spring cloud（断路器——初学五）

Feign使用Hystrix

　　因为feign已经依赖了hystrix，所以可以直接使用，无需添加再次添加依赖。

　　1、使用@FeignClient注解中的fallback属性指定回调类

package com.daqsoft;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

/**
 * @Description Created by liaoxx on 2017-6-12.
 */
@FeignClient(value = "compute-service", fallback = ComputeClientHystrix.class)
public interface ComputerClient {
    @RequestMapping(method = RequestMethod.GET, value = "/add")
    Integer add(@RequestParam(value = "a") Integer a, @RequestParam(value = "b") Integer b);
}

　　2、创建回调类ComputeClientHystrix，实现@FeignClient的接口，此时实现的方法就是对应@FeignClient接口中映射的fallback函数

package com.daqsoft;

import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestParam;

/**
 * @Description Created by liaoxx on 2017-6-13.
 */
@Component
public class ComputeClientHystrix implements ComputerClient {
    @Override
    public Integer add(@RequestParam(value = "a") Integer a, @RequestParam(value = "b") Integer b) {
        return -1;
    }
}

　　3、web调用

package com.daqsoft;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

/**
 * @Description Created by liaoxx on 2017-6-12.
 */
@RestController
public class CustomController {

    @Autowired
    private ComputerClient computerClient;

    @RequestMapping(value = "/add", method = RequestMethod.GET)
    public Integer add(){
        return computerClient.add(10,20);

    }
}

　　4、启动服务，访问http://localhost:3333/add

　　报错，无法进入回调

　　5、修改配置文件，添加属性

spring.application.name=ribbon-consumer

server.port=3333
#服务注册中心地址
eureka.client.serviceUrl.defaultZone=http://localhost:1111/eureka/

#开启hystrix支持
feign.hystrix.enabled=true

　　6、再次启动服务，访问http://localhost:3333/add （正常访问回调方法）