php強制使用者轉向www網域名稱的方法_php技巧

本文執行個體講述了php強制使用者轉向www網域名稱的方法。分享給大家供大家參考。具體分析如下：

有時候網站的www網域名稱和非www網域名稱都能訪問網站，但是這樣不利於搜尋引擎的收錄，會分散網頁的權重，所以希望使用者訪問非www的網域名稱時通過301永久重新導向到www網域名稱，例如使用者訪問jb51.net會直接轉向www.jb51.net，本php代碼考慮了無法通過head重新導向的情況，會在頁面上輸出連結，讓使用者點擊。

// 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.jb51.net" but some other // applications send host names like "www.jb51.net: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.jb51.net'){  // 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.jb51.net' . $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.jb51.net' . $url.'">Please click here</a>';  // stop the script execution here  exit;}// If the domain is www.jb51.net then go on with your PHP code // of with your website...// BTW: You need to replace jb51.net trough your own domain :-D

希望本文所述對大家的php程式設計有所協助。