Nacos – 启动提到了NacosWatch#start会获取NamingService，他托管NacosServiceManager来完成这件事。

NacosServiceManager#getNamingService

为空的时候，去创建一个NamingService

public NamingService getNamingService(Properties properties) {

// 为空的时候，去创建一个NamingService

if (Objects.isNull(this.namingService)) {

buildNamingService(properties);

}

// 返回namingService

return namingService;

}

NacosServiceManager#buildNamingService

加锁保证只能有一个namingService

private NamingService buildNamingService(Properties properties) {

if (Objects.isNull(namingService)) {

// 加锁保证只能有一个namingService

synchronized (NacosServiceManager.class) {

if (Objects.isNull(namingService)) {

namingService = createNewNamingService(properties);

}

}

}

return namingService;

}

最终调用NamingFactory#createNamingService来创建NamingService对象。

private NamingService createNewNamingService(Properties properties) {

try {

return createNamingService(properties);

}

catch (NacosException e) {

throw new RuntimeException(e);

}

}

// NacosFactory中的方法

public static NamingService createNamingService(Properties properties) throws NacosException {

return NamingFactory.createNamingService(properties);

}

NamingFactory#createNamingService

通过反射的方式创建了com.alibaba.nacos.client.naming.NacosNamingService对象。

public static NamingService createNamingService(String serverList) throws NacosException {

try {

Class> driverImplClass = Class.forName("com.alibaba.nacos.client.naming.NacosNamingService");

Constructor constructor = driverImplClass.getConstructor(String.class);

NamingService vendorImpl = (NamingService) constructor.newInstance(serverList);

return vendorImpl;

} catch (Throwable e) {

throw new NacosException(NacosException.CLIENT_INVALID_PARAM, e);

}

}

NacosNamingService#init

主要是初始化namespace、序列化、注册中心服务地址、WebRootContext上下文、缓存路径、日志名称、EventDispatcher、NamingProxy、BeatReactor、HostReactor。

EventDispatcher负责处理服务监听相关。

NamingProxy负责和Nacos服务的通信，比如服务注册、服务取消注册、心跳等。

BeatReactor负责检测心跳。

HostReactor负责获取、更新并保存服务信息。

private void init(Properties properties) throws NacosException {

ValidatorUtils.checkInitParam(properties);

// namespace默认public

this.namespace = InitUtils.initNamespaceForNaming(properties);

// 序列化初始化

InitUtils.initSerialization();

// 注册中心服务地址初始化，这个从配置文件取

initServerAddr(properties);

//初始化WebRootContext上下文

InitUtils.initWebRootContext();

// 初始化缓存路径 System.getProperty("user.home") + "/nacos/naming/" + namespace

initCacheDir();

// 初始化日志名称naming.log

initLogName(properties);

// 初始化EventDispatcher

this.eventDispatcher = new EventDispatcher();

// 初始化NamingProxy

this.serverProxy = new NamingProxy(this.namespace, this.endpoint, this.serverList, properties);

// 初始化BeatReactor

this.beatReactor = new BeatReactor(this.serverProxy, initClientBeatThreadCount(properties));

// 初始化HostReactor

this.hostReactor = new HostReactor(this.eventDispatcher, this.serverProxy, beatReactor, this.cacheDir,

isLoadCacheAtStart(properties), initPollingThreadCount(properties));

}