PHP 301 url redirect

redirect.php

<?php
// http://wangye.org/blog/archives/4/
// 定义你自己的URL路由表
// 比如下面的路由表将会把
// read.php?paramA=1&paramB=2&paramC=3
// 变成
// /post/1/2/3/
$router = array(
  'read.php'=>'/post/'
);
$server_name = $_SERVER['SERVER_NAME'];
if(!stristr($server_name, 'www.')) {
  $fn = explode('/', strtolower($_SERVER['PHP_SELF']));
  if (array_key_exists($fn[0], $router)) {
    $path = $router[$fn[0]] .
      implode('/',
        array_filter($_REQUEST,
           create_function('$v','return !empty($v);')));
  } else {
    $pathinfo = parse_url($_SERVER['REQUEST_URI']);
    $path = $_SERVER['PHP_SELF']."?".$pathinfo['query'];
  }
  header("HTTP/1.1 301 Moved Permanently");
  header("Location: http://www." . $server_name . $path);
}
?>