SpringCloud学习（五）-- hystrix学习

待我称王封你为后i 2022-12-25 07:57 226阅读 0赞

# 一，引入必要的包 #

<dependency>
                    <groupId>com.netflix.hystrix</groupId>
                    <artifactId>hystrix-javanica</artifactId>
                    <version>${hystrix.version}</version>
                </dependency>

# 二、添加部分配置 #

调用方Application入口，增加@EnableHystrix

@SpringBootApplication
    @EnableDiscoveryClient //开启eureka客户端发现功能
    @EnableHystrix //开始hystrix
    public class ConsumerApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(ConsumerApplication.class,args);
        }
    
        @Bean
        @LoadBalanced//开启Ribbon的负载均衡，调用时，可以通过user-service名字，找到对应的服务。
        public RestTemplate restTemplate(){
            return new RestTemplate();
        }
    }

对应的方法，配置熔断时执行方法

@GetMapping("/{id}")
        @HystrixCommand(defaultFallback = "defalutFallback")
        public String queryById(@PathVariable Long id){
    
            if(id == 1){
                throw new RuntimeException("太忙了");
            }
    
            //String url = "http://localhost:9091/user/1";
    
    //        List<ServiceInstance> userInstances = discoveryClient.getInstances("user-service");
    //
    //        ServiceInstance userInstance = userInstances.get(0);
    //
    //        String url = "http://"+userInstance.getHost()+":"+userInstance.getPort()+"/user/"+id;
            String url = "http://user-service/user/"+id;
    
            log.info(url);
    
            String forObject = restTemplate.getForObject(url, String.class);
    
            log.info(forObject);
    
            return forObject;
        }
    
        public String defalutFallback(){
            return "默认提示：对不起，网络太拥挤了！";
        }

# 四、熔断演示 #

先访问 [http://localhost:8080/consumer/2][http_localhost_8080_consumer_2]

出现

![20201201012536801.png][]

再连续访问 [http://localhost:8080/consumer/1][http_localhost_8080_consumer_1]

出现

![20201201012611357.png][]

再访问 [http://localhost:8080/consumer/2][http_localhost_8080_consumer_2]

出现

![20201201012706182.png][]

# 五、部分hystrix配置 #

hystrix:
      command:
        default:
          execution:
            isolation:
              thread:
                timeoutInMilliseconds: 20000 # 在调用方配置，被该调用方的所有方法的超时时间都是该值，优先级低于下边的指定配置
          circuitBreaker:
            errorThresholdPercentage: 50 # 触发熔断错误比例阀值，默认50%
            sleepWindowInMilliseconds: 10000 #熔断后休眠状态时长，默认值5秒
            requestVolumeThreshold: 10 # 熔断触发最小请求次数，默认值为0

# 六、原理简介 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2E4MEM1MQ_size_16_color_FFFFFF_t_70][]

# 七、代码[传送门][Link 1] #

[http_localhost_8080_consumer_2]: http://localhost:8080/consumer/2
[20201201012536801.png]: /images/20221120/474ce628364243a78e21d221a13459f7.png
[http_localhost_8080_consumer_1]: http://localhost:8080/consumer/1
[20201201012611357.png]: https://img-blog.csdnimg.cn/20201201012611357.png
[20201201012706182.png]: https://img-blog.csdnimg.cn/20201201012706182.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2E4MEM1MQ_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20201201013106264.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2E4MEM1MQ==,size_16,color_FFFFFF,t_70
[Link 1]: https://gitee.com/wayneBatman007/spring-cloud-demo