CodeIgniter框架提示Disallowed Key Characters的解决办法

function _clean_input_keys($str)
    {
        if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str))
        {
            exit('Disallowed Key Characters.');
        }

        // Clean UTF-8 if supported
        if (UTF8_ENABLED === TRUE)
        {
            $str = $this->uni->clean_string($str);
        }

        return $str;
}

class AI_Input extends CI_Input {

    //构造函数
    function __construct(){
        parent::__construct();
    }

    function _clean_input_keys($str)
    {
        if(preg_match("/^,_[a-z0-9:_\/-]+$/",$str)){
            $str = preg_replace("/,_/","",$str);
        }

        if ( ! preg_match("/^[a-z0-9:_\/-]+$/i", $str))
        {
            exit('Disallowed Key Characters.'.$str);
        }
        return $str;
    }
}