摘要：公眾號(hào)樂(lè)園上編說(shuō)了整合斷路器，這篇來(lái)看看如何整合斷路器，整合斷路器也是相對(duì)比較簡(jiǎn)單的。默認(rèn)已經(jīng)自帶斷路器，所以不需要像整合斷路器那樣需要在的啟動(dòng)類添加注解。但是自帶斷路器并沒有打開，需要做些額外的配置。

公眾號(hào)： java樂(lè)園

上編說(shuō)了《RestTemplate+Ribbon整合斷路器Hystrix》，這篇來(lái)看看如何Feign整合斷路器Hystrix，F(xiàn)eign整合斷路器Hystrix也是相對(duì)比較簡(jiǎn)單的。Feign默認(rèn)已經(jīng)自帶斷路器Hystrix，所以不需要像RestTemplate+Ribbon整合斷路器Hystrix那樣需要在SpringBoot的啟動(dòng)類添加注解。但是Feign自帶斷路器并沒有打開，需要做些額外的配置。

feign:
   hystrix:
     enabled: true

1、 新建項(xiàng)目sc-eureka-client-consumer-feign-hystrix，對(duì)應(yīng)的pom.xml文件如下

    4.0.0

    spring-cloud
    sc-eureka-client-consumer-feign
    0.0.1-SNAPSHOT
    jar

    sc-eureka-client-consumer-feign
    http://maven.apache.org

    
        org.springframework.boot
        spring-boot-starter-parent
        2.0.4.RELEASE
    

    
        
            
                org.springframework.cloud
                spring-cloud-dependencies
                Finchley.RELEASE
                pom
                import
            

        
    

    
        UTF-8
        1.8
        1.8
    

    
    
        
        
            org.springframework.cloud
            spring-cloud-starter-netflix-eureka-client
        

        
            org.springframework.boot
            spring-boot-starter-web
        
        
        

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

備注：從繼續(xù)關(guān)系可以看出spring-cloud-starter-openfeign已經(jīng)集成斷路器Hystrix

2、 新建springboot啟動(dòng)類

package sc.consumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
public class ConsumerFeignApplication {
    
    public static void main(String[] args) {
        SpringApplication.run(ConsumerFeignApplication.class, args);
    }

}

3、 新建配置文件bootstrap.yml和application.yml
bootstrap.yml

server:
  port: 5800

application.yml

spring:
  application:
    name: sc-eureka-client-consumer-feign-hystrix

eureka:
  client:
    registerWithEureka: true #是否將自己注冊(cè)到Eureka服務(wù)中，默認(rèn)為true
    fetchRegistry: true #是否從Eureka中獲取注冊(cè)信息，默認(rèn)為true
    serviceUrl:
      defaultZone: http://localhost:5001/eureka/
 
feign:
  hystrix:
enabled: true

說(shuō)明：在application.yml配置文件添加了開啟斷路器Hystrix的配置項(xiàng)

4、 新建服務(wù)消費(fèi)者類UserService.java

package sc.consumer.service;

import java.util.Map;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;

import sc.consumer.model.User;
import sc.consumer.service.hystrix.UserServiceHystrix;

@FeignClient(value="sc-eureka-client-provider", fallback=UserServiceHystrix.class)
public interface UserService {

    @GetMapping("/user/getUser/{id}")
    Map getUser(@PathVariable(value ="id") Long id);

    @RequestMapping("/user/listUser")
    Map listUser();

    @PostMapping("/user/addUser")
    Map addUser(@RequestBody User user);

    @PutMapping("/user/updateUser")
    Map updateUser(@RequestBody User user);

    @DeleteMapping("/user/deleteUser/{id}")
    Map deleteUser(@PathVariable(value ="id") Long id);

}

可以看到在該類的FeignClient注解上添加了一個(gè)屬性fallback

5、 新建斷路器處理類UserServiceHystrix.java

package sc.consumer.service.hystrix;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.springframework.stereotype.Component;

import sc.consumer.model.User;
import sc.consumer.service.UserService;

@Component
public class UserServiceHystrix  implements UserService{

    @Override
    public Map getUser(Long id) {
        Map result = new HashMap();
        result.put("code", "000000");
        result.put("msg", "success");
        User u = new User();
        u.setId(-1L);
        u.setUserName("failBackName");
        result.put("body", u);
        return result;
    }

    @Override
    public Map listUser() {
        Map result = new HashMap();
        result.put("code", "000000");
        result.put("msg", "success");
        List list = new ArrayList();
        User u = new User();
        u.setId(-1L);
        u.setUserName("failBackName");
        list.add(u);
        result.put("body", list);
        return result;
    }

    @Override
    public Map addUser(User user) {
        Map result = new HashMap();
        result.put("code", "000000");
        result.put("msg", "success");
        result.put("body", 0);
        return result;
    }

    @Override
    public Map updateUser(User user) {
        Map result = new HashMap();
        result.put("code", "000000");
        result.put("msg", "success");
        result.put("body", 0);
        return result;
    }

    @Override
    public Map deleteUser(Long id) {
        Map result = new HashMap();
        result.put("code", "000000");
        result.put("msg", "success");
        result.put("body", 0);
        return result;
    }

}

該類實(shí)現(xiàn)了UserService接口，并實(shí)現(xiàn)了該接口的所有方法。

6、 分別啟動(dòng)注冊(cè)中心sc-eureka-server和服務(wù)提供者sc-eureka-client-provider

7、 啟動(dòng)sc-eureka-client-consumer-feign-hystrix，并驗(yàn)證是否啟動(dòng)成功
方式一：查看日志看看對(duì)應(yīng)的端口是啟動(dòng)

方式二：查看注冊(cè)中心是否注冊(cè)成功

8、 使用postman驗(yàn)證斷路器是否啟用
上篇從服務(wù)提供者是否正常啟動(dòng)驗(yàn)證斷路器是否啟動(dòng)，今天看看從數(shù)據(jù)庫(kù)是否啟動(dòng)來(lái)驗(yàn)證斷路器是否啟動(dòng)
（1）MySQL服務(wù)正常啟動(dòng)時(shí)訪問(wèn)：
http://127.0.0.1:5800/feign/user/listUser

（2）MySQL服務(wù)關(guān)閉時(shí)訪問(wèn)
http://127.0.0.1:5800/feign/user/listUser

再看下后臺(tái)日志：

其他接口可以自行按照以上方式進(jìn)行驗(yàn)證，看看斷路器是否啟動(dòng)