SpringCloud-----服務降級--用戶端熔斷器Hystrix

1、服務降級的本質

服務的本質就是服務暫停。

服務降級是在用戶端實作的，與服務端沒有關系。

2、用戶端添加FallbackFactory實作類，讓Spring容器管理

package com.zemel.service.fallback;

import java.util.List;

import org.springframework.stereotype.Component;

import com.zemel.service.IDeptClientService;
import com.zemel.vo.Dept;

import feign.hystrix.FallbackFactory;

@Component
public class IDeptClientServiceFallbackFactory implements FallbackFactory<IDeptClientService> {

	@Override
	public IDeptClientService create(Throwable arg0) {
		
		return new IDeptClientService() {
			
			@Override
			public List<Dept> list() {
				
				return null;
			}
			
			@Override
			public Dept get(Long id) {
				Dept dept = new Dept();
				dept.setDeptno(888888L);
				dept.setDname("【ERROR】 Feign-Hystrix");
				dept.setLoc("Consumer用戶端提供");
				return dept;
			}
			
			@Override
			public boolean add(Dept dept) {
				// TODO Auto-generated method stub
				return false;
			}
		};
	}

	
}
           

3、服務調用類接入fallbackFactory類

package com.zemel.service;

import java.util.List;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;

import com.zemel.common.FeignClientConfig;
import com.zemel.service.fallback.IDeptClientServiceFallbackFactory;
import com.zemel.vo.Dept;

@FeignClient(value="DEPT-8001", configuration=FeignClientConfig.class,fallbackFactory=IDeptClientServiceFallbackFactory.class)
public interface IDeptClientService {

	@GetMapping(value="/dept/get/{id}")
	public Dept get(@PathVariable("id") Long id);
	
	@GetMapping(value="/dept/list")
	public List<Dept> list();
	
	@PostMapping(value="/dept/add")
	public boolean add(Dept dept);
	
}
           

4、Feign端啟動類修改

/**
 * Hello world!
 *
 */
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients(basePackages={"com.zemel.service"})
@ComponentScan("com.zemel.service,com.zemel.consumer") // 掃描元件配置包路徑
public class FeignApp {
	public static void main(String[] args) {
		SpringApplication.run(FeignApp.class, args);
	}
	
	
}
           

application.yml修改

feign:
  hystrix:
    enabled: true
           

實作的過程可能出現錯誤如下，啟動錯誤