singleton单例模式

class Db {
   static private $_instance;
   static private $_connectSource;
   private $_dbConfig = array(
      'host' => '127.0.0.1',
      'user' => 'root',
      'password' => '',
      'database' => 'video',
   );

   private function __construct() {
   }

   static public function getInstance() {
      if(!(self::$_instance instanceof self)) {
         self::$_instance = new self();
      }
      return self::$_instance;
   }

   public function connect() {
      if(!self::$_connectSource) {
         self::$_connectSource = @mysql_connect($this->_dbConfig['host'], $this->_dbConfig['user'], $this->_dbConfig['password']);  

         if(!self::$_connectSource) {
            throw new Exception('mysql connect error ' . mysql_error());
            //die('mysql connect error' . mysql_error());
}
         
         mysql_select_db($this->_dbConfig['database'], self::$_connectSource);
         mysql_query("set names UTF8", self::$_connectSource);
      }
      return self::$_connectSource;
   }
}
/*$connect = Db::getInstance()->connect();
$sql = "select * from video";
$result = mysql_query($sql, $connect);
echo mysql_num_rows($result);
var_dump($result);*/

以上就介绍了 singleton单例模式，包括了方面的内容，希望对PHP教程有兴趣的朋友有所帮助。