hystrix实现服务降级，熔断

添加pom

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

一：服务降级
（1）在服务端实现
使用注解@HystrixCommand， 在超时，程序异常的情况下都会使用备选方案

@HystrixCommand(fallbackMethod = "paymentInfo_TimeOutHandler",commandProperties = {
    
    
            @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value="5000")
    })
    public String paymentInfo_TimeOut(Integer id)
    {
    
    
        //int age = 10/0;
        try {
    
     TimeUnit.MILLISECONDS.sleep(13000); } catch (InterruptedException e) {
    
     e.printStackTrace(); }
        return "线程池:  "+Thread.currentThread().getName()+" id:  "+id+"\t"+"O(∩_∩)O哈哈~"+"  耗时(秒): ";
    }
    public String paymentInfo_TimeOutHandler(Integer id)
    {
    
    
        return "线程池:  "+Thread.currentThread().getName()+"  8001系统繁忙或者运行报错，请稍后再试,id:  "+id+"\t"+"o(╥﹏╥)o";
    }

使用了注解后在主启动类激活，添加这个注解

@EnableCircuitBreaker

（2）在客户端实现 80端口（一般在这里实现服务降级）
1.添加配置

feign:
  hystrix:
    enabled: true

2.主启动类加注解

@EnableHystrix

3.业务类

 @Resource
    private PaymentHystrixService paymentHystrixService;

    @GetMapping("/consumer/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id)
    {
    
    
        String result = paymentHystrixService.paymentInfo_OK(id);
        return result;
    }

    @GetMapping("/consumer/payment/hystrix/timeout/{id}")
    @HystrixCommand(fallbackMethod = "paymentTimeOutFallbackMethod",commandProperties = {
    
    
            @HystrixProperty(name="execution.isolation.thread.timeoutInMilliseconds",value="1500")
    })
    //@HystrixCommand
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id)
    {
    
    
       // int age = 10/0;
        String result = paymentHystrixService.paymentInfo_TimeOut(id);
        return result;
    }
    public String paymentTimeOutFallbackMethod(@PathVariable("id") Integer id)
    {
    
    
        return "我是消费者80,对方支付系统繁忙请10秒钟后再试或者自己运行出错请检查自己,o(╥﹏╥)o";
    }

配置全局的降级方法， 在类上面通过这个配置，如果没有专门的方法就调用全局fullback方法

@DefaultProperties(defaultFallback = "payment_Global_FallbackMethod")

解决宕机，同时解决代码混乱的问题

实现我们调用其他微服务的接口，重写接口方法，注意使用 @Component 把类注入到spring

在@FeignClient注解中加上fallback 这样就可以在没有标明降级的情况下也会使用备用方案

@Component
@FeignClient(value = "CLOUD-PROVIDER-HYSTRIX-PAYMENT", fallback = PaymentFallbackService.class)
public interface PaymentHystrixService
{
    
    
    @GetMapping("/payment/hystrix/ok/{id}")
    public String paymentInfo_OK(@PathVariable("id") Integer id);

    @GetMapping("/payment/hystrix/timeout/{id}")
    public String paymentInfo_TimeOut(@PathVariable("id") Integer id);
}

@Component
public class PaymentFallbackService implements PaymentHystrixService
{
    
    
    @Override
    public String paymentInfo_OK(Integer id)
    {
    
    
        return "-----PaymentFallbackService fall back-paymentInfo_OK ,o(╥﹏╥)o";
    }

    @Override
    public String paymentInfo_TimeOut(Integer id)
    {
    
    
        return "-----PaymentFallbackService fall back-paymentInfo_TimeOut ,o(╥﹏╥)o";
    }
}

服务熔断

@HystrixCommand(fallbackMethod = "paymentCircuitBreaker_fallback",commandProperties = {
    
    
            @HystrixProperty(name = "circuitBreaker.enabled",value = "true"),// 是否开启断路器
            @HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",value = "10"),// 请求次数
            @HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds",value = "10000"), // 时间窗口期
            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage",value = "60"),// 失败率达到多少后跳闸
    })
    public String paymentCircuitBreaker(@PathVariable("id") Integer id)
    {
    
    
        if(id < 0)
        {
    
    
            throw new RuntimeException("******id 不能负数");
        }
        String serialNumber = IdUtil.simpleUUID();

        return Thread.currentThread().getName()+"\t"+"调用成功，流水号: " + serialNumber;
    }
    public String paymentCircuitBreaker_fallback(@PathVariable("id") Integer id)
    {
    
    
        return "id 不能负数，请稍后再试，/(ㄒoㄒ)/~~   id: " +id;
    }