<VirtualHost *:80>
  ServerAdmin admin@163.com
  DocumentRoot "D:/www/cms"
  ServerName www.mysite.com
  ServerAlias *.mysite.com #这里采用泛解析的方式
  ErrorLog "logs/mysite.com-error.log"
  CustomLog "logs/mysite.com.log" common
</VirtualHost>

127.0.0.1 www.mysite.com
127.0.0.1 category.mysite.com

/**
 * Set the URI String
 *
 * @access public
 * @param string
 * @return string
 */
function _set_uri_string($str)
{
 // Filter out control characters
 $str = remove_invisible_characters($str, FALSE);
 // If the URI contains only a slash we'll kill it
 $this->uri_string = ($str == '/') ? '' : $str;
 // Add by fengyun for url rewrite at 2013-1-25 1:02:27
 @include(APPPATH.'config/domain'.EXT);
 $arrServerName = explode('.', $_SERVER['SERVER_NAME']);
 if (in_array($arrServerName[0], $domain)) {
 $this->uri_string = '/' . $arrServerName[0]."/" . $this->uri_string;
 }
}

<?php
if ( ! defined('BASEPATH'))
exit('No direct script access allowed');
$domain = array('category',"detail","info","archive");