apollo-common/src/main/java/com/ctrip/framework/apollo/common/datasource/TitanSettings.java/TitanSettings/getTitanUrl
class TitanSettings:  public String getTitanUrl() {
    Env env = EnvUtils.transformEnv(Foundation.server().getEnvType());
    switch (env) {
      case FAT:
      case FWS:
        return fatTitanUrl;
      case UAT:
        return uatTitanUrl;
      case TOOLS:
      case PRO:
        return proTitanUrl;
      default:
        return "";
    }
  }