服务消费端开启hystrix熔断机制（基于Feign）

阳光穿透心脏的1/2处 2022-05-16 00:08 164阅读 0赞

# 服务消费端开启hystrix熔断机制（基于Feign） #

## 博文概述 ##

本篇博文通过feign实现服务消费者，并开启了hystrix熔断机制确保服务提供者在服务异常的情况下，可以将服务请求转发至相应的服务异常处理方法中，以确保整个服务过程不会被阻塞。

## 实现步骤分析 ##

### 引入相关依赖依赖 ###

<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>

### 创建application.yml文件 ###

server:
      port: 9000 # 指定工程端口号
    
    feign: 
      hystrix: 
        enabled: true # 启动hystrix熔断机制
    eureka: 
      client:
        register-with-eureka: false
        service-url: 
          # eureka Server端地址
          defaultZone: http://peer1:8761/eureka/,http://peer2:8762/eureka/

### 创建springcloud-service-consumer-feign-hystrix启动类 ###

import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.netflix.feign.EnableFeignClients;
    
    @SpringBootApplication
    @EnableFeignClients // 启动Feign
    public class Application { 
        public static void main(String[] args) throws Exception {
            SpringApplication.run(Application.class, args);
        }
    
    }

### 服务消费示例代码 ###

#### 消费端Controller代码 ####

import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import cn.tyrone.springcloud.service.consumer.feign.hystrix.service.ServiceProviderConsumerFeignService;
    
    /** * 服务消费端 * 这是服务消费端暴露给客户端请求的地址 * @author shanglishuai * */
    @RestController // @RestController <==> @Controller + @ResponseBody
    public class ServiceProviderConsumerController { 
    
        // 注入Feign接口
        @Autowired
        private ServiceProviderConsumerFeignService feignService;
    
        /** * 服务消费端方法 * 该方法通过与@FeignClient("MICROSERVICE-SERVICE-PROVIDER")标记的接口实现与服务提供者的交互 * @return */
        @RequestMapping("/consumer/request/info")
        public String requestInfo(boolean flag) {
            return feignService.requestInfo();
        }
    
    }

#### FeignClient接口代码 ####

import org.springframework.cloud.netflix.feign.FeignClient;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    /** * @FeignClient("MICROSERVICE-SERVICE-PROVIDER") * MICROSERVICE-SERVICE-PROVIDER:是一个服务提供者的实例名称 * 用于标记一个可用的服务的名称，同时创建一个Ribbon负载均衡器 * fallbackFactory指定用于处理服务提供者服务异常过程的类 * 该接口用于实现与服务提供者进行交互，接口中的方法与服务提供者需要暴露的方法一一对应 */
    @FeignClient(value = "MICROSERVICE-SERVICE-PROVIDER", fallbackFactory = ServiceProviderConsumerFeignServiceFallbackFactory.class)
    public interface ServiceProviderConsumerFeignService { 
    
        /** * 获取请求URL，对应着服务提供者中的方法 * @return */
        @RequestMapping("/provider/request/info")
        public String requestInfo() ;
    }

#### fallbackFactory代码 ####

import org.springframework.stereotype.Component;
    
    import feign.hystrix.FallbackFactory;
    
    /** * 该类实现FallbackFactory这个接口，并注入需要被hystrix监控的接口ServiceProviderConsumerFeignService， * 用来处理被hystrix监控的服务发生异常后的处理过程 * @author shanglishuai * */
    @Component
    public class ServiceProviderConsumerFeignServiceFallbackFactory implements FallbackFactory<ServiceProviderConsumerFeignService> { 
    
        @Override
        public ServiceProviderConsumerFeignService create(Throwable cause) {
            return new ServiceProviderConsumerFeignService() {
    
                @Override
                public String requestInfo() {
                    try {
                        /* * 休眠2s，模拟被hystrix监控的服务发生异常后的处理过程 */
                        Thread.sleep(2000L);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
    
                    return "【/provider/request/info】服务异常。。。。。";
                }
    
            };
        }
    
    }

### 测试 ###

启动本项目后，通过浏览器内访问`http://localhost:9000/consumer/request/info`，在服务正常的情况下会返回请求的URL, 在服务不正常的情况将会返回`【/provider/request/info】服务异常。。。。。`这样的消息。为了测试是否达到了熔断机制，直接启动本项目即可，不需要启动`Eureka Server`注册中心和服务提供者工程。

熔断机制成功的话，会出现如下图结果：  
![这里写图片描述][70]

源代码链接：  
[https://github.com/myNameIssls/springcloud-study/tree/master/springcloud-service-consumer-feign-hystrix][https_github.com_myNameIssls_springcloud-study_tree_master_springcloud-service-consumer-feign-hystrix]

参考链接：  
[http://cloud.spring.io/spring-cloud-static/Finchley.SR1/multi/multi\_\_circuit\_breaker\_hystrix\_clients.html][http_cloud.spring.io_spring-cloud-static_Finchley.SR1_multi_multi_circuit_breaker_hystrix_clients.html]  
[http://cloud.spring.io/spring-cloud-static/Finchley.SR1/multi/multi\_spring-cloud-feign.html\#spring-cloud-feign-hystrix][http_cloud.spring.io_spring-cloud-static_Finchley.SR1_multi_multi_spring-cloud-feign.html_spring-cloud-feign-hystrix]

[70]: /images/20220516/02e6c42dcdd54dd4a34f5f630eb78d04.png
[https_github.com_myNameIssls_springcloud-study_tree_master_springcloud-service-consumer-feign-hystrix]: https://github.com/myNameIssls/springcloud-study/tree/master/springcloud-service-consumer-feign-hystrix
[http_cloud.spring.io_spring-cloud-static_Finchley.SR1_multi_multi_circuit_breaker_hystrix_clients.html]: http://cloud.spring.io/spring-cloud-static/Finchley.SR1/multi/multi__circuit_breaker_hystrix_clients.html
[http_cloud.spring.io_spring-cloud-static_Finchley.SR1_multi_multi_spring-cloud-feign.html_spring-cloud-feign-hystrix]: http://cloud.spring.io/spring-cloud-static/Finchley.SR1/multi/multi_spring-cloud-feign.html#spring-cloud-feign-hystrix