class AbstractInterfaceConfig extends AbstractMethodConfig {

    protected List<URL> loadRegistries(boolean provider) {
        // 检测是否存在注册中心配置类，不存在则抛出异常
        checkRegistry();
        List<URL> registryList = new ArrayList<URL>();
        if (registries != null && !registries.isEmpty()) {
            for (RegistryConfig config : registries) {
                String address = config.getAddress();
                if (address == null || address.length() == 0) {
                    // 若 address 为空，则将其设为 0.0.0.0
                    address = Constants.ANYHOST_VALUE;
                }
                // 从系统属性中加载注册中心地址
                String sysaddress = System.getProperty("dubbo.registry.address");
                if (sysaddress != null && sysaddress.length() > 0) {
                    address = sysaddress;
                }
                // 检测 address 是否合法
                if (address.length() > 0 && !RegistryConfig.NO_AVAILABLE.equalsIgnoreCase(address)) {
                    Map<String, String> map = new HashMap<String, String>();
                    // 添加 ApplicationConfig 中的字段信息到 map 中
                    appendParameters(map, application);
                    // 添加 RegistryConfig 字段信息到 map 中
                    appendParameters(map, config);
                    // 添加 path、pid，protocol 等信息到 map 中
                    map.put("path", RegistryService.class.getName());
                    map.put("dubbo", Version.getProtocolVersion());
                    map.put(Constants.TIMESTAMP_KEY, String.valueOf(System.currentTimeMillis()));
                    if (ConfigUtils.getPid() > 0) {
                        map.put(Constants.PID_KEY, String.valueOf(ConfigUtils.getPid()));
                    }
                    if (!map.containsKey("protocol")) {
                        if (ExtensionLoader.getExtensionLoader(RegistryFactory.class).hasExtension("remote")) {
                            map.put("protocol", "remote");
                        } else {
                            map.put("protocol", "dubbo");
                        }
                    }
                    List<URL> urls = UrlUtils.parseURLs(address, map);
                    for (URL url : urls) {
                        url = url.addParameter(Constants.REGISTRY_KEY, url.getProtocol());
                        url = url.setProtocol(Constants.REGISTRY_PROTOCOL);
                        if ((provider && url.getParameter(Constants.REGISTER_KEY, true))
                                || (!provider && url.getParameter(Constants.SUBSCRIBE_KEY, true))) {
                            registryList.add(url);
                        }
                    }
                }
            }
        }
        return registryList;
    }

}