项目

File---new---module---Spring Assistant

点击next

点击next

点击Finish

AcyxfeigntwoApplication.java

package com.acyx.feign;

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

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class AcyxfeigntwoApplication {

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

}

HomeFeignService.java

package com.acyx.feign.service;

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

@FeignClient(value = "acyx-stock")
public interface HomeFeignService {

    @RequestMapping(value = "/home")
    String homeFeign(@RequestParam(value = "name") String name);
}

HomeFeignController.java

package com.acyx.feign.controller;

import com.acyx.feign.service.HomeFeignService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HomeFeignController {

    @Autowired
    private HomeFeignService homeFeignService;

    @RequestMapping("/homeFeign")
    public String homeFeign(String name){

        return homeFeignService.homeFeign(name);
    }
}

application.yml

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 8101
spring:
  application:
    name: acyx-feign

配置项目

在acyxfeigntwo中的application.yml，添加配置，开启hystrix熔断器。修改后，如下：

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/
server:
  port: 8101
spring:
  application:
    name: acyx-feign
feign:
  hystrix:
    enabled: true

pom.xml中添加如下内容：

            org.springframework.cloud
            spring-cloud-openfeign-core
        
		
			org.springframework.cloud
			spring-cloud-starter-openfeign
		

HomeFeignServiceHystric.java

package com.acyx.feign.service.impl;

import com.acyx.feign.service.HomeFeignService;
import org.springframework.stereotype.Component;

@Component
public class HomeFeignServiceHystric implements HomeFeignService {

    @Override
    public String homeFeign(String name) {
        return "sorry, ACYX-STOCK is not normal! Hystrix fallbackMethod execute";
    }
}

HomeFeignService.java中给@FeignClient添加fallback，修改后如下：

package com.acyx.feign.service;

import com.acyx.feign.service.impl.HomeFeignServiceHystric;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value = "acyx-stock",fallback = HomeFeignServiceHystric.class)
public interface HomeFeignService {

    @RequestMapping(value = "/home")
    String homeFeign(@RequestParam(value = "name") String name);
}

依次启动Eureka注册中心、acyxstock、acyxstocktwo、acyxfeigntwo，然后在浏览器中访问：http://127.0.0.1:8761

在启动acyxfeigntwo时控制台报错，如下图：

在pom.xml中添加如下依赖：

			org.springframework.cloud
			spring-cloud-starter-feign
		

点击如下箭头指示的图标，reimport依赖的jar包，出现如下图椭圆标注的unknown

在控制台显示如下内容

Could not find artifact org.springframework.cloud:spring-cloud-starter-feign:pom:unknown in nexus-aliyun (http://maven.aliyun.com/nexus/content/groups/public)

为什么上述提示信息中包含nexus-aliyun呢？因为在本地安装的maven的settings.xml配置文件中mirror配置的是nexus-aliyun。如需配置，可以参考文章《maven中settings.xml配置使用阿里云Maven仓库》

 

出现unknown可尝试添加version信息，查看配置的maven仓库http://maven.aliyun.com/nexus/content/groups/public中的spring-cloud-starter-feign的信息。

在pom.xml中添加如下依赖：

			org.springframework.cloud
			spring-cloud-starter-feign
			2.0.0.M2
		

点击maven中reimport按钮

此时，再次尝试启动acyxfeigntwo，启动成功。

依次启动Eureka注册中心、acyxstock、acyxstocktwo、acyxfeigntwo，然后在浏览器中访问：http://127.0.0.1:8761

测试效果

在浏览器中输入http://127.0.0.1:8101/homeFeign?name=abc

刷新

再次刷新

此时，关闭服务acyxstock、acyxstocktwo

在浏览器中输入http://127.0.0.1:8101/homeFeign?name=abc

Feign在简化网络连接的同时，还使用了Ribbon负载均衡的功能。

参考文档：https://cloud.spring.io/spring-cloud-static/spring-cloud-netflix/2.2.2.RELEASE/reference/html/#how-to-include-hystrix