项目状态：维护中...

loadbalancer目前在springcloudcommons下

简单的说就是将用户的请求平摊的分配到多个服务上，从而达到系统的HA（高可用），常见的负载均衡有软件Nginx，LVS，硬件 F5等

Spring Cloud LoadBalancer是由SpringCloud官方提供的一个开源的、简单易用的 客户端负载均衡器，它包含在SpringCloud-commons中用它来替换了以前的Ribbon组件。相比较于Ribbon，SpringCloud LoadBalancer不仅能够支持RestTemplate，还支持WebClient（WeClient是Spring Web Flux中提供的功能，可以实现响应式异步请求）

看到两个service已注册成功， 但是consul的key/value之前配置未进行持久化保存，已经不存在

• 新建mydata文件夹
• 新建文件consul start.bat后缀为.bat

@echo.服务启动......  
@echo off  
@sc create Consul binpath= "D:\devSoft\consul_1.17.0_windows_386\consul.exe agent -server -ui -bind=127.0.0.1 -client=0.0.0.0 -bootstrap-expect  1  -data-dir D:\devSoft\consul_1.17.0_windows_386\mydata   "
@net start Consul
@sc config Consul start= AUTO  
@echo.Consul start is OK......success
@pause

consul agent -server -config-dir=E:/consul/config -data-dir=E:/consul/data -bind=127.0.0.1 -bootstrap-expect=1 -ui

• cloud-payment-service-8001:http://localhost:8001/pay/get/info
• cloud-payment-service-8002:http://localhost:8002/pay/get/info

<!--loadbalancer-->
<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>

cloud-payment-service 要与consul上注册名称一致。

@RestController
public class OrderController
{//public static final String PaymentSrv_URL = "http://localhost:8001";//先写死，硬编码public static final String PaymentSrv_URL = "http://cloud-payment-service";//服务注册中心上的微服务名称@Autowiredprivate RestTemplate restTemplate;/*** 一般情况下，通过浏览器的地址栏输入url，发送的只能是get请求* 我们模拟消费者发送get请求，but底层调用post方法，客户端消费者参数PayDTO可以不添加@RequestBody* @param payDTO* @return*/@GetMapping("/consumer/pay/add")public ResultData addOrder(PayDTO payDTO){return restTemplate.postForObject(PaymentSrv_URL + "/pay/add",payDTO,ResultData.class);}@GetMapping("/consumer/pay/get/{id}")public ResultData getPayInfo(@PathVariable Integer id){return restTemplate.getForObject(PaymentSrv_URL + "/pay/get/"+id, ResultData.class, id);}@GetMapping(value = "/consumer/pay/get/info")private String getInfoByConsul(){return restTemplate.getForObject(PaymentSrv_URL + "/pay/get/info", String.class);}
}

@Resource
private DiscoveryClient discoveryClient;
@GetMapping("/consumer/discovery")
public String discovery()
{List<String> services = discoveryClient.getServices();for (String element : services) {System.out.println(element);}System.out.println("===================================");List<ServiceInstance> instances = discoveryClient.getInstances("cloud-payment-service");for (ServiceInstance element : instances) {System.out.println(element.getServiceId()+"\t"+element.getHost()+"\t"+element.getPort()+"\t"+element.getUri());}return instances.get(0).getServiceId()+":"+instances.get(0).getPort();
}

默认两种算法轮询和随机

public class RoundRobinLoadBalancer implementsReactorServiceInstanceLoadBalancer

从默认的轮询，切换为 随机算法，修改RestTemplateConfig

/*** LoadBalancer默认轮询算法切换随机算法* @LoadBalancerClient   @Bean*/
@Configuration
@LoadBalancerClient(//下面的value值大小写一定要和consul里面的名字一样，必须一样value = "cloud-payment-service",configuration = RestTemplateConfig.class)
public class RestTemplateConfig
{@Bean@LoadBalanced //使用@LoadBalanced注解赋予RestTemplate负载均衡的能力public RestTemplate restTemplate(){return new RestTemplate();}@BeanReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment,LoadBalancerClientFactory loadBalancerClientFactory) {String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);return new RandomLoadBalancer(loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), name);}
}

@LoadBalancerClient(name = "my-service", configuration = MyServiceLoadBalancerConfig.class)  
public class MyServiceConfiguration {  // 这里可以包含一些针对my-service的特定配置  
}  @Configuration  
public class MyServiceLoadBalancerConfig {  @Bean  public IRule myCustomRule() {  // 返回一个自定义的负载均衡规则  return new MyCustomRule();  }  
}