这是一个网上的代码，无需数据库，将要缩短的网址存在于一个同目录里的txt文件里。
演示：http://www.ucmbaa.org/u/
目的一是缩短了网址，二是不让搜索引擎识别这个地址。
<body>
<?php
/*
location of file to store URLS
*/
$file = 'urls.txt';
/*
use mod_rewrite: 0 - no or 1 - yes
*/
$use_rewrite = 1;
/*
language/style/output variables
*/
$l_url = 'URL';
$l_nourl = '<strong>没有输入URL地址</strong>';
$l_yoururl = '<strong>你的短网址:</strong>';
$l_invalidurl = '<strong>无效的URL.</strong>';
$l_createurl = '生成短网址';
//////////////////// NO NEED TO EDIT BELOW ////////////////////
if(!is_writable($file) || !is_readable($file))
{
die('Cannot write or read from file. Please CHMOD the url file (urls.txt) by default to 777 and make sure it is uploaded.');
}
$action = trim($_GET['id']);
$action = (empty($action) || $action == '') ? 'create' : 'redirect';
$valid = "^(https?|ftp)\:\/\/([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?[a-z0-9+\$_-]+(\.[a-z0-9+\$_-]+)*(\:[0-9]{2,5})?(\/([a-z0-9+\$_-]\.?)+)*\/?(\?[a-z+&\$_.-][a-z0-9;:@/&%=+\$_.-]*)?(#[a-z_.-][a-z0-9+\$_.-]*)?\$";
$output = '';
if($action == 'create')
{
if(isset($_POST['create']))
{
$url = trim($_POST['url']);
if($url == '')
{
$output = $l_nourl;
}
else
{
if(eregi($valid, $url))
{
$fp = fopen($file, 'a');
fwrite($fp, "{$url}\r\n");
fclose($fp);
$id = count(file($file));
$dir = dirname($_SERVER['PHP_SELF']);
$filename = explode('/', $_SERVER['PHP_SELF']);
$filename = $filename[(count($filename) - 1)];
$shorturl = ($use_rewrite == 1) ? "http://{$_SERVER['HTTP_HOST']}{$dir}{$id}" : "http://{$_SERVER['HTTP_HOST']}{$dir}{$filename}?id={$id}";
$output = "{$l_yoururl} <a href='{$shorturl}' target='_blank'>{$shorturl}</a>";
}
else
{
$output = $l_invalidurl;
}
}
}
}
if($action == 'redirect')
{
$urls = file($file);
$id = trim($_GET['id']) - 1;
if(isset($urls[$id]))
{
header("Location: {$urls[$id]}");
exit;
}
else
{
die('Script error');
}
}
//////////////////// FEEL FREE TO EDIT BELOW ////////////////////
?>
<p>短网址服务可以帮助你把一个长网址缩短，方便你在社交网络和微博上分享链接。</p>
<!-- start html output -->
<form action="<?=$_SERVER['PHP_SELF']?>" method="post">
<p class="response"><?=$output?></p>
<p>
<label for="s-url">请输入URL地址:</label>
<input name="url" type="text" id="s-url" size="60" />
</p>
<p>
<input type="submit" class="button" name="create" value="<?=$l_createurl?>" />
</p>
</form>
<!-- end html output -->
</body>
</html>
<?php
ob_end_flush();
?>