spring cloud hystrix

简介

hystrix通过服务隔离、熔断(也可以称为断路)、降级等手段控制依赖服务的延迟与失败。

netflix hystrix

本篇中主要讲解对​​spring​​ cloud 对hystrix的集成，至于如何单独使用hystrix可以参考我分享的​​pdf​​.

spring cloud hystrix

引入依赖

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

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

​​spring-cloud-starter-hystrix​​​​spring-cloud-starter-hystrix-dashboard​​

EnableCircuitBreaker

​​EnableCircuitBreaker​​或者 ​​EnableHystrix​​ 表明​​Spring boot​​工程启用hystrix,两个注解是等价的.​​Application.Java​​

package com.lkl.springcloud.hystrix;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;

/**
 * Created by liaokailin on 16/5/1.
 */
@SpringBootApplication
@EnableCircuitBreaker
@EnableHystrixDashboard
public class Application {

    public static void main(String[] args) {
        new SpringApplicationBuilder(Application.class).web(true).run(args);
    }
}

​​EnableHystrixDashboard​​注解表示启动对hystrix的监控，后面会用到

随后模拟一个调用三方依赖服务

​​controller​​-> ​​service​​ -> ​​dependency service​​

​​controller​​

package com.lkl.springcloud.hystrix.controller;

import com.lkl.springcloud.hystrix.service.HystrixService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * 模拟一个对外的接口
 * Created by liaokailin on 16/5/1.
 */
@RestController
public class HystrixController {

    @Autowired
    private HystrixService service;
    /**
     * 调用依赖的服务
     */
    @RequestMapping("/call")
    public String callDependencyService(){
        return service.callDependencyService();
    }
}

​​service​​

package com.lkl.springcloud.hystrix.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * 依赖服务
 * Created by liaokailin on 16/5/1.
 */
@Service
public class HystrixService {

    @Autowired
    private CallDependencyService dependencyService;
    public String callDependencyService() {
        return dependencyService.mockGetUserInfo();
    }
}

​​dependency service​​

package com.lkl.springcloud.hystrix.service;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.stereotype.Component;

import java.util.Random;

/**
 * 调用依赖服务，通过hystrix包装调用服务
 * Created by liaokailin on 16/5/1.
 */
@Component
public class CallDependencyService {

    private Random random = new Random();
    /**
     * 模拟获取用户信息(通过网络调用)
     * @return
     */
    @HystrixCommand(fallbackMethod = "fallback")
    public String mockGetUserInfo(){
        int randomInt= random.nextInt(10) ;
        if(randomInt<8){  //模拟调用失败情况
            throw new RuntimeException("call dependency service fail.");
        }else{
            return "UserName:liaokailin;number:"+randomInt;
        }
    }

    public String fallback(){
        return "some exception occur call fallback method.";
    }
}

​​HystrixCommand​​ 表明该方法为hystrix包裹，可以对依赖服务进行隔离、降级、快速失败、快速重试等等hystrix相关功能 

该注解属性较多，下面讲解其中几个

  • fallbackMethod 降级方法
  • commandProperties 普通配置属性，可以配置HystrixCommand对应属性，例如采用线程池还是信号量隔离、熔断器熔断规则等等
  • ignoreExceptions 忽略的异常，默认

​​HystrixBadRequestException​​

  • 不计入失败
  • groupKey() 组名称，默认使用类名称
  • commandKey 命令名称，默认使用方法名

Dashboard

运行工程，可以访问 ​​http://localhost:9090/hystrix.stream​​​ 获取dashboard信息，默认最大打开​​5​​个终端获取监控信息，可以增加​​delay​​参数指定获取监控数据间隔时间hystrix.stream肯定是不明智的，官方提供监控​​hystrix-dashboard-#.#.#.war​​​包,下载后放入tomcat中，得到如下界面 

输入​​http://localhost:9090/hystrix.stream​​​ 点击 ​​Monitor stream​​ 访问 ​​http://localhost:/9090/call​​​ 观察进入Dashboard变化 

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