手动创建负载均衡器

「爱情、让人受尽委屈。」 2023-02-25 13:30 1阅读 0赞

## SpringCloud视频教程： ##

[https://ke.qq.com/course/2805647?tuin=a3e3fb1&from\_uin=171851697&from=1000201007][https_ke.qq.com_course_2805647_tuin_a3e3fb1_from_uin_171851697_from_1000201007]

## **个人博客纯净版** ##

[http://www.51ufo.cn/%E5%BE%AE%E6%9C%8D%E5%8A%A1/%E5%88%86%E5%B8%83%E5%BC%8F/2020/07/10/SpringCloud%E5%85%A5%E9%97%A85-%E6%89%8B%E5%8A%A8%E5%88%9B%E5%BB%BA%E8%B4%9F%E8%BD%BD%E5%9D%87%E8%A1%A1%E5%99%A8.html][http_www.51ufo.cn_E5_BE_AE_E6_9C_8D_E5_8A_A1_E5_88_86_E5_B8_83_E5_BC_8F_2020_07_10_SpringCloud_E5_85_A5_E9_97_A85-_E6_89_8B_E5_8A_A8_E5_88_9B_E5_BB_BA_E8_B4_9F_E8_BD_BD_E5_9D_87_E8_A1_A1_E5_99_A8.html]

本文代码git地址 [https://gitee.com/xmingtx/springcloud-lesson.git][https_gitee.com_xmingtx_springcloud-lesson.git]

负载均衡常用的方式有轮询模式、随机模式等等，下面我们来实现一下，在consumer-ribbon服务添加如下代码：

@Component
    public class LoadBalancer {
    
        AtomicInteger counter = new AtomicInteger(0);
    
        /**
         * 轮询模式
         * @param instances
         * @return
         */
        public ServiceInstance getInstanceByCycle(List<ServiceInstance> instances){
            int index = counter.incrementAndGet() % 2;
            return instances.get(index);
        }
    
        /**
         * 随机模式
         * @param instances
         * @return
         */
        public ServiceInstance getInstanceByRandom(List<ServiceInstance> instances){
            int index = new Random().nextInt(instances.size());
            return instances.get(index);
        }
    }

启动两个eureka-client-provider服务，端口分别为8080和8081，Eureka注册中心存在两个实例，如下：

![ribbon1.png][]

修改消费者服务consumer-ribbon的HelloController，代码如下：

@RestController
    public class HelloController {
    
        @Autowired
        private DiscoveryClient discoveryClient;
    
        @Autowired
        private RestTemplate restTemplate;
    
        @Autowired
        private LoadBalancer balancer;
    
        @GetMapping(value = "/hello")
        public String hello(@RequestParam String name) {
            List<ServiceInstance> instances = discoveryClient.getInstances("eureka-client-provider");
            ServiceInstance instance = balancer.getInstanceByCycle(instances);
            return restTemplate.getForObject(instance.getUri() + "/hello?name=" + name, String.class);
        }
    }

启动消费者服务，在浏览器访问http://localhost:8090/hello?name=xiaoming，返回结果轮序交替，如下：

hello, xiaoming, 我是服务提供者:端口为：8080

hello, xiaoming, 我是服务提供者:端口为：8081

将消费者服务中改为随机模式调用，生产者服务则被随机调到。

[https_ke.qq.com_course_2805647_tuin_a3e3fb1_from_uin_171851697_from_1000201007]: https://ke.qq.com/course/2805647?tuin=a3e3fb1&from_uin=171851697&from=1000201007
[http_www.51ufo.cn_E5_BE_AE_E6_9C_8D_E5_8A_A1_E5_88_86_E5_B8_83_E5_BC_8F_2020_07_10_SpringCloud_E5_85_A5_E9_97_A85-_E6_89_8B_E5_8A_A8_E5_88_9B_E5_BB_BA_E8_B4_9F_E8_BD_BD_E5_9D_87_E8_A1_A1_E5_99_A8.html]: http://www.51ufo.cn/%E5%BE%AE%E6%9C%8D%E5%8A%A1/%E5%88%86%E5%B8%83%E5%BC%8F/2020/07/10/SpringCloud%E5%85%A5%E9%97%A85-%E6%89%8B%E5%8A%A8%E5%88%9B%E5%BB%BA%E8%B4%9F%E8%BD%BD%E5%9D%87%E8%A1%A1%E5%99%A8.html
[https_gitee.com_xmingtx_springcloud-lesson.git]: https://gitee.com/xmingtx/springcloud-lesson.git
[ribbon1.png]: /images/20230209/17f43a93dfb94818bb7a609e4e7e244f.png