PHP随机URL名称(短URL)

怎么运行的：

基本上你有一个字符串是唯一的,但它可以解密代表一个数字,你应该把它看作一个简短的加密/解密.

您有一个函数可以使用唯一的ID,然后从该ID创建一个唯一的“短字符串”,然后可以反转该过程以从短字符串中获取唯一的ID.

这是一个我已经找到一个网站的剪辑：

function alphaID($in,$to_num = false,$pad_up = false,$passKey = null)
{
    $index = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    if ($passKey !== null)
    {
        /* Although this function's purpose is to just make the
        * ID short - and not so much secure,* with this patch by Simon Franz (http://blog.snaky.org/)
        * you can optionally supply a password to make it harder
        * to calculate the corresponding numeric ID */

        for ($n = 0; $n<strlen($index); $n++)
        {
            $i[] = substr( $index,$n,1);
        }

        $passhash = hash('sha256',$passKey);

        $passhash = (strlen($passhash) < strlen($index)) ? hash('sha512',$passKey) : $passhash;

        for ($n=0; $n < strlen($index); $n++)
        {
            $p[] =  substr($passhash,1);
        }

        array_multisort($p,SORT_DESC,$i);
        $index = implode($i);
    }

    $base  = strlen($index);

    if ($to_num)
    {
        // Digital number  <<--  alphabet letter code
        $in  = strrev($in);
        $out = 0;
        $len = strlen($in) - 1;

        for ($t = 0; $t <= $len; $t++)
        {
            $bcpow = bcpow($base,$len - $t);
            $out   = $out + strpos($index,substr($in,$t,1)) * $bcpow;
        }

        if (is_numeric($pad_up))
        {
            $pad_up--;
            if ($pad_up > 0)
            {
                $out -= pow($base,$pad_up);
            }
        }
        $out = sprintf('%F',$out);
        $out = substr($out,strpos($out,'.'));
    }
    else
    {
        // Digital number  -->>  alphabet letter code
        if (is_numeric($pad_up))
        {
            $pad_up--;
            if ($pad_up > 0)
            {
                $in += pow($base,$pad_up);
            }
        }

        $out = "";
        for ($t = floor(log($in,$base)); $t >= 0; $t--)
        {
            $bcp = bcpow($base,$t);
            $a   = floor($in / $bcp) % $base;
            $out = $out . substr($index,$a,1);
            $in  = $in - ($a * $bcp);
        }
        $out = strrev($out); // reverse
    }
    return $out;
}

例

alphaID(9007199254740989);   //-> PpQXn7COf
alphaID('PpQXn7COf',true);  //-> 9007199254740989

这里有一个脚本链接：https://github.com/kvz/deprecated/blob/kvzlib/php/functions/alphaID.inc.php