022 斷路器Hystrix

時間 2020-02-13

標籤斷路器 hystrix 简体版

原文原文鏈接

1 說明

微服務之間調用這一篇寫了經過ribbon、feign、http方式實現微服務通訊，這一篇斷路器基於上篇git

2 整合Hystrix

pom依賴：spring

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

啓動類添加 @EnableHystrix 註解bash

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@EnableHystrix
public class SalesApplication {
    
    @Bean
    @LoadBalanced
    RestTemplate restTemplate() {
    	return new RestTemplate();
    }

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

}

接口以下，爲了演示不一樣熔斷方式，這裏有兩個 Feign 方式接口app

@RequestMapping("/sales")
public interface SalesRest {
    @RequestMapping(value = "/queryGoodsListByRibbon", method = RequestMethod.GET)
    Object queryGoodsListByRibbon();
    
    @RequestMapping(value = "/queryGoodsListByFeign", method = RequestMethod.GET)
    Object queryGoodsListByFeign();
    
    @RequestMapping(value = "/queryGoodsListByFeign2", method = RequestMethod.GET)
    Object queryGoodsListByFeign2();
    
    @RequestMapping(value = "/queryGoodsListByHttp", method = RequestMethod.GET)
    Object queryGoodsListByHttp();
}

通用方式熔斷：在方法上添加 @HystrixCommand(fallbackMethod = "CommonFallback") ，指定目標方法調取不到後執行 CommonFallback() 熔斷方法ide

@RestController
public class SalesRestImpl implements SalesRest {

    @Autowired
    private SalesService salesService;

    @Override
    @HystrixCommand(fallbackMethod = "CommonFallback")
    public String queryGoodsListByHttp() {
    	return salesService.queryGoodsListByHttp();
    }

    @Override
    @HystrixCommand(fallbackMethod = "CommonFallback")
    public String queryGoodsListByRibbon() {
    	return salesService.queryGoodsListByRibbon();
    }

    @Override
    @HystrixCommand(fallbackMethod = "CommonFallback")
    public String queryGoodsListByFeign() {
    	return salesService.queryGoodsListByFeign();
    }

    @Override
    public String queryGoodsListByFeign2() {
    	return salesService.queryGoodsListByFeign();
    }
    
    public String CommonFallback() {
    	return "CommonFallback";
    }

}

具體方法調用：微服務

@Service
public class SalesService {
	
	@Autowired
	RestTemplate restTemplate;
	
	@Autowired
	UserFeignClient userFeignClient;
	
	private static final String RIBBON_URL = "http://user:8082/user/getUserInfo";
	private static final String HTTP_URL = "http://127.0.0.1:8082/user/getUserInfo";
	private static final String IP = IpUtil.getIp();

	public String queryGoodsListByRibbon() {
		String sales_result = "queryGoodsListByRibbon success : [sales_ip:" + IP + "] ";
		String result = restTemplate.getForObject(RIBBON_URL, String.class);
		return sales_result + result;
	}

	public String queryGoodsListByFeign() {
		String sales_result = "queryGoodsListByFeign success : [sales_ip:" + IP + "] ";
		String result = (String) userFeignClient.getUserInfo();
		return sales_result + result;
	}

	public String queryGoodsListByHttp() {
		String sales_result = "queryGoodsListByHttp success : [sales_ip:" + IP + "] ";
		String result = HttpClientUtil.doGet(HTTP_URL);
		return sales_result + result;
	}
}

Feign 熔斷：給 FeignClient 接口指定一個 fallback 實現類，而後該類實現 FeignClient 的接口，這樣接口調不通時便會調用 fallback 實現類中的相應方法：spa

@FeignClient(name = "USER", fallback = UserFeignClientFallback.class)
public interface UserFeignClient {
	@RequestMapping(value = "/user/getUserInfo", method = RequestMethod.GET)
	String getUserInfo();
}

UserFeignClientFallback.class.net

@Component
public class UserFeignClientFallback implements UserFeignClient {
	@Override
	public String getUserInfo() {
		return "feign client fallback";
	}
}

3 運行結果

啓動 eureka 和 sales，不啓動 user ，觀察接口輸出rest

http://127.0.0.1:8081/sales/queryGoodsListByRibbon 
--> CommonFallback

http://127.0.0.1:8081/sales/queryGoodsListByHttp
--> CommonFallback

http://127.0.0.1:8081/sales/queryGoodsListByFeign
--> CommonFallback

http://127.0.0.1:8081/sales/queryGoodsListByFeign2
--> queryGoodsListByFeign success : [sales_ip:192.168.0.102] feign client fallback