/**
* 当前模型对应表名
*/
public static function getTableName()
{
$classname = get_called_class();
$classname = substr($classname, 0, strlen($classname) - 5);
$classname = preg_replace("/[A-Z]/", "_\\0", $classname);
$classname = trim($classname, '_');
$classname = strtolower($classname);
self::$tablename = $classname;
return $classname;
}