private void doExportUrls() {List<URL> registryURLs = loadRegistries(true);    // 获取注册中心的配置for (ProtocolConfig protocolConfig : protocols) {  //获取配置的服务暴露协义doExportUrlsFor1Protocol(protocolConfig, registryURLs);  //真正的暴露，通过协义和注册中心去完成暴露}}

　　　　 String name = protocolConfig.getName();if (name == null || name.length() == 0) {name = "dubbo";}String host = protocolConfig.getHost();if (provider != null && (host == null || host.length() == 0)) {host = provider.getHost();}boolean anyhost = false;if (NetUtils.isInvalidLocalHost(host)) {anyhost = true;try {host = InetAddress.getLocalHost().getHostAddress();} catch (UnknownHostException e) {logger.warn(e.getMessage(), e);}if (NetUtils.isInvalidLocalHost(host)) {if (registryURLs != null && registryURLs.size() > 0) {for (URL registryURL : registryURLs) {try {Socket socket = new Socket();try {SocketAddress addr = new InetSocketAddress(registryURL.getHost(), registryURL.getPort());socket.connect(addr, 1000);host = socket.getLocalAddress().getHostAddress();break;} finally {try {socket.close();} catch (Throwable e) {}}} catch (Exception e) {logger.warn(e.getMessage(), e);}}}if (NetUtils.isInvalidLocalHost(host)) {host = NetUtils.getLocalHost();}}}

 　　　　Integer port = protocolConfig.getPort();if (provider != null && (port == null || port == 0)) {port = provider.getPort();}final int defaultPort = ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(name).getDefaultPort();if (port == null || port == 0) {port = defaultPort;}if (port == null || port <= 0) {port = getRandomPort(name);if (port == null || port < 0) {port = NetUtils.getAvailablePort(defaultPort);putRandomPort(name, port);}logger.warn("Use random available port(" + port + ") for protocol " + name);}

Map<String, String> map = new HashMap<String, String>();if (anyhost) {map.put(Constants.ANYHOST_KEY, "true");}map.put(Constants.SIDE_KEY, Constants.PROVIDER_SIDE);map.put(Constants.DUBBO_VERSION_KEY, Version.getVersion());map.put(Constants.TIMESTAMP_KEY, String.valueOf(System.currentTimeMillis()));if (ConfigUtils.getPid() > 0) {map.put(Constants.PID_KEY, String.valueOf(ConfigUtils.getPid()));}appendParameters(map, application);appendParameters(map, module);appendParameters(map, provider, Constants.DEFAULT_KEY);appendParameters(map, protocolConfig);appendParameters(map, this);if (methods != null && methods.size() > 0) {  //服务接口的方法for (MethodConfig method : methods) {appendParameters(map, method, method.getName());String retryKey = method.getName() + ".retry";if (map.containsKey(retryKey)) {String retryValue = map.remove(retryKey);if ("false".equals(retryValue)) {map.put(method.getName() + ".retries", "0");}}List<ArgumentConfig> arguments = method.getArguments();　　　　　　　　　//处理方法的参数，并看是否有回调参数if (arguments != null && arguments.size() > 0) {  for (ArgumentConfig argument : arguments) {//类型自动转换.if(argument.getType() != null && argument.getType().length() >0){Method[] methods = interfaceClass.getMethods();//遍历所有方法if(methods != null && methods.length > 0){for (int i = 0; i < methods.length; i++) {String methodName = methods[i].getName();//匹配方法名称，获取方法签名.if(methodName.equals(method.getName())){Class<?>[] argtypes = methods[i].getParameterTypes();//一个方法中单个callbackif (argument.getIndex() != -1 ){if (argtypes[argument.getIndex()].getName().equals(argument.getType())){appendParameters(map, argument, method.getName() + "." + argument.getIndex());}else {throw new IllegalArgumentException("argument config error : the index attribute and type attirbute not match :index :"+argument.getIndex() + ", type:" + argument.getType());}} else {//一个方法中多个callbackfor (int j = 0 ;j<argtypes.length ;j++) {Class<?> argclazz = argtypes[j];if (argclazz.getName().equals(argument.getType())){appendParameters(map, argument, method.getName() + "." + j);if (argument.getIndex() != -1 && argument.getIndex() != j){throw new IllegalArgumentException("argument config error : the index attribute and type attirbute not match :index :"+argument.getIndex() + ", type:" + argument.getType());}}}}}}}}else if(argument.getIndex() != -1){appendParameters(map, argument, method.getName() + "." + argument.getIndex());}else {throw new IllegalArgumentException("argument config must set index or type attribute.eg: <dubbo:argument index='0' .../> or <dubbo:argument type=xxx .../>");}}}} // end of methods for
        }if (ProtocolUtils.isGeneric(generic)) { //泛化方式map.put("generic", generic);map.put("methods", Constants.ANY_VALUE);} else {String revision = Version.getVersion(interfaceClass, version);if (revision != null && revision.length() > 0) {map.put("revision", revision);}String[] methods = Wrapper.getWrapper(interfaceClass).getMethodNames(); //获取包装类,包装类实质上就是通过javassist生成的类，当我们通过包装类对角调dubbo接口时实际调的还是接口对象的原有方法。此处包装起到的作用无非是可以以统一的代码的去调用用户提供的不同的dubbo接口if(methods.length == 0) {logger.warn("NO method found in service interface " + interfaceClass.getName());map.put("methods", Constants.ANY_VALUE);}else {map.put("methods", StringUtils.join(new HashSet<String>(Arrays.asList(methods)), ","));}}if (! ConfigUtils.isEmpty(token)) {if (ConfigUtils.isDefault(token)) {map.put("token", UUID.randomUUID().toString());} else {map.put("token", token);}}if ("injvm".equals(protocolConfig.getName())) {protocolConfig.setRegister(false);map.put("notify", "false");}

// 导出服务String contextPath = protocolConfig.getContextpath();  //获取协议的上下文路径if ((contextPath == null || contextPath.length() == 0) && provider != null) {contextPath = provider.getContextpath();}//拼接urlURL url = new URL(name, host, port, (contextPath == null || contextPath.length() == 0 ? "" : contextPath + "/") + path, map);//这里的ConfiguratorFactory是个扩展，可以用来设计自己的URL组成规则if (ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class).hasExtension(url.getProtocol())) {url = ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class).getExtension(url.getProtocol()).getConfigurator(url).configure(url);}

String scope = url.getParameter(Constants.SCOPE_KEY);//配置为none不暴露if (! Constants.SCOPE_NONE.toString().equalsIgnoreCase(scope)) {//配置不是remote的情况下做本地暴露 (配置为remote，则表示只暴露远程服务)if (!Constants.SCOPE_REMOTE.toString().equalsIgnoreCase(scope)) {exportLocal(url);}//如果配置不是local则暴露为远程服务.(配置为local，则表示只暴露远程服务)if (! Constants.SCOPE_LOCAL.toString().equalsIgnoreCase(scope) ){if (logger.isInfoEnabled()) {logger.info("Export dubbo service " + interfaceClass.getName() + " to url " + url);} //只有远程暴露才需要用到注册中心urlif (registryURLs != null && registryURLs.size() > 0&& url.getParameter("register", true)) {for (URL registryURL : registryURLs) {url = url.addParameterIfAbsent("dynamic", registryURL.getParameter("dynamic"));//获取监控中心的URL，此处先暂不关心生成的细节，待到服务治理时才详细分析URL monitorUrl = loadMonitor(registryURL);if (monitorUrl != null) {url = url.addParameterAndEncoded(Constants.MONITOR_KEY, monitorUrl.toFullString());}if (logger.isInfoEnabled()) {logger.info("Register dubbo service " + interfaceClass.getName() + " url " + url + " to registry " + registryURL);}//这里对参数做个介绍：                          参数1：ref就是接口实现类                             参数2：interfaceClass:接口类                             参数3：在registryURL上添加参数，key为"export",value就是前面产生的服务协义的url                        //proxyFactory的来历                          ExtensionLoader.getExtensionLoader(ProxyFactory.class).getAdaptiveExtension()                          这个类实例最终就是com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory类的实例，这是由于ProxyFactory类上                           的注解决定的Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString()));Exporter<?> exporter = protocol.export(invoker);exporters.add(exporter);}} else {  //这个是用来没有注册中心情况下的暴露，应该是用于直连的场景Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);Exporter<?> exporter = protocol.export(invoker);exporters.add(exporter);}}}this.urls.add(url);