PHP生成类似类似优酷、腾讯视频等其他视频链的ID

不知道你注意了没有，类似优酷、腾讯视频等其他视频链接似乎类似这样的

http://v.youku.com/v_show/id_XNjA5MjE5OTM2.html

注意id_xxx那段，是不是看不懂了，但你无可否认这个就是id，这不国外的一位牛人早在09年就写了针对PHP/Python/Javascript/Java/SQL的生成方法，可见我现在是多么的落伍，下面我把代码贴出来，希望分享精神永存。

PHP代码（Get from GitHub）

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<?php /**   * Translates a number to a short alhanumeric version   *   * Translated any number up to 9007199254740992   * to a shorter version in letters e.g.:   * 9007199254740989 --> PpQXn7COf  *  * specifiying the second argument true, it will  * translate back e.g.:  * PpQXn7COf --> 9007199254740989  *  * this function is based on any2dec && dec2any by  * fragmer[at]mail[dot]ru  * see: http://nl3.php.net/manual/en/function.base-convert.php#52450  *  * If you want the alphaID to be at least 3 letter long, use the  * $pad_up = 3 argument  *  * In most cases this is better than totally random ID generators  * because this can easily avoid duplicate ID's.  * For example if you correlate the alpha ID to an auto incrementing ID  * in your database, you're done.  *  * The reverse is done because it makes it slightly more cryptic,  * but it also makes it easier to spread lots of IDs in different  * directories on your filesystem. Example:  * $part1 = substr($alpha_id,0,1);  * $part2 = substr($alpha_id,1,1);  * $part3 = substr($alpha_id,2,strlen($alpha_id));  * $destindir = "/".$part1."/".$part2."/".$part3;  * // by reversing, directories are more evenly spread out. The  * // first 26 directories already occupy 26 main levels  *  * more info on limitation:  * - http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/165372  *  * if you really need this for bigger numbers you probably have to look  * at things like: http://theserverpages.com/php/manual/en/ref.bc.php  * or: http://theserverpages.com/php/manual/en/ref.gmp.php  * but I haven't really dugg into this. If you have more info on those  * matters feel free to leave a comment.  *  * The following code block can be utilized by PEAR's Testing_DocTest  * <code>  * // Input //  * $number_in = 2188847690240;  * $alpha_in  = "SpQXn7Cb";  *  * // Execute //  * $alpha_out  = alphaID($number_in, false, 8);  * $number_out = alphaID($alpha_in, true, 8);  *  * if ($number_in != $number_out) {  *    echo "Conversion failure, ".$alpha_in." returns ".$number_out." instead of the ";  *    echo "desired: ".$number_in."\n";  * }  * if ($alpha_in != $alpha_out) {  *    echo "Conversion failure, ".$number_in." returns ".$alpha_out." instead of the ";  *    echo "desired: ".$alpha_in."\n";  * }  *  * // Show //  * echo $number_out." => ".$alpha_out."\n";  * echo $alpha_in." => ".$number_out."\n";  * echo alphaID(238328, false)." => ".alphaID(alphaID(238328, false), true)."\n";  *  * // expects:  * // 2188847690240 => SpQXn7Cb  * // SpQXn7Cb => 2188847690240  * // aaab => 238328  *  * </code>  *  * @author   Kevin van Zonneveld <kevin@vanzonneveld.net>  * @author   Simon Franz  * @author   Deadfish  * @copyright 2008 Kevin van Zonneveld (http://kevin.vanzonneveld.net)  * @license   http://www.opensource.org/licenses/bsd-license.php New BSD Licence  * @version   SVN: Release: $Id: alphaID.inc.php 344 2009-06-10 17:43:59Z kevin $  * @link   http://kevin.vanzonneveld.net/  *  * @param mixed   $in      String or long input to translate  * @param boolean $to_num  Reverses translation when true  * @param mixed   $pad_up  Number or boolean padds the result up to a specified length  * @param string  $passKey Supplying a password makes it harder to calculate the original ID  *  * @return mixed string or long  */ function alphaID($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, $n ,1);       }         array_multisort($p,  SORT_DESC, $i);       $index = implode($i);   }     $base  = strlen($index);     if ($to_num) {       // Digital number  < 0) {               $out -= pow($base, $pad_up);           }       }       $out = sprintf('%F', $out);       $out = substr($out, 0, 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; }

使用举例

1 2	<?php alphaID(9007199254740989);

执行结果将被返回“fE2XnNGpF”，我们可以把它认为是加密，进行反解密则

1 2	<?php alphaID('fE2XnNGpF', true);

那么就转换成真实的数字“9007199254740989”。方法还可以支持使用key进行加密，使得别人无法解得你真实的ID。