Spring Cloud实战04-- 负载均衡Ribbon

我会带着你远行 2024-04-17 05:48 8阅读 0赞

# 负载均衡Ribbon #

实际环境中，我们往往会开启很多个bubbletg-provider的集群。此时我们获取的服务列表中就会有多个，到底该访问哪一个呢？

一般这种情况下我们就需要编写负载均衡算法，在多个实例列表中进行选择。

不过Eureka中已经帮我们集成了负载均衡组件：Ribbon，简单修改代码即可使用。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70]

### 启动两个服务实例 ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 1]  
Eureka监控面板：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 2]

### 开启负载均衡 ###

因为Eureka中已经集成了Ribbon，所以我们无需引入新的依赖，直接修改代码。

修改bubbletg-consumer的引导类，在RestTemplate的配置方法上添加`@LoadBalanced`注解：

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

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 3]修改调用方式，不再手动获取ip和端口，而是直接通过服务名称调用：

@Controller
    @RequestMapping("consumer/user")
    public class UserController {
    
        @Autowired
        private RestTemplate restTemplate;
    
        //@Autowired
        //private DiscoveryClient discoveryClient; // 注入discoveryClient，通过该客户端获取服务列表
    
        @GetMapping
        @ResponseBody
        public User queryUserById(@RequestParam("id") Long id){
            // 通过client获取服务提供方的服务列表，这里我们只有一个
            // ServiceInstance instance = discoveryClient.getInstances("service-provider").get(0);
            String baseUrl = "http://service-provider/user/" + id;
            User user = this.restTemplate.getForObject(baseUrl, User.class);
            return user;
        }
    
    }

访问页面，查看结果：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 4]

### 负载均衡策略 ###

Ribbon默认的负载均衡策略是简单的轮询，我们可以测试一下：

package cn.bubbletg.service;
    
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.test.context.SpringBootTest;
    import org.springframework.cloud.client.ServiceInstance;
    import org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient;
    import org.springframework.test.context.junit4.SpringRunner;
    
    /**
     * @author www.bubbletg.cn * BubbleTg
     * @version 1.0
     * @date 2019/8/24 1:00
     */
    @RunWith(SpringRunner.class)
    @SpringBootTest(classes = ServiceConsumerApplication.class)
    public class LoadBalanceTest {
    
        @Autowired
        private RibbonLoadBalancerClient client;
    
        @Test
        public void testLoadBalance(){
            for (int i = 0; i < 100; i++) {
                ServiceInstance instance = this.client.choose("service-provider");
                System.out.println(instance.getHost() + ":" +instance.getPort());
            }
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 5]  
我们是否可以修改负载均衡的策略呢？  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 6]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 7]![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 8]![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 9]SpringBoot也帮我们提供了修改负载均衡规则的配置入口，在bubbletg-consumer的application.yml中添加如下配置：

server:
      port: 80
    spring:
      application:
        name: service-consumer
    eureka:
      client:
        service-url:
          defaultZone: http://127.0.0.1:10086/eureka
    service-provider:
      ribbon:
        NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule

格式是：`{服务名称}.ribbon.NFLoadBalancerRuleClassName`，值就是IRule的实现类。

再次测试：，发现结果变成了随机：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 10]

以上即是负载均衡实战了。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/11/863edc1b6ec14c96a0fc69a341be25f9.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/11/f594a34ed06d426f955938ed54ff7813.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 2]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/11/282917ad71824a1dabd12ce31a25b580.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 3]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/11/54c3e3d8c80e44ae830897ebddb8bd8d.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 6]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/11/bc877bb5146e4a05b82c23837fb6f2a7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 7]: https://img-blog.csdnimg.cn/2019082401053435.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0_size_16_color_FFFFFF_t_70 8]: https://img-blog.csdnimg.cn/20190824010551206.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2NTcwNDY0,size_16,color_FFFFFF,t_70
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