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

桃扇骨 2023-10-06 20:56 14阅读 0赞

## 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 主启动类激活

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][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][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。

### （五）异常时也会调用回退方法 ###

[http_127.0.0.1_8002_payment_info_timeout_667]: http://127.0.0.1:8002/payment/info/timeout/667