session_set_save_handler的调用过程是怎么样的？
<!--Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--><?php /**CREATE TABLE IF NOT EXISTS `sessions` ( `session` varchar(255) character set utf8 collate utf8_bin NOT NULL, `session_expires` int(10) unsigned NOT NULL default '0', `session_data` text collate utf8_unicode_ci, PRIMARY KEY (`session`)) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; */class Session { /** * a database connection resource * @var resource */ private static $_sess_db; /** * Open the session * @return bool */ public static function open() { if (self::$_sess_db = mysql_connect('localhost', 'root', '')) { return mysql_select_db('my_application', self::$_sess_db); } return false; } /** * Close the session * @return bool */ public static function close() { return mysql_close(self::$_sess_db); } /** * Read the session * @param int session id * @return string string of the sessoin */ public static function read($id) { $id = mysql_real_escape_string($id); $sql = sprintf("SELECT `session_data` FROM `sessions` WHERE `session` = '%s'", $id); if ($result = mysql_query($sql, self::$_sess_db)) { if (mysql_num_rows($result)) { $record = mysql_fetch_assoc($result); return $record['session_data']; } } return ''; } /** * Write the session * @param int session id * @param string data of the session */ public static function write($id, $data) { $sql = sprintf("REPLACE INTO `sessions` VALUES('%s', '%s', '%s')", mysql_real_escape_string($id), mysql_real_escape_string(time()), mysql_real_escape_string($data) ); return mysql_query($sql, self::$_sess_db); } /** * Destoroy the session * @param int session id * @return bool */ public static function destroy($id) { $sql = sprintf("DELETE FROM `sessions` WHERE `session` = '%s'", $id); return mysql_query($sql, self::$_sess_db); } /** * Garbage Collector * @param int life time (sec.) * @return bool * @see session.gc_divisor 100 * @see session.gc_maxlifetime 1440 * @see session.gc_probability 1 * @usage execution rate 1/100 * (session.gc_probability/session.gc_divisor) */ public static function gc($max) { $sql = sprintf("DELETE FROM `sessions` WHERE `session_expires` < '%s'", mysql_real_escape_string(time() - $max)); return mysql_query($sql, self::$_sess_db); }}//ini_set('session.gc_probability', 50);ini_set('session.save_handler', 'user');session_set_save_handler(array('Session', 'open'), array('Session', 'close'), array('Session', 'read'), array('Session', 'write'), array('Session', 'destroy'), array('Session', 'gc') );if (session_id() == "") session_start();//session_regenerate_id(false); //also works fineif (isset($_SESSION['counter'])) { $_SESSION['counter']++;} else { $_SESSION['counter'] = 1;}echo '<br/>SessionID: '. session_id() .'<br>Counter: '. $_SESSION['counter'];
