SpringCloud-负载均衡Ribbon

  一、配置使用

       1、添加依赖（该依赖包含在eureka-client依赖中）

<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-netflix-ribbon</artifactId></dependency>

        2、在RestTemplate上添加@LoadBalanced注解

@Configuration
public class ApplicationContextConfig {@Bean@LoadBalancedpublic RestTemplate getRestTemplate(){return new RestTemplate();}
}

  二、IRule替换负载策略

        以随机为例

        1、添加配置类（注意不要放到@ComponentScan所能扫描到的包下）

@Configuration
public class MyStyleRule {@Beanpublic IRule myRule(){/*** 定义为随机*/return new RandomRule();}
}

       2、在启动类上添加注解

              @RibbonClient(name = "CLOUD-PAYMENT-SERVICE",configuration = MyStyleRule.class)

             name：为服务注册名称

             configuration：为策略类

      3、自定义实现轮询策略

          声明接口

public interface LoadBalancer {ServiceInstance instances(List<ServiceInstance> serviceInstances);
}

         实现接口

@Component
public class MyLb implements LoadBalancer
{private AtomicInteger atomicInteger = new AtomicInteger(0);public final int getAndIncremant(){int current;int next;do{current = this.atomicInteger.get();//Integer.MAX_VALUE=2147483647next = current >= Integer.MAX_VALUE ? 0 : current +1 ;}while(!this.atomicInteger.compareAndSet(current,next));return next;};@Overridepublic ServiceInstance instances(List<ServiceInstance> serviceInstances) {int index = getAndIncremant() % serviceInstances.size();return serviceInstances.get(index);}
}

       测试代码

    @Resourceprivate RestTemplate restTemplate;@Resourceprivate LoadBalancer loadBalancer;@Resourceprivate DiscoveryClient discoveryClient;@GetMapping("/consumer/payment/lb")public String getPaymentLB(){List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");if(instances == null || instances.size() <= 0){return null;}else{ServiceInstance serviceInstance = loadBalancer.instances(instances);URI uri = serviceInstance.getUri();return restTemplate.getForObject(uri+"/payment/lb",String.class);}}