SpringCloud（5）-使用断路器

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我是靠谱客的博主坦率雪糕，最近开发中收集的这篇文章主要介绍SpringCloud（5）-使用断路器，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

由于网络原因或者自身的原因，服务并不能保证100%可用，如果单个服务出现问题，调用这个服务就会出现线程阻塞，此时若有大量的请求涌入，Servlet容器的线程资源会被消耗完毕，导致服务瘫痪。服务与服务之间的依赖性，故障会传播，会对整个微服务系统造成灾难性的严重后果，这就是服务故障的“雪崩”效应。

为了解决这个问题，业界提出了断路器模型

断路器的使用

pom.xml的配置依赖

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

application.properties的配置

server.port=85
spring.application.name=consume
eureka.client.service-url.defaultZone=http://master:81/eureka/
feign.hystrix.enabled=true

启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.cloud.netflix.hystrix.dashboard.EnableHystrixDashboard;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableFeignClients
@EnableDiscoveryClient
@EnableHystrix
@EnableHystrixDashboard
public class EurekaHelloConsumeApplication {

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

Feign请求的接口类

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 = "provider",fallback = FeignServiceImpl.class)
public interface FegionService {

    @RequestMapping(method = RequestMethod.GET)
     String feignHello(@RequestParam(value = "name") String name);
}

在fegin中使用，写一个feginServiceImpl继承接口FegionService

import org.springframework.stereotype.Component;

@Component
public class FeignServiceImpl implements FegionService {
    @Override
    public String feignHello(String name) {
        return "暂时无法访问";
    }
}

在Ribbon中使用断路器

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

@Service
public class ConsumeService {
    @Autowired
    private RestTemplate restTemplate;
    @HystrixCommand(fallbackMethod = "consumeHelloError")
    public String consumeHello(){
        return restTemplate.getForObject("http://provider?name=唐陈",String.class);
    }
    public String consumeHelloError(){
        return "暂时无法访问";
    }
}