springcloud alibaba之Nacos

服务发现的领域模型

• NameSpace：实线隔离，默认public
• Group:不同服务可以分到一个组，默认DEFAULT_GROUP
• service：微服务
• cluster：对指定微服务的一个虚拟划分，默认Default
• instance：微服务实例

 ribboon的父子上下文重叠，ribbon的懒加载。

自定义权重策略

import com.alibaba.nacos.api.exception.NacosException;
import com.alibaba.nacos.api.naming.NamingService;
import com.alibaba.nacos.api.naming.pojo.Instance;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.alibaba.nacos.NacosDiscoveryProperties;
import org.springframework.cloud.alibaba.nacos.ribbon.NacosServer;

@Slf4j
public class NacosWeightedRule extends AbstractLoadBalancerRule {
    @Autowired
    private NacosDiscoveryProperties nacosDiscoveryProperties;
    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {
        // 读取配置文件，并初始化NacosWeightedRule
    }

    @Override
    public Server choose(Object key) {
        try {
            BaseLoadBalancer loadBalancer = (BaseLoadBalancer) this.getLoadBalancer();
//        log.info("lb = {}", loadBalancer);

            // 想要请求的微服务的名称
            String name = loadBalancer.getName();

            // 拿到服务发现的相关API
            NamingService namingService = nacosDiscoveryProperties.namingServiceInstance();

            // nacos client自动通过基于权重的负载均衡算法，给我们选择一个实例。
            Instance instance = namingService.selectOneHealthyInstance(name);

            log.info("选择的实例是：port = {}, instance = {}", instance.getPort(), instance);
            return new NacosServer(instance);
        } catch (NacosException e) {
            return null;
        }
    }
}

// spring cloud commons --> 定义了标准
// spring cloud loadbalancer --> 没有权重

自定义同集群策略

import com.alibaba.nacos.api.exception.NacosException;
import com.alibaba.nacos.api.naming.NamingService;
import com.alibaba.nacos.api.naming.pojo.Instance;
import com.alibaba.nacos.client.naming.core.Balancer;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.BaseLoadBalancer;
import com.netflix.loadbalancer.Server;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.alibaba.nacos.NacosDiscoveryProperties;
import org.springframework.cloud.alibaba.nacos.ribbon.NacosServer;
import org.springframework.util.CollectionUtils;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;

@Slf4j
public class NacosSameClusterWeightedRule extends AbstractLoadBalancerRule {
    @Autowired
    private NacosDiscoveryProperties nacosDiscoveryProperties;

    @Override
    public void initWithNiwsConfig(IClientConfig clientConfig) {

    }

    @Override
    public Server choose(Object key) {
        try {
            // 拿到配置文件中的集群名称 BJ
            String clusterName = nacosDiscoveryProperties.getClusterName();

            BaseLoadBalancer loadBalancer = (BaseLoadBalancer) this.getLoadBalancer();
            // 想要请求的微服务的名称
            String name = loadBalancer.getName();

            // 拿到服务发现的相关API
            NamingService namingService = nacosDiscoveryProperties.namingServiceInstance();

            // 1. 找到指定服务的所有实例 A
            List instances = namingService.selectInstances(name, true);

            // 2. 过滤出相同集群下的所有实例 B
            List sameClusterInstances = instances.stream()
                .filter(instance -> Objects.equals(instance.getClusterName(), clusterName))
                .collect(Collectors.toList());

            // 3. 如果B是空，就用A
            List instancesToBeChosen = new ArrayList<>();
            if (CollectionUtils.isEmpty(sameClusterInstances)) {
                instancesToBeChosen = instances;
                log.warn("发生跨集群的调用, name = {}, clusterName = {}, instances = {}",
                    name,
                    clusterName,
                    instances
                );
            } else {
                instancesToBeChosen = sameClusterInstances;
            }
            // 4. 基于权重的负载均衡算法，返回1个实例
            Instance instance = ExtendBalancer.getHostByRandomWeight2(instancesToBeChosen);
            log.info("选择的实例是 port = {}, instance = {}", instance.getPort(), instance);

            return new NacosServer(instance);
        } catch (NacosException e) {
            log.error("发生异常了", e);
            return null;
        }
    }
}

class ExtendBalancer extends Balancer {
    public static Instance getHostByRandomWeight2(List hosts) {
        return getHostByRandomWeight(hosts);
    }
}