/**
+----------------------------------------------------------
* 取得数据库类实例
+----------------------------------------------------------
* @static
* @access public
+----------------------------------------------------------
* @return mixed 返回数据库驱动类
+----------------------------------------------------------
*/
public static function getInstance($db_config = '')
{
if (self::$_instance == null) {
self::$_instance = new Db($db_config);
}
return self::$_instance;
}