Dubbo-服务提供者初始化

protected synchronized void doExport() {
    // 
    checkApplication();
    checkRegistry();
    checkProtocol();
    appendProperties(this);
    checkStubAndMock(interfaceClass);
    if (path == null || path.length() == 0) {
        path = interfaceName;
    }
    doExportUrls();
}

private void doExportUrls() {
    List<URL> registryURLs = loadRegistries(true);
    for (ProtocolConfig protocolConfig : protocols) {
        doExportUrlsFor1Protocol(protocolConfig, registryURLs);
    }
}

private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {
    
    //如果不是remote，则暴露本地服务
    if (!Constants.SCOPE_REMOTE.toString().equalsIgnoreCase(scope)) {
        exportLocal(url);
    }    
    // 如果配置不是local则暴露为远程服务
    if (!Constants.SCOPE_LOCAL.toString().equalsIgnoreCase(scope)) {
        // 如果注册中心地址不为null
        if (registryURLs != null && registryURLs.size() > 0) {
            for (URL registryURL : registryURLs) {
                url = url.addParameterIfAbsent("dynamic", registryURL.getParameter("dynamic"));
                // 忽略不相干的代码 ...
                // 通过代理工厂将ref对象转化成invoker对象
                Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString()));
                // 代理invoker对象
                DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);
                // 暴露服务
                Exporter<?> exporter = protocol.export(wrapperInvoker);
                // 一个服务可能有多个提供者，保存在一起
                exporters.add(exporter);
            }
        } else {
            Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);
            DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);

            Exporter<?> exporter = protocol.export(wrapperInvoker);
            exporters.add(exporter);
        }
    }
}

public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
    URL url = invoker.getUrl();
    //忽略若干代码
    //打开服务
    openServer(url);
    optimizeSerialization(url);
    return exporter;
}

private void openServer(URL url) {

    String key = url.getAddress();
    boolean isServer = url.getParameter(Constants.IS_SERVER_KEY, true);
    //是否server端
    if (isServer) {
        ExchangeServer server = serverMap.get(key);
        if (server == null) {
            //如果服务不存在，创建服务
            serverMap.put(key, createServer(url));
        } else {
            server.reset(url);
        }
    }
}

private ExchangeServer createServer(URL url) {
    //忽略若干代码
    ExchangeServer server;
    try {
        server = Exchangers.bind(url, requestHandler);
    } catch (RemotingException e) {
        throw new RpcException("Fail to start server(url: " + url + ") " + e.getMessage(), e);
    }
    return server;
}

import com.alibaba.dubbo.common.extension.ExtensionLoader;
public class Protocol$Adpative implements com.alibaba.dubbo.rpc.Protocol {
    public void destroy() {
        // 抛出异常，省略
    }
    public int getDefaultPort() {
        // 抛出异常，省略
    }
    // export
    public com.alibaba.dubbo.rpc.Exporter export(com.alibaba.dubbo.rpc.Invoker arg0) throws RpcException {
        if (arg0 == null) 
            throw new IllegalArgumentException("com.alibaba.dubbo.rpc.Invoker argument == null");
        if (arg0.getUrl() == null) 
            throw new IllegalArgumentException("com.alibaba.dubbo.rpc.Invoker argument getUrl() == null");
        com.alibaba.dubbo.common.URL url = arg0.getUrl();
        String extName = ( url.getProtocol() == null ? "dubbo" : url.getProtocol() );
        if(extName == null) 
            throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url(" 
                                            + url.toString() + ") use keys([protocol])");
        Protocol extension = (Protocol)ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(extName);
        return extension.export(arg0);
    }
    public Invoker refer(java.lang.Class arg0, com.alibaba.dubbo.common.URL arg1) throws RpcException {
        if (arg1 == null) 
            throw new IllegalArgumentException("url == null");
        com.alibaba.dubbo.common.URL url = arg1;
        String extName = ( url.getProtocol() == null ? "dubbo" : url.getProtocol() );
        if(extName == null) 
            throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url(" 
                                            + url.toString() + ") use keys([protocol])");
        Protocol extension = (Protocol)ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(extName);
        return extension.refer(arg0, arg1);
    }
}