SpringCloud之Hystrix

Hystrix是一种保护机制，即熔断器。服务的消费者请求服务担心返回异常，所以需要在消费者一方配置自己的降级处理，所以操作在消费者一方。

1、引入Hystix依赖


    org.springframework.cloud
    spring-cloud-starter-netflix-hystrix

2、开启服务降级

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class ConsumerApp {
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
    public static void main(String[] args){
        SpringApplication.run(ConsumerApp.class,args);
    }
}

3、重新写方法因为默认使用了Hystrix，所以要处理一下方法，如果失败之后返回信息

     
    @GetMapping("/student/{ids}")
    @HystrixCommand(fallbackMethod = "studentsFallBack")
    public List student(@PathVariable("ids") List ids){
        List list = new ArrayList<>();
        ids.forEach(id->{
            //远程调用，更改路径（需要开启负载均衡）
            String url = "http://user-service/student/"+id;
            Student student = restTemplate.getForObject(url, Student.class);
            list.add(student);
        });
        return list;
    }

    
    public List studentsFallBack(@PathVariable("ids") List ids){
        List list = new ArrayList<>();
        for(Integer id : ids){
            Student student = new Student();
            student.setName("请求超时！");
            list.add(student);
        }
        return list;
    }

4、改造user-service 为了能够模拟超时，需要改造一下user-service，让其返回结果慢一点返回

    
    @GetMapping("/student/{id}")
    public Student student(@PathVariable("id") int id){
        try {
            Thread.sleep(2000L);
        }catch (InterruptedException e){
            e.printStackTrace();
        }
        return studentService.getById(id);
    }

5、同步更新配置文件性能都改为单台服务进行测试

eureka-server：

server:
  port: 10086
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka/
spring:
  application:
    name: eureka-server

user-service：

eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka/
    instance:
      instance-id: ${spring.application.name}:${server.port}

consumer-demo：

server:
  port: 9000
spring:
  application:
    name: consumer-demo
eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:10086/eureka/
user-service:
  ribbon:
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule

SpringCloud之Hystrix

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