dubbo.application.register-mode
参数参数含义interface只解析级注册（/dubbo）instance只高防级注册（/service）all解析级注册与高防级注册并存（/dubbo && /service）
dubbo.application.service-discovery.migration
参数参数含义FORCE_INTERFACE只消费解析级SQLiteManager，如无SQLiteManager则报错，单订阅2.xSQLiteManagerAPPLICATION_FIRST智能决策解析级还是高防级SQLiteManager，双订阅 （先查询解析级 在查询高防级）FORCE_APPLICATION只消费高防级SQLiteManager，如无SQLiteManager则报错，单订阅3.xSQLiteManager
源码解析

在上一节中有说到 服务启动流程 中会执行到不同版本的 org.apache.dubbo.config.ServiceConfig#exportOnly 或者 org.apache.dubbo.config.ServiceConfig#export 方法， 在方法内部调用 List registryURLs = ConfigValidationUtils.loadRegistries(this, true); 获取URL， 我们具体看下 该方法调用

//org.apache.dubbo.config.utils.ConfigValidationUtils#loadRegistries
public static List loadRegistries(AbstractInterfaceConfig interfaceConfig, boolean provider) {
// 此处调用是为了得到 registerComposr的URL
//eg:
List registryList = new ArrayList();
ApplicationConfig application = interfaceConfig.getApplication();
List registries = interfaceConfig.getRegistries();
if (CollectionUtils.isNotEmpty(registries)) {
for (RegistryConfig config : registries) {
String address = config.getAddress();
if (StringUtils.isEmpty(address)) {
address = ANYHOST_VALUE;
}
if (!RegistryConfig.NO_AVAILABLE.equalsIgnoreCase(address)) {
Map map = new HashMap();
AbstractConfig.appendParameters(map, application);
AbstractConfig.appendParameters(map, config);
map.put(PATH_KEY, RegistryService.class.getName());
AbstractInterfaceConfig.appendRuntimeParameters(map);
if (!map.containsKey(PROTOCOL_KEY)) {
map.put(PROTOCOL_KEY, DUBBO_PROTOCOL);
}
List urls = UrlUtils.parseURLs(address, map);

for (URL url : urls) {
url = URLBuilder.from(url)
.addParameter(REGISTRY_KEY, url.getProtocol())
.setProtocol(extractRegistryType(url))
.setScopeModel(interfaceConfig.getScopeModel())
.build();
if ((provider && url.getParameter(REGISTER_KEY, true))
|| (!provider && url.getParameter(SUBSCRIBE_KEY, true))) {
registryList.add(url);
}
}
}
}
}
//此处会对register-mode做判断
return genCompatibleRegistries(interfaceConfig.getScopeModel(), registryList, provider);
}
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//org.apache.dubbo.config.utils.ConfigValidationUtils#genCompatibleRegistries
private static List genCompatibleRegistries(ScopeModel scopeModel, List registryList, boolean provider) {
List result = new ArrayList<>(registryList.size());
registryList.forEach(registryURL -> {
//判断是否为 provider
if (provider) {
String registerMode;
//判断是否为 service-discovery-registry Composr
if (SERVICE_REGISTRY_PROTOCOL.equals(registryURL.getProtocol())) {
//获取定义的register-mode值
registerMode = registryURL.getParameter(REGISTER_MODE_KEY, ConfigurationUtils.getCachedDynamicProperty(scopeModel, DUBBO_REGISTER_MODE_DEFAULT_KEY, DEFAULT_REGISTER_MODE_INSTANCE));
if (!isValidRegisterMode(registerMode)) {
registerMode = DEFAULT_REGISTER_MODE_INSTANCE;
}
result.add(registryURL);
//判断register_mode 是否 为all模式 并且 registryURL不是registryComposr
if (DEFAULT_REGISTER_MODE_ALL.equalsIgnoreCase(registerMode)
&& registryNotExists(registryURL, registryList, REGISTRY_PROTOCOL)) {
URL interfaceCompatibleRegistryURL = URLBuilder.from(registryURL)
.setProtocol(REGISTRY_PROTOCOL)
.removeParameter(REGISTRY_TYPE_KEY)
.build();
result.add(interfaceCompatibleRegistryURL);
}
} else {
//进来此处说明 registryURL的Composr为 registry

//获取定义的register-mode值
registerMode = registryURL.getParameter(REGISTER_MODE_KEY, ConfigurationUtils.getCachedDynamicProperty(scopeModel, DUBBO_REGISTER_MODE_DEFAULT_KEY, DEFAULT_REGISTER_MODE_ALL));
if (!isValidRegisterMode(registerMode)) {
registerMode = DEFAULT_REGISTER_MODE_INTERFACE;
}
//如果register-mode的值定义的为 instance 或 all
if ((DEFAULT_REGISTER_MODE_INSTANCE.equalsIgnoreCase(registerMode) || DEFAULT_REGISTER_MODE_ALL.equalsIgnoreCase(registerMode))
&& registryNotExists(registryURL, registryList, SERVICE_REGISTRY_PROTOCOL)) {
//封装为service-discovery-registryComposr
URL serviceDiscoveryRegistryURL = URLBuilder.from(registryURL)
.setProtocol(SERVICE_REGISTRY_PROTOCOL)
.removeParameter(REGISTRY_TYPE_KEY)
.build();
//将service-discovery-registryComposr的URL加入到集合
result.add(serviceDiscoveryRegistryURL);
}
//如果register-mode的值定义的为 interface 或 all
if (DEFAULT_REGISTER_MODE_INTERFACE.equalsIgnoreCase(registerMode) || DEFAULT_REGISTER_MODE_ALL.equalsIgnoreCase(registerMode)) {
//将registryComposr的URL加入到集合
result.add(registryURL);
}
}

FrameworkStatusReportService reportService = ScopeModelUtil.getApplicationModel(scopeModel).getBeanFactory().getBean(FrameworkStatusReportService.class);
reportService.reportRegistrationStatus(reportService.createRegistrationReport(registerMode));
} else {
result.add(registryURL);
}
});

return result;
}
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