首页 > > 程序设计 > Java技术 >

Spring Cloud（5）：Hystrix的使用

2019-05-18 07:08:17来源：博客园阅读 ()

熔断：类似生活中的保险丝，电流过大就会熔断

降级：类似生活中的旅行，行李箱只有那么大，所以要抛弃一些非必需的物品

熔断降级应用：

某宝双十一商品下单，用户量巨大，于是考虑抛弃相关商品推荐等模块，确保该商品信息和下单功能通畅

熔断和降级的区别以及联系：

1.两者都是为了防止系统崩溃，提高可用性

2.最终给用户的体验是某些功能暂时不可用

3.服务熔断一般是由下游服务故障导致的，服务降级一般是从系统整体负荷考虑，由调用方控制

Hystrix的使用：

基于上一篇Feign的使用：https://www.cnblogs.com/xuyiqing/p/10869026.html

订单服务Order-Service中加入依赖

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

在启动类中加入注解

package org.dreamtech.orderservice;


import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;

import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableFeignClients
@EnableCircuitBreaker
public class OrderServiceApplication {

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

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

Controller层进行修改

package org.dreamtech.orderservice.controller;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.dreamtech.orderservice.service.ProductOrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.Map;

@RestController
@RequestMapping("/api/order")
public class OrderController {
    private final ProductOrderService productOrderService;

    @Autowired
    public OrderController(ProductOrderService productOrderService) {
        this.productOrderService = productOrderService;
    }

    @RequestMapping("/save")
    @HystrixCommand(fallbackMethod = "saveOrderFail")
    public Object save(@RequestParam("user_id") int userId, @RequestParam("product_id") int productId) {
        Map<String, Object> data = new HashMap<>();
        data.put("code", 0);
        data.put("data", productOrderService.save(userId, productId));
        return data;
    }

    private Object saveOrderFail(int userId, int productId) {
        Map<String, Object> msg = new HashMap<>();
        msg.put("code", -1);
        msg.put("msg", "请稍后重试");
        return msg;
    }
}

注意：saveOrderFail方法的参数必须和save的参数一致

依次启动Eureka-Server->Product-Service->Order-Service

访问：http://localhost:8781/api/order/save?user_id=1&product_id=4

正常显示：

{"code":0,"data":{"id":0,"productName":"\"iPhone4 data from port=8771\"","tradeNo":"13933d59-34fd-473a-8dbe-f114bc9fd2b9","price":4444,"createTime":"2019-05-17T03:54:12.682+0000","userId":1,"userName":null}}

这时候我关闭Product-Service，模拟熔断

再次访问：http://localhost:8781/api/order/save?user_id=1&product_id=4

显示：

{"msg":"请稍后重试","code":-1}

说明Hystrix配置和使用成功！

Feign结合Hystrix的使用：

配置Feign允许Hystrix

feign:
  hystrix:
    enabled: true

FeignClient加入fallback处理

package org.dreamtech.orderservice.service;

import org.dreamtech.orderservice.fallback.ProductClientFallback;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(name = "product-service",fallback = ProductClientFallback.class)
public interface ProductClient {
    @RequestMapping("/api/product/find")
    String findById(@RequestParam(value = "id")int id);
}

ProductClientFallback

package org.dreamtech.orderservice.fallback;

import org.dreamtech.orderservice.service.ProductClient;
import org.springframework.stereotype.Component;

@Component
public class ProductClientFallback implements ProductClient {
    @Override
    public String findById(int id) {
        System.out.println("Feign调用Product-Service异常");
        return null;
    }
}

启动项目，访问：http://localhost:8781/api/order/save?user_id=1&product_id=3成功

关闭Product-Service，访问http://localhost:8781/api/order/save?user_id=1&product_id=3

显示

{"msg":"请稍后重试","code":-1}

并且在控制台打印

Feign调用Product-Service异常

服务异常报警通知：

只是熔断和降级是不够了，还需要报警机制

由于访问量较大，要做到只报警一次，那么需要进行标识

通常实现原理基于缓存，比如Redis

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

配置

spring:
  application:
    name: order-service
  redis:
    host: 127.0.0.1
    database: 0
    port: 6379
    timeout: 2000

代码

package org.dreamtech.orderservice.controller;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.apache.commons.lang.StringUtils;
import org.dreamtech.orderservice.service.ProductOrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

@RestController
@RequestMapping("/api/order")
public class OrderController {
    private final ProductOrderService productOrderService;

    private final StringRedisTemplate redisTemplate;

    @Autowired
    public OrderController(ProductOrderService productOrderService, StringRedisTemplate redisTemplate) {
        this.productOrderService = productOrderService;
        this.redisTemplate = redisTemplate;
    }

    @RequestMapping("/save")
    @HystrixCommand(fallbackMethod = "saveOrderFail")
    public Object save(@RequestParam("user_id") int userId, @RequestParam("product_id") int productId) {
        Map<String, Object> data = new HashMap<>();
        data.put("code", 0);
        data.put("data", productOrderService.save(userId, productId));
        return data;
    }

    private Object saveOrderFail(int userId, int productId) {

        String saveOrderKey = "save-order";
        String sendValue = redisTemplate.opsForValue().get(saveOrderKey);

        new Thread(() -> {
            if (StringUtils.isBlank(sendValue)) {
                // TODO 由于没有短信发送接口，模拟发送短信
                System.out.println("短信发送成功");
                redisTemplate.opsForValue().set(saveOrderKey, "save-order-fail", 20, TimeUnit.SECONDS);
            } else {
                System.out.println("已经发送过短信，20秒内不重复发送");
            }
        }).start();


        Map<String, Object> msg = new HashMap<>();
        msg.put("code", -1);
        msg.put("msg", "请稍后重试");
        return msg;
    }
}

测试

启动项目，访问http://localhost:8781/api/order/save?user_id=1&product_id=3没有问题

关闭Product-Service再访问，控制台打印：

Feign调用Product-Service异常
短信发送成功

再次访问：

Feign调用Product-Service异常
已经发送过短信，20秒内不重复发送

等待20秒访问：

Feign调用Product-Service异常
短信发送成功

成功

或者更进一步，拿到IP，发送短信

package org.dreamtech.orderservice.controller;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.apache.commons.lang.StringUtils;
import org.dreamtech.orderservice.service.ProductOrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletRequest;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

@RestController
@RequestMapping("/api/order")
public class OrderController {
    private final ProductOrderService productOrderService;

    private final StringRedisTemplate redisTemplate;

    @Autowired
    public OrderController(ProductOrderService productOrderService, StringRedisTemplate redisTemplate) {
        this.productOrderService = productOrderService;
        this.redisTemplate = redisTemplate;
    }

    @RequestMapping("/save")
    @HystrixCommand(fallbackMethod = "saveOrderFail")
    public Object save(@RequestParam("user_id") int userId, @RequestParam("product_id") int productId, HttpServletRequest request) {
        Map<String, Object> data = new HashMap<>();
        data.put("code", 0);
        data.put("data", productOrderService.save(userId, productId));
        return data;
    }

    private Object saveOrderFail(int userId, int productId,HttpServletRequest request) {

        String saveOrderKey = "save-order";
        String sendValue = redisTemplate.opsForValue().get(saveOrderKey);
        String ip = request.getRemoteAddr();

        new Thread(() -> {
            if (StringUtils.isBlank(sendValue)) {
                // TODO 由于没有短信发送接口，模拟发送短信
                System.out.println("短信发送成功，紧急情况，用户下单失败！来自于IP："+ip);
                redisTemplate.opsForValue().set(saveOrderKey, "save-order-fail", 20, TimeUnit.SECONDS);
            } else {
                System.out.println("已经发送过短信，20秒内不重复发送");
            }
        }).start();


        Map<String, Object> msg = new HashMap<>();
        msg.put("code", -1);
        msg.put("msg", "请稍后重试");
        return msg;
    }
}

Hystrix自定义配置：

关闭超时时间（实际情况不要用）

hystrix:
  command:
    default:
      execution:
        timeout:
          enabled: false

修改超时时间为4秒：

hystrix:
  command:
    default:
      execution:
        isolation:
          thread:
            timeoutInMilliseconds: 4000

不过Feign默认超时时间少于4秒，所以对Feign也进行修改：

feign:
  hystrix:
    enabled: true
  client:
    config:
      default:
        connectTimeout: 4000
        readTimeout: 4000

感觉YML的配置真的不舒服，不如继续用PROPERTIES

Hystrix-Dashboard：对Hystrix过程和结果的可视化界面

Hystrix-Dashboard的使用：

加入依赖：不只是Dashboard，还依赖于SpringBoot的监控Actuator

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

在启动类中加入注解：@EnableHystrixDashboard

package org.dreamtech.orderservice;


import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableFeignClients
@EnableCircuitBreaker
@EnableHystrixDashboard
public class OrderServiceApplication {

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

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

启动后访问：http://localhost:8781/hystrix

根据提示输入http://localhost:8781/actuator/hystrix.stream，发现报错：

Unable to connect to Command Metric Stream.

而且我如我直接访问http://localhost:8781/actuator/hystrix.stream也会显示404

解决：配置文件

management:
  endpoints:
    web:
      exposure:
        include: "*"

原因：配置Actuator开启全部端点

启动后访问：http://localhost:8781/hystrix

根据提示输入http://localhost:8781/actuator/hystrix.stream

或者直接访问：http://localhost:8781/actuator/hystrix.stream不会报错

原文链接:https://www.cnblogs.com/xuyiqing/p/10874654.html
如有疑问请与原作者联系

标签：

版权申明：本站文章部分自网络，如有侵权，请联系：west999com@outlook.com
特别注意：本站所有转载文章言论不代表本站观点，本站所提供的摄影照片，插画，设计作品，如需使用，请与原作者联系，版权归原作者所有

上一篇：Elasticsearch自定义客户端（TransportClient）资源池

下一篇：调整JVM内存大小

Spring系列.ApplicationContext接口 2020-06-11
springboot2配置JavaMelody与springMVC配置JavaMelody 2020-06-11
给你一份超详细 Spring Boot 知识清单 2020-06-11
SpringBoot 2.3 整合最新版 ShardingJdbc + Druid + MyBatis 2020-06-11
掌握SpringBoot-2.3的容器探针：实战篇 2020-06-11

IDC资讯：主机资讯注册资讯托管资讯 vps资讯网站建设

网站运营：建站经验策划盈利搜索优化网站推广免费资源

网站联盟：联盟新闻联盟介绍联盟点评网赚技巧

行业资讯：搜索引擎网络游戏电子商务广告传媒

网络编程： Asp.Net编程 Asp编程 Php编程 Xml编程 Access Mssql Mysql 其它

服务器技术： Web服务器 Ftp服务器 Mail服务器 Dns服务器安全防护

软件技巧：其它软件 Word Excel Powerpoint Ghost Vista QQ空间 QQ FlashGet 迅雷

网页制作： FrontPages Dreamweaver Javascript css photoshop fireworks Flash

程序设计： Java技术 C/C++ VB delphi

网络知识：网络协议网络安全网络管理组网方案 Cisco技术

操作系统： Win2000 WinXP Win2003 Mac OS Linux FreeBSD

热门词条

最新资讯

热门关注

热门标签