微博短链接算法php版本实现代码
思路：
1)将长网址md5生成32位签名串,分为4段,每段8个字节;
2)对这四段循环处理,取8个字节,将他看成16进制串与0x3fffffff(30位1)与操作,即超过30位的忽略处理;
3)这30位分成6段,每5位的数字作为字母表的索引取得特定字符,依次进行获得6位字符串;
4)总的md5串可以获得4个6位串; 取里面的任意一个就可作为这个长url的短URL地址;
下面是PHP代码:
<div class="codetitle"><a style="CURSOR: pointer" data="2038" class="copybut" id="copybut2038" onclick="doCopy('code2038')"> 代码如下:
<div class="codebody" id="code2038">
function shorturl($url='',$prefix='',$suffix='') {
$base = array (
'a','b','c','d','e','f','g','h',
'i','j','k','l','m','n','o','p',
'q','r','s','t','u','v','w','x',
'y','z','0','1','2','3','4','5');
$hex = md5($prefix.$url.$suffix);
$hexLen = strlen($hex);
$subHexLen = $hexLen / 8;
$output = array();
for ($i = 0; $i < $subHexLen; $i++) {
$subHex = substr ($hex,$i
8,8);
$int = 0x3FFFFFFF & (1 ('0x'.$subHex));
$out = '';
for ($j = 0; $j < 6; $j++) {
$val = 0x0000001F & $int;
$out .= $base[$val];
$int = $int >> 5;
}
$output[] = $out;
}
return $output;
}
$urls = shorturl('//www.jb51.cc/');
var_dump($urls);
