springcloud微服务(十九) - Hystrix服务端和消费端的服务降级

一、服务端8002服务降级

降级配置：@HystrixCommand

（一）8002存在的问题：

设置自身调用超时时间的峰值，峰值内可以正常运行，超过了需要有兜底的方法处理，做服务降级fallback。

（二）、8002fallback

2.1 主启动类**

添加新注解@EnableHystrix,我们可以看到@EnableCircuitBreaker已经被标注删除线，但是@EnableHystrix集成了@EnableCircuitBreaker注解。

@SpringBootApplication
@EnableDiscoveryClient
@EnableHystrix
public class HystrixPayment8002 {
    public static void main(String[] args)
    {
        SpringApplication.run(HystrixPayment8002.class,args);
    }
}

2.2 在service的类上添加@HystrixCommand注解

@Service
public class HystrixPaymentService {

    public String paymentInfo_ok(Integer id)
    {
        return "线程池："+Thread.currentThread().getName()+"  paymentInfo_ok,id="+id+"\t"+"成功";
    }

    //模拟业务流程长，耗时长
    @HystrixCommand(fallbackMethod = "paymentInfo_timeouthandle",commandProperties = {
        @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value = "3000")
    })
    public String paymentInfo_timeout(Integer id)  {
        int time=5;
        try {
            TimeUnit.SECONDS.sleep(time);
        }catch (InterruptedException e)
        {
            e.printStackTrace();
        }

        return "线程池："+Thread.currentThread().getName()+"  paymentInfo_timeout,id="+id+"\t"+"超时";
    }
    public String paymentInfo_timeouthandle(Integer id)  {

        return "支付系统忙,请稍后再试";
    }
}

注意：回退方法paymentInfo_timeouthandle必须与原方法的参数保持完全一致(参数个数与类型)，否则会报错

com.netflix.hystrix.contrib.javanica.exception.FallbackDefinitionException: fallback method wasn't found

（三）、测试

请求http://127.0.0.1:8002/payment/info/timeout/667

3秒钟后会有收到应答，调用的回退函数生效。

（四）、异常时也会调用回退方法

二、客户端服务降级

（一）一般情况是客户端做服务降级，对客户端做保护

（二）主启动类加注解@EnableHystrix

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@EnableHystrix
public class OpenFeignHystrixOrder80 {
    public static void main(String[] args)
    {
        SpringApplication.run(OpenFeignHystrixOrder80.class,args);
    }
}

（三）业务类加@HystrixCommand注解

@RestController
public class HystrixOrderController {

    @Autowired
    private HystrixPaymentService hystrixPaymentService;

    @GetMapping("/consumer/payment/info/ok/{id}")
    public String paymentInfo_ok(@PathVariable("id") Integer id)
    {
        return hystrixPaymentService.paymentInfo_ok(id);
    }

    //模拟业务流程长，耗时长
    @GetMapping("/consumer/payment/info/timeout/{id}")
    @HystrixCommand(fallbackMethod = "paymentInfo_timeoutFallback",commandProperties = {
            @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value="3000")
    })
    public String paymentInfo_timeout(@PathVariable("id") Integer id)
    {
        return hystrixPaymentService.paymentInfo_timeout(id);
    }
    public String paymentInfo_timeoutFallback(Integer id)
    {
        return "消费端80,支付系统异常，请稍后再试";
    }
}

（四）测试

请求http://127.0.0.1/consumer/payment/info/timeout/667

3秒钟后会有收到应答，调用的回退函数生效。

（五）异常时也会调用回退方法