Hystrix快速入门

1、引入Maven依赖

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

2、启动类使用@EnableCircuitBreaker注解

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;

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

3、使用@HystrixCommand注解，并配置fallbackMethod
@HystrixCommand由名为“javanica”的Netflix contrib库提供。Spring Cloud在连接到Hystrix断路器的代理中使用该注解自动包装Spring bean。断路器计算何时打开和关闭电路，以及在发生故障时应该做什么。

package com.mimaxueyuan.consumer.turbine.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import com.mimaxueyuan.consumer.turbine.service.MyService;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;

@RestController
public class HelloController {

    @Autowired
    private MyService myService;

    /**
     * 模拟id为"ok"时请求成功，其它值让请求休眠5秒超时
     * 
     * @param id
     * @return
     * @author lynch
     */
    @GetMapping("/hello/{id}")
    @HystrixCommand(fallbackMethod = "getError")
    public String hello(@PathVariable String id) {
        if(!"ok".equals(id)) {
            try {
                System.out.println(Thread.currentThread().getName()+":hello before sleep 5s....");
                Thread.sleep(1000 * 5);
                System.out.println(Thread.currentThread().getName()+":hello after sleep 5s....");
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        
        return "请求成功，id=" + id;
    }

    public String getError(String id) {
        System.out.println(Thread.currentThread().getName()+":getError before ....");
        //myService.execute();
        System.out.println("断路器已触发，并作相应的业务处理...");
        System.out.println(Thread.currentThread().getName()+":getError after ....");
        
        return "请求超时，使用断路器返回，id=" + id;
    }
}

4、模拟url请求
4.1、正常请求

4.2、超时请求，使用断路器返回

4.3控制台输出信息

hystrix-HelloController-2:hello before sleep 5s....
HystrixTimer-1:getError before ....
断路器已触发，并作相应的业务处理...
HystrixTimer-1:getError after ....
java.lang.InterruptedException: sleep interrupted
    at java.lang.Thread.sleep(Native Method)
    at com.mimaxueyuan.consumer.turbine.controller.HelloController.hello(HelloController.java:30)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.netflix.hystrix.contrib.javanica.command.MethodExecutionAction.execute(MethodExecutionAction.java:116)
    at com.netflix.hystrix.contrib.javanica.command.MethodExecutionAction.executeWithArgs(MethodExecutionAction.java:93)
    at com.netflix.hystrix.contrib.javanica.command.MethodExecutionAction.execute(MethodExecutionAction.java:78)
    at com.netflix.hystrix.contrib.javanica.command.GenericCommand$1.execute(GenericCommand.java:48)
    at com.netflix.hystrix.contrib.javanica.command.AbstractHystrixCommand.process(AbstractHystrixCommand.java:145)
    at com.netflix.hystrix.contrib.javanica.command.GenericCommand.run(GenericCommand.java:45)
    at com.netflix.hystrix.HystrixCommand$2.call(HystrixCommand.java:302)
    at com.netflix.hystrix.HystrixCommand$2.call(HystrixCommand.java:298)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:46)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.Observable.unsafeSubscribe(Observable.java:10151)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
    at rx.Observable.unsafeSubscribe(Observable.java:10151)
    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
    at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    at rx.Observable.unsafeSubscribe(Observable.java:10151)
    at rx.internal.operators.OperatorSubscribeOn$1.call(OperatorSubscribeOn.java:94)
    at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction$1.call(HystrixContexSchedulerAction.java:56)
    at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction$1.call(HystrixContexSchedulerAction.java:47)
    at com.netflix.hystrix.strategy.concurrency.HystrixContexSchedulerAction.call(HystrixContexSchedulerAction.java:69)
    at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55)
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)