Java后端爱上SpringCloud 第三节:熔断器 Hystrix

• 一些链接
• 为什么要用熔断器？
• Ribbon结合Hystrix
• Feign结合Hystrix

一些链接

• Eureka+Zuul+Ribbon+Feign+Hystrix构建微服务架构
• 一系列很详细的Hystrix
• SpringCloud之Feign与Hystrix的整合
• 网上介绍熔断器 Hystrix的还很多的

为什么要用熔断器？

Ribbon结合Hystrix

继续My-Spring-Ribbon工程。引入依赖：

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

我们再改造一下RibbonControler类。

package com.hyn.cloud.ribbon.controler;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.hyn.cloud.ribbon.service.RibbonService;

@RestController
@RequestMapping("/ribbon")
public class RibbonControler {

@Autowired
RibbonService iRibbonService;

@RequestMapping(value = "/name",method=RequestMethod.GET)
@ResponseBody
public String ribbon(@RequestParam String name){
return iRibbonService.sendFeignServer(name);
}

@RequestMapping(value = "/name2",method=RequestMethod.GET)
@ResponseBody
public String ribbon2(@RequestParam String name){
String respResult="I am ribbon,My name2 is "+name;
return respResult;
}
}

再来改造一下：

package com.hyn.cloud.ribbon.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;

@Service
public class RibbonService {

/**
* 注入RestTemplate
*/
@Autowired
RestTemplate restTemplate;

@HystrixCommand(fallbackMethod = "errorSendFeignServer",
commandProperties = {
////指定多久超时，单位毫秒。超时进fallback
@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "4000"),
//判断熔断的最少请求数，默认是10；只有在一个统计窗口内处理的请求数量达到这个阈值，才会进行熔断与否的判断
@HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "10"),
//判断熔断的阈值，默认值50，表示在一个统计窗口内有50%的请求处理失败，会触发熔断
@HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "10"),
}
)
public String sendFeignServer(String name)
{
String respResult="I am ribbon,My name is "+name;
String url="http://SPRING-BOOT-FEIGN/feign/name?name=";
return restTemplate.getForObject(url+respResult, String.class);
}

public String errorSendFeignServer(String name)
{
return "feign server is die!";
}
}

依次启动一下：My-Spring-Eureka，My-Spring-Admin，My-Spring-Feign，My-Spring-Ribbon
正常现在请求：
http://127.0.0.1:8765/ribbon/name?name=hyn

关闭My-Spring-Feign工程：

Feign结合Hystrix

feign不用引入Hystrix依赖，因为本身就集成这。但是feign默认是不开启熔断功能的要在application.yml添加以下配置：

feign:
hystrix:
enabled: true

改造FeignControler

package com.hyn.cloud.feign.controler;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.hyn.cloud.feign.service.FeignService;

@RestController
@RequestMapping("/feign")
public class FeignControler {

@Autowired
FeignService feignService;

@RequestMapping(value = "/name",method=RequestMethod.GET)
public String feign(@RequestParam String name){
return feignService.getName(name);
}
}

改造FeignService

package com.hyn.cloud.feign.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value = "SPRING-BOOT-RIBBO",fallback=FeignServiceHystric.class,configuration=FeignDisableHystrixConfiguration.class )
public interface FeignService {

@RequestMapping(value = "/ribbon/name2",method = RequestMethod.GET)
String getName(@RequestParam("name")String name);

}

新增HystrixFeignConfiguration

package com.hyn.cloud.feign.service;

import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Scope;

import com.netflix.hystrix.HystrixCommand;

import feign.Feign;
import feign.hystrix.HystrixFeign;

@Configuration
public class FeignDisableHystrixConfiguration {

@Configuration
@ConditionalOnClass({ HystrixCommand.class, HystrixFeign.class })
protected static class HystrixFeignConfiguration {
@Bean
@Scope("prototype")
public Feign.Builder feignHystrixBuilder() {
return HystrixFeign.builder();
}
}

}

新增FeignServiceHystric

package com.hyn.cloud.feign.service;

import org.springframework.stereotype.Component;

@Component
public class FeignServiceHystric implements FeignService{
@Override
public String getName(String name) {
return "ribbon server is die!";
}
}

测试一下：
依次启动一下：My-Spring-Eureka，My-Spring-Admin，My-Spring-Feign，My-Spring-Ribbon
正常请求：

关闭My-Spring-Ribbon：

有兴趣的同学，可以自行测一下超时的请求。异常的请求。