1. -loadbalancer-2.3.0.jar 定制网站是负载均衡的祖师爷

其中gateway集成了ribbon; 和ribbon也有集成。定制网站最终达到一个结果，在ribbon定制网站中维护这一个列表，ancos定制网站服务发现的列表，定制网站做负载均衡，注意是ribbon定制网站中维护这这个列表，定制网站并不是复杂均衡的时候采取和nacos交互。
如果服务有变化，这个列表也会做相应的调整。

2 . 最顶级的接口ILoadBalancer.java

所有的实现类均要实现此接口，比如： DynamicServerListLoadBalancer.java

/** * Interface that defines the operations for a software loadbalancer. A typical * loadbalancer minimally need a set of servers to loadbalance for, a method to * mark a particular server to be out of rotation and a call that will choose a * server from the existing list of server. *  * 负载均衡的顶级接口 * @author stonse *  */public interface ILoadBalancer {	/**	 * Initial list of servers.	 * This API also serves to add additional ones at a later time	 * The same logical server (host:port) could essentially be added multiple times	 * (helpful in cases where you want to give more "weightage" perhaps ..)	 * 	 * @param newServers new servers to add	 * 添加服务器到这个列表中List<Server> newServers	 */	public void addServers(List<Server> newServers);		/**	 * Choose a server from load balancer.	 * 	 * @param key An object that the load balancer may use to determine which server to return. null if 	 *         the load balancer does not use this parameter.	 * @return server chosen	 * 从List<Server> newServers中选择一个服务器作为次轮的负载服务器	 */	public Server chooseServer(Object key);		/**	 * To be called by the clients of the load balancer to notify that a Server is down	 * else, the LB will think its still Alive until the next Ping cycle - potentially	 * (assuming that the LB Impl does a ping)	 * 	 * @param server Server to mark as down	 * 标记此服务为下线（关闭）状态。	 */	public void markServerDown(Server server);		/**	 * @deprecated 2016-01-20 This method is deprecated in favor of the	 * cleaner {@link #getReachableServers} (equivalent to availableOnly=true)	 * and {@link #getAllServers} API (equivalent to availableOnly=false).	 *	 * Get the current list of servers.	 * 获取当前服务器列表	 *	 * @param availableOnly if true, only live and available servers should be returned	 * 如果为true则返回活着并且可用的服务器列表	 */	@Deprecated	public List<Server> getServerList(boolean availableOnly);	/**	 * @return Only the servers that are up and reachable.	 * 返回可用的serer列表     */    public List<Server> getReachableServers();    /**     * @return All known servers, both reachable and unreachable.     * 获取所以的server列表，可用不可用的均可以获得。     */	public List<Server> getAllServers();}1
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有了这个接口我们可以对持有服务列表的list进行任何操作。整理架构建立了。

3. 此类是对服务列表进行更新，比如服务的上线，下线等。

DynamicServerListLoadBalancer.java 类是ribbon的自己实现的。

负载均衡在ribbon中的自我实现策略，默认为轮训，我们可以按自己的需求自己实现即可。

4. ServerList.java

此类是ribbon持有服务列表的接口类，其他任何三方的服务注册与发现中心可以实现它，比如此处我们使用的是nacos所谓服务发现与注册中心，则alibaba就实现了这个接口NacosServerList.java 就是对这个接口的实现。

因此，项目需要引入nacos的依赖。

5. NacosServerList.java

NacosServerList.java 和nacos进行通讯，可以对其服务的状态进行感知进而进行
下面看源码：

/* * Copyright 2013-2018 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package com.alibaba.cloud.nacos.ribbon;import java.util.ArrayList;import java.util.List;import com.alibaba.cloud.nacos.NacosDiscoveryProperties;import com.alibaba.nacos.api.naming.pojo.Instance;import com.alibaba.nacos.client.naming.utils.CollectionUtils;import com.netflix.client.config.IClientConfig;import com.netflix.loadbalancer.AbstractServerList;/** * @author xiaojing * @author renhaojun */public class NacosServerList extends AbstractServerList<NacosServer> {	private NacosDiscoveryProperties discoveryProperties;	private String serviceId;	public NacosServerList(NacosDiscoveryProperties discoveryProperties) {		this.discoveryProperties = discoveryProperties;	}	@Override	public List<NacosServer> getInitialListOfServers() {		return getServers();	}	@Override	public List<NacosServer> getUpdatedListOfServers() {		return getServers();	}	private List<NacosServer> getServers() {		try {			String group = discoveryProperties.getGroup();			List<Instance> instances = discoveryProperties.namingServiceInstance()					.selectInstances(serviceId, group, true);			return instancesToServerList(instances);		}		catch (Exception e) {			throw new IllegalStateException(					"Can not get service instances from nacos, serviceId=" + serviceId,					e);		}	}	private List<NacosServer> instancesToServerList(List<Instance> instances) {		List<NacosServer> result = new ArrayList<>();		if (CollectionUtils.isEmpty(instances)) {			return result;		}		for (Instance instance : instances) {			result.add(new NacosServer(instance));		}		return result;	}	public String getServiceId() {		return serviceId;	}	@Override	public void initWithNiwsConfig(IClientConfig iClientConfig) {		this.serviceId = iClientConfig.getClientName();	}}1
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更新服务列表。
调用：

@Override	public List<NacosServer> getUpdatedListOfServers() {		return getServers();	}1
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调用：

private List<NacosServer> getServers() {		try {			String group = discoveryProperties.getGroup();			List<Instance> instances = discoveryProperties.namingServiceInstance()					.selectInstances(serviceId, group, true);			return instancesToServerList(instances);		}		catch (Exception e) {			throw new IllegalStateException(					"Can not get service instances from nacos, serviceId=" + serviceId,					e);		}	}1
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追踪到yaml配置文件中了：

至此，nacos自己的实现类和nacos软件建立通讯，对list列表进行更新。

6.总结