php创造短ID Create short IDs with PHP - Like Youtube or TinyURL
?
?
More is Less - the 'math'
The alphabet has 26 characters. That's a lot more than 10 digits. If we also distinguish upper- and lowercase, and add digits to the bunch or the heck of it, we already have (26 x 2 + 10)?62 options?we can use?per position?in the ID.
Now of course we can also add additional funny characters to 'the bunch' like - / * & # but those may cause problems in URLs and that's our target audience for now.
OK so because there are roughly?6x more characters?we will use per position, IDs will get much?shorter. We can just fit a lot?more data in each position.
This is basically what url shortening services do like tinyurl, is.gd, or bit.ly. But similar IDs can also be found at youtube:?http://www.youtube.com/watch?v=yzNjIBEdyww
Convert your IDs
Now unlike Database servers: webservers are easy to scale so you can let them do a bit of converting to ease the life of your users, while keeping your database fast with numbers (MySQL really likes them plain numbers ; ).
To do the conversion I've written a PHP function that can translate big numbers to short strings and vice versa. I call it: alphaID.
The resulting string is not hard to decipher, but it can be a very nice feature to make URLs or directorie structures more compact and significant.
So basically:
- when someone requests rLHWfKd
- alphaID() converts it to 999999999999
- you lookup the record for id 999999999999 in your database
?
?
Source
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 ** // 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 * ** * @author Kevin van Zonneveld * @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; $n0) $out -= pow($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;}
?
Example
Running:
alphaID(9007199254740989);
will return 'PpQXn7COf' and:
alphaID('PpQXn7COf', true);
will return '9007199254740989'
Easy right?
More features
- There also is an optional third argument:?
$pad_up. This enables you to make the resulting alphaId at least?X?characters long. - You can support even more characters (making the resulting alphaID even smaller) by adding characters to the?
$index?var at the top of the function body.
?
?
?
JavaScript Implementation
Thanks to Even Simon, there's a JavaScript implementation. You will also find PHP version there, that implements the encode & decode functions as separate methods in a class.
?
?
Python Implementation
Thanks to?wessite, there's a Python implementation.
?
ALPHABET = "bcdfghjklmnpqrstvwxyz0123456789BCDFGHJKLMNPQRSTVWXYZ"BASE = len(ALPHABET)MAXLEN = 6 def encode_id(self, n): pad = self.MAXLEN - 1 n = int(n + pow(self.BASE, pad)) s = [] t = int(math.log(n, self.BASE)) while True: bcp = int(pow(self.BASE, t)) a = int(n / bcp) % self.BASE s.append(self.ALPHABET[a:a+1]) n = n - (a * bcp) t -= 1 if t l: break pad = self.MAXLEN - 1 s = int(s - pow(self.BASE, pad)) return int(s)
?
Python Implementation
Thanks to?Andy Li, there's a HaXe implementation.
?/** * HaXe version of AlphabeticID * Author: Andy Li * ported from... * * Javascript AlphabeticID class * Author: Even Simon * which is based on a script by Kevin van Zonneveld ) * * Description: Translates a numeric identifier into a short string and backwords. * http://kevin.vanzonneveld.net/techblog/article/create_short_ids_with_php_like_youtube_or_tinyurl/ **/ class AlphaID { static public var index:String = 'abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'; static public function encode(_number:Int):String { var strBuf = new StringBuf(); var i = 0; var end = Math.floor(Math.log(_number)/Math.log(index.length)); while(i ?
?来源：http://kevin.vanzonneveld.net/techblog/article/create_short_ids_with_php_like_youtube_or_tinyurl/
?
?
声明：本文内容由网友自发贡献，版权归原作者所有，本站不承担相应法律责任。如您发现有涉嫌抄袭侵权的内容，请联系admin@php.cn核实处理。
相关文章
相关视频