转载

spring cloud 2.x版本 Ribbon服务发现教程(内含集成Hystrix熔断机制)

本文基于前两篇文章eureka-server和eureka-client的实现。参考

eureka-server
eureka-client

1 Ribbon工程搭建

1.1 创建spring boot工程：eureka-ribbon

1.2 pom.xml所需要依赖的jar包

<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-ribbon</artifactId>
</dependency>
复制代码

1.3 添加application.yml信息

application.yml

spring:
  application:
    name: eureka-ribbon
server:
  port: 8901

eureka:
  instance:
    hostname: localhost
    lease-renewal-interval-in-seconds: 5
    lease-expiration-duration-in-seconds: 10
  client:
    service-url:
      defaultZone: http://eureka1.server.com:8701/eureka/,http://eureka2.server.com:8702/eureka/,http://eureka3.server.com:8703/eureka/
复制代码

1.4 启动类添加相关注解@EnableDiscoveryClient

package spring.cloud.demo.eurekaribbon;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;

@EnableDiscoveryClient
@SpringBootApplication
public class EurekaRibbonApplication {

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

}
复制代码

@EnableDiscoveryClient启动eureka服务发现相关配置

1.5 创建应用配置类RestTemplateConfig

package spring.cloud.demo.eurekaribbon.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

/**
 * @auther: maomao
 * @DateT: 2019-09-17
 */
@Configuration
public class RestTemplateConfig {

    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

}
复制代码

@LoadBalanced 实现负载均衡

1.6 创建EurekaRibbonService

package spring.cloud.demo.eurekaribbon.service;

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

/**
 * @auther: maomao
 * @DateT: 2019-09-17
 */
@Service
public class EurekaRibbonService {

    @Autowired
    RestTemplate restTemplate;

    public String sayHello() {
        String message;
        try {
            message = restTemplate.getForObject("http://eureka-client/info", String.class);
        } catch (RestClientException e) {
            message = e.getMessage();
        }
        return message;
    }
}
复制代码

http://eureka-client/info , 其中eureka-client为服务提供者对应的spring.application.name

1.7 创建服务消费者控制类:EurekaRibbonConntroller

package spring.cloud.demo.eurekaribbon.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import spring.cloud.demo.eurekaribbon.service.EurekaRibbonService;

/**
 * @auther: maomao
 * @DateT: 2019-09-17
 */
@RestController
public class EurekaRibbonConntroller {

    @Autowired
    private EurekaRibbonService eurekaRibbonService;

    @RequestMapping("/syaHello")
    public String syaHello() {
        String message = eurekaRibbonService.sayHello();
        return "ribbon result: " + message;
    }
}
复制代码

1.8 启动服务

前题保证eureka-server和eureka-client已经正常启动。然后启动eureka-ribbon服务。在浏览器输入http://localhost:8901/syaHello，如下图所示：

spring cloud 2.x版本 Ribbon服务发现教程(内含集成Hystrix熔断机制)

多次刷新后可以看到浏览器显示的是结果中端口是变化的。

结语

至此，一个简单的单点Ribbon服务消费者就搭建完成。

彩蛋

Hystrix Ribbon实现断路器

场景：假如在生产环境中，访问量很大的情况下，那么就会产生很多请求阻塞的情况，然后服务器的内存消耗就会陡增，严重情况下会导致系统的崩溃，也就是常见的雪崩。为了避免这种情况，熔断保护机制就迎刃而生。在访问不通的情况下，要及时作出响应，而不是等待超时。

pom.xml增加相关依赖

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>
复制代码

修改EurekaRibbonService

package spring.cloud.demo.eurekaribbon.service;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestClientException;
import org.springframework.web.client.RestTemplate;

/**
 * @auther: maomao
 * @DateT: 2019-09-17
 */
@Service
public class EurekaRibbonService {

    @Autowired
    RestTemplate restTemplate;

    @HystrixCommand(
            commandProperties = {
            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "1000"),
            @HystrixProperty(name = "execution.isolation.strategy",value = "THREAD")},
            fallbackMethod = "syaHelloFailure")
    public String sayHello() {
        String message;
        try {
            message = restTemplate.getForObject("http://eureka-client/info", String.class);
        } catch (RestClientException e) {
            message = e.getMessage();
        }
        return message;
    }

    public String syaHelloFailure() {
        System.out.println("error come in ");
        String message = "网络繁忙， 请稍后再试";
        return message;
    }
}
复制代码