php301跳转

<?php$the_host = $_SERVER['HTTP_HOST'];//取得当前域名$the_url = isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : '';//判断地址后面部分$the_url = strtolower($the_url);//将英文字母转成小写if($the_url=="/index.php")//判断是不是首页{    $the_url="";//如果是首页，赋值为空}if($the_host == 'www.baidu.com'){    header('HTTP/1.1 301 Moved Permanently');//发出301头部    header('Location:http://www.taobao.com'.$the_url);//跳转到带www的网址}?>