Ribbon使用Hystrix

1、导入依赖spring-cloud-starter-hystrix

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

2、消费启动类开启@EnableCircuitBreaker

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.cloud.netflix.ribbon.RibbonClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
//开启Ribbon
@RibbonClient(name="cloud-producer")
//启动断路器支持(Hystrix)
@EnableCircuitBreaker
public class RibbonConsumerApplication {

    @Bean
    @LoadBalanced //负载均衡
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

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

}

3、TestService——设置断路器核心类

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.web.client.RestTemplate;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;

@Repository
public class TestService {

    @Autowired
    private RestTemplate restTemplate;

    //设置断路器,当此方法无法应答时(把mima-cloud-producer服务停掉),调用getError方法
    @HystrixCommand(fallbackMethod="getError")
    public String get(String id) {
        System.out.println(Thread.currentThread().getName()+".get before...");
        String result = restTemplate.getForObject("http://cloud-producer/get/"+id, String.class);
        System.out.println(Thread.currentThread().getName()+".get end...result="+result);
        return result;
    }

    public String getError(String id) {
        System.out.println(Thread.currentThread().getName()+"断路器启动");
        return "断路器fallback返回error";
    }
}

4、TestController——测试类

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.robbin.service.TestService;

@RestController
public class TestController {

    @Autowired
    private TestService testService;

    @GetMapping("/ribbon/get/{id}")
    public String get(@PathVariable String id) {
        return testService.get(id);
    }
}

以上代码在cloud-consumer-ribbon-hystrix服务中，模拟远程调用cloud-producer服务。

5、模拟测试
5.1、启动服务
启动cloud-consumer-ribbon-hystrix、cloud-producer服务，保证服务正常。

5.2、正常请求

5.3、服务挂掉请求，触发断路器
把cloud-producer服务关闭，这时http://localhost:8807/ribbon/get/123456请求无法应答，会调用getError方法，触发断路器

5.4、多次请求控制台会打印如下信息：