一、手写随机负载均衡
1、引入依赖
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId>
</dependency><!--引入nacos discovery-->
<dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
2、controller定义
@Resource
private RestTemplate restTemplate;@Resource
private DiscoveryClient discoveryClient;@RequestMapping("/restLoadbalance")
public String manualLoadBlance(){//1、获取order服务urlsList<ServiceInstance> instances = this.discoveryClient.getInstances("order");List<String> urls = instances.stream().map(instance->instance.getUri().toString()+"/order/query").collect(Collectors.toList());//2、随机负载请求int index = ThreadLocalRandom.current().nextInt(urls.size());return this.restTemplate.getForObject(urls.get(index),String.class);
}
二、LoadBalancer
2.1、API
(1)、引入依赖
<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>
(2)、代码
//2、loadbalancer api
@Resource
private LoadBalancerClient loadBalancerClient;@RequestMapping("/loadbanlancerapi")
public String loadBanlancerApi(){ServiceInstance serviceInstance = this.loadBalancerClient.choose("order");return this.restTemplate.getForObject(serviceInstance.getUri().toString()+"/order/query",String.class);
}
2.2、注解
(1)、引入依赖
<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-loadbalancer</artifactId>
</dependency>
(2)、自定义@LoadBanlancer注解得RestTemplate
@Bean
@LoadBalanced // 相当于为restTemplate整合了lb的能力
public RestTemplate restTemplateLoadBalancer(){return new RestTemplate();
}
(3)、controller代码
@Resource
private RestTemplate restTemplateLoadBalancer;
@RequestMapping("/loadbanlanceraop")
public String loadBanlancerAop(){return this.restTemplateLoadBalancer.getForObject("http://order/order/query",String.class);
}
三、默认负载算法
默认轮询负载:RoundRobinLoadBalancer
更改默认负载算法:Cloud Native Applications
(1)、自定义负载算法
public class CustomLoadBalancerConfiguration {@BeanReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment,LoadBalancerClientFactory loadBalancerClientFactory) {String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);return new RandomLoadBalancer(loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class),name);}
}
(2)、启动类增加注解
@SpringBootApplication
@LoadBalancerClients(defaultConfiguration = CustomLoadBalancerConfiguration.class)
public class UserApplicaiton implements ApplicationRunner {
}
四、源码分析
(1)、RestTemplate流程
(2)、LoadBalancerClient#choose(String serviceId)