php强制用户转向www域名的方法

本文实例讲述了php强制用户转向www域名的方法。分享给大家供大家参考。具体分析如下：

有时候网站的www域名和非www域名都能访问网站，但是这样不利于搜索引擎的收录，会分散网页的权重，所以希望用户访问非www的域名时通过301永久重定向到www域名，例如用户访问zzvips.com会直接转向www.zzvips.com，本php代码考虑了无法通过head重定向的情况，会在页面上输出链接，让用户点击。

									// Install info.:

									// Copy and paste these lines into your default index.php or

									// the file that get's called if a visitor comes on your 

									// website...

									// read the host from the server environment

									$host = $_SERVER["HTTP_HOST"];

									// fix host name - we never now... ;-)

									$host = strtolower($host);

									$host = trim($host);

									// This is important: 

									// Webbrowsers like Firefox are doing their request without

									// the port number like "www.zzvips.com" but some other 

									// applications send host names like "www.zzvips.com:80" 

									$host = str_replace(':80', '', $host);

									$host = trim($host);

									// if the host is not starting with www. redirect the 

									// user to the same URL but with www :-)

									if ($host != 'www.zzvips.com'){

									  // You an also change the "!=" to "==", if you want to force 

									  // the user to use the domain name without the www. 

									  // send status header, so that search engines or other services

									  // detect that this is a permanent redirect and not a temporary

									  header('HTTP/1.1 301 Moved Permanently');

									  // read the URL the user requested:

									  $url = isset($_SERVER["REQUEST_URI"]) ? $_SERVER["REQUEST_URI"] : '';

									  // redirect the user to the new destination:

									  header('Location: http://www.zzvips.com' . $url);

									  // Convert "special" chars -- cause we never now... ;-)

									  $url = htmlspecialchars($url);

									  // "fallback" link, if the browser is not supporting header redirects

									  print '<a href="http://www.zzvips.com' . $url.'">Please click here</a>';

									  // stop the script execution here

									  exit;

									}

									// If the domain is www.zzvips.com then go on with your PHP code 

									// of with your website...

									// BTW: You need to replace zzvips.com trough your own domain :-D

希望本文所述对大家的php程序设计有所帮助。

php强制用户转向www域名的方法

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