一个很简单的SpringCloud项目,集成Feign、Hystrix

Feign的功能:这是个消费者,根据服务注册在Eureka的ID去找到该服务,并调用接口
Hystrix的功能:熔断器,假如A服务需要调用B服务的/cities接口获取数据,那就在A服务的controller里声明@HystrixCommand,如果B服务的/cities接口挂了,就返回一个自定义的值

项目结构

[root@node01 cloud]# tree weather/
weather/
├── Application.java    #主程序启动入口
├── controller
│   ├── CityController.java   #控制路由,比如访问127.0.0.1:8080/cities, 这里调用cityClient方法
└── service
    └── CityClient.java        #具体方法的实现,这里就具体实现cityClient方法(interface)

Application.java

package com.waylau.spring.cloud.weather;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;  #引入熔断器
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;   #让eureka能发现自己
import org.springframework.cloud.netflix.feign.EnableFeignClients;     #引入feign

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients    #声明这个程序引入FeignClient
@EnableCircuitBreaker  #声明这个程序引入熔断器
public class Application {

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

controller/CityController.java

package com.waylau.spring.cloud.weather.controller;

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

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.waylau.spring.cloud.weather.service.CityClient;  #引用service/CityClient.java

@RestController
public class CityController {
        @Autowired
        private CityClient cityClient;

        @GetMapping("/cities")  #控制路由,比如访问127.0.0.1:8080/cities
        @HystrixCommand(fallbackMethod="defaultCities") #给另外一个服务设置hystrix熔断器,并声明fallbackMethod(回调方法)假如另外一个服务挂了,就调用defaultCities方法
        public String listCity() {
                // 通过Feign客户端来查找
                String body = cityClient.listCity();   #调用service里CityClient.java的cityClient方法,获取城市数据
                return body;                           #返回,访问127.0.0.1:8080/cities就能返回城市数据
        }

        public String defaultCities() {
                return "City Data Server is down!";
        }
}

service/CityClient.java(消费者)

用Feign去另一个接口获取数据

package com.waylau.spring.cloud.weather.service;

import org.springframework.cloud.netflix.feign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;

@FeignClient("msa-weather-city") #msa-weather-city是msa-weather-city服务注册到eureka的ID,通过这个ID就能访问到msa-weather-city微服务
public interface CityClient {

        @GetMapping("/cities")    #调用msa-weather-city微服务里的/cities接口
        String listCity();        #调用msa-weather-city微服务里的/cities接口里的listCity()方法
}

application.properties

spring.application.name: micro-weather-eureka-client-feign-hystrix

eureka.client.serviceUrl.defaultZone: http://localhost:8761/eureka/

feign.client.config.feignName.connectTimeout: 5000
feign.client.config.feignName.readTimeout: 5000

测试,条件为另一个服务可用时,我们是能调用的

测试.条件为另一个服务不可以时,我们是不能调用的,所以fallback