《从面试题看源码》-Dubbo是怎么一个流程将服务注册到注册中心的呢？

@Override
    public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
        // 暴露服务
        // export invoker
        final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker);
        // 获得注册中心 URL
        URL registryUrl = getRegistryUrl(originInvoker);
        // 获得注册中心对象
        // registry provider
        final Registry registry = getRegistry(originInvoker);
        // 获得服务提供者 URL
        final URL registedProviderUrl = getRegistedProviderUrl(originInvoker);
        //to judge to delay publish whether or not
        boolean register = registedProviderUrl.getParameter("register", true);
        // 向注册中心订阅服务消费者
        ProviderConsumerRegTable.registerProvider(originInvoker, registryUrl, registedProviderUrl);
        // 向注册中心注册服务提供者（自己）
        if (register) {
            register(registryUrl, registedProviderUrl);
            ProviderConsumerRegTable.getProviderWrapper(originInvoker).setReg(true); // // 标记向本地注册表的注册服务提供者，已经注册
        }
        // 使用 OverrideListener 对象，订阅配置规则
        // Subscribe the override data
        // FIXME When the provider subscribes, it will affect the scene : a certain JVM exposes the service and call the same service. Because the subscribed is cached key with the name of the service, it causes the subscription information to cover.
        // 创建订阅配置规则的 URL
        final URL overrideSubscribeUrl = getSubscribedOverrideUrl(registedProviderUrl);
        // 创建 OverrideListener 对象，并添加到 `overrideListeners` 中
        final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);
        overrideListeners.put(overrideSubscribeUrl, overrideSubscribeListener);
        // 向注册中心，发起订阅
        registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
        //Ensure that a new exporter instance is returned every time export
        return new DestroyableExporter<T>(exporter, originInvoker, overrideSubscribeUrl, registedProviderUrl);
    }

protected void doRegister(URL url) {
        try {
            zkClient.create(toUrlPath(url), url.getParameter(Constants.DYNAMIC_KEY, true));
        } catch (Throwable e) {
            throw new RpcException("Failed to register " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
        }
    }