public class CustomerCommand extends HystrixCommand<Object> {

    private RestTemplate restTemplate;



    public CustomerCommand(RestTemplate restTemplate) {
        super(
                Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("study-hystrix"))
                        .andCommandKey(HystrixCommandKey.Factory.asKey("CustomerController"))
                        .andThreadPoolKey(HystrixThreadPoolKey.Factory.asKey("studyThreadPool"))
                        .andCommandPropertiesDefaults(HystrixCommandProperties.Setter()
                                .withExecutionTimeoutInMilliseconds(100).withCircuitBreakerSleepWindowInMilliseconds(5000))
                                .andThreadPoolPropertiesDefaults(HystrixThreadPoolProperties.Setter()
                                        .withCoreSize(1)
                                        .withMaxQueueSize(2))

        );
        this.restTemplate = restTemplate;
    }

    @Override
    protected Object run() throws Exception {
            //调用我们期望调用的方法
        System.out.println("当前线程是："+Thread.currentThread().getName());
        return restTemplate.getForObject("http://HELLOSERVER/index",String.class);
    }

    @Override
    protected Object getFallback() {
        System.out.println("服务降级了");
        return "服务降级了";
    }
}

@SpringBootApplication
@EnableEurekaClient
@RestController
public class SpringCloudHystrixApplication {

    @Autowired
    private RestTemplate restTemplate;

    @Autowired
    private LoadBalancerClient loadBalancerClient;

    public static void main(String[] args) {
        SpringApplication.run(SpringCloudHystrixApplication.class, args);
    }


    @GetMapping("index")
    public Object index(){
        return new CustomerCommand(restTemplate).execute();
    }

 @HystrixCommand(fallbackMethod = "callTimeOutFallback",
            threadPoolProperties = {@HystrixProperty(name = "coreSize",value = "1"),
                    @HystrixProperty(name = "queueSizeRejectionThreshold",value = "1"),
                    },
            commandProperties = {@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "100")})
    @GetMapping("index2")
    public Object index2(){
        return restTemplate.getForObject("http://HELLOSERVER/index",String.class);
    }

    public Object callTimeOutFallback(){
        return "请求index2降级";
    }



}

 <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>