网址缩短 短网址程序

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。

3. /*
4. location of file to store URLS
5. */
6. $file = 'urls.txt';
8. /*
9. use mod_rewrite: 0 - no or 1 - yes
10. */
11. $use_rewrite = 1;
13. /*
14. language/style/output variables
15. */
17. $l_url = 'URL';
18. $l_nourl = '没有输入URL地址';
19. $l_yoururl = '你的短网址:';
20. $l_invalidurl = '无效的URL.';
21. $l_createurl = '生成短网址';
23. //////////////////// NO NEED TO EDIT BELOW ////////////////////
25. if(!is_writable($file) || !is_readable($file))
26. {
27. die('Cannot write or read from file. Please CHMOD the url file (urls.txt) by default to 777 and make sure it is uploaded.');
28. }
30. $action = trim($_GET['id']);
31. $action = (empty($action) || $action == '') ? 'create' : 'redirect';
33. $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+\$_.-]*)?\$";
35. $output = '';
37. if($action == 'create')
38. {
39. if(isset($_POST['create']))
40. {
41. $url = trim($_POST['url']);
43. if($url == '')
44. {
45. $output = $l_nourl;
46. }
47. else
48. {
49. if(eregi($valid, $url))
50. {
51. $fp = fopen($file, 'a');
52. fwrite($fp, "{$url}\r\n");
53. fclose($fp);
55. $id = count(file($file));
56. $dir = dirname($_SERVER['PHP_SELF']);
57. $filename = explode('/', $_SERVER['PHP_SELF']);
58. $filename = $filename[(count($filename) - 1)];
60. $shorturl = ($use_rewrite == 1) ? "http://{$_SERVER['HTTP_HOST']}{$dir}{$id}" : "http://{$_SERVER['HTTP_HOST']}{$dir}{$filename}?id={$id}";
62. $output = "{$l_yoururl} {$shorturl}";
63. }
64. else
65. {
66. $output = $l_invalidurl;
67. }
68. }
69. }
70. }
72. if($action == 'redirect')
73. {
74. $urls = file($file);
75. $id = trim($_GET['id']) - 1;
76. if(isset($urls[$id]))
77. {
78. header("Location: {$urls[$id]}");
79. exit;
80. }
81. else
82. {
83. die('Script error');
84. }
85. }
87. //////////////////// FEEL FREE TO EDIT BELOW ////////////////////
88. ?>

91. 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。

93. =$output?>

    请输入URL地址: