session_set_save_handler实例

<?php/* * usage as:** date_default_timezone_set("PRC");* set_session_mysql("localhost:3306", "root", "", "db");* session_start();* * #session table* CREATE TABLE `session` (  `id` varchar(100) NOT NULL DEFAULT '',  `value` mediumblob NOT NULL,  `ctime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,  PRIMARY KEY (`id`)) ENGINE=MyISAM DEFAULT CHARSET=utf8; */$session_mysql_conn = null;$session_mysql_host = null;$session_mysql_user = null;$session_mysql_pwd = null;$session_mysql_db = null;$session_mysql_flag = false;function open($save_path, $session_name){global $session_mysql_host;global $session_mysql_user;global $session_mysql_pwd;global $session_mysql_db;if(null == $session_mysql_host || null == $session_mysql_user|| null == $session_mysql_db)return false;global $session_mysql_conn;$session_mysql_conn = mysql_connect($session_mysql_host, $session_mysql_user, $session_mysql_pwd);if(false == $session_mysql_conn)return (false);if(false == mysql_select_db($session_mysql_db, $session_mysql_conn)){mysql_close($session_mysql_conn);$session_mysql_conn = null;return (false);}return(true);}function close(){return(true);}function read($id){global $session_mysql_conn;if(null == $session_mysql_conn)return null;$select_sql = "select value from session where id = '$id'";$result = mysql_query($select_sql, $session_mysql_conn);if(false == $result)return null;if(0 == mysql_num_rows($result))return null;$row = mysql_fetch_row($result);if(empty($row))return null; $res = $row[0];mysql_free_result($result);//echo "session_mysql_read:$id = $res </br>";return $res;}function write($id, $sess_data){//echo "session_mysql_write $id = $sess_data </br>";global $session_mysql_conn;global $session_mysql_flag;if(null == $session_mysql_conn)return false;$value = mysql_real_escape_string($sess_data);$write_sql="update session set value = '$value' where id = '$id'";if(false == $session_mysql_flag){$select_sql = "select count(id) from session where id = '$id'";$result = mysql_query($select_sql, $session_mysql_conn);if(false == $result)return false;$row = mysql_fetch_row($result);if(empty($row))return false;if($row[0] == 0){$write_sql="insert into session (id,value) values ('$id', '$value')";}else{$session_mysql_flag = true;}}return mysql_query($write_sql, $session_mysql_conn);}function destroy($id){global $session_mysql_conn;if(null == $session_mysql_conn)return false;mysql_close($session_mysql_conn);$session_mysql_conn = null;}function gc($maxlifetime){global $session_mysql_conn;if(null == $session_mysql_conn)return false;$t = time() - $maxlifetime;$d = date("Y-m-d h:i:s",$t);$delete_sql = "delete from session where ctime < '$d'";return mysql_query($delete_sql, $session_mysql_conn);}function set_session_mysql($s_mysql_host, $s_mysql_user, $s_mysql_pwd, $s_mysql_db){global $session_mysql_host;global $session_mysql_user;global $session_mysql_pwd;global $session_mysql_db;$session_mysql_host = $s_mysql_host;$session_mysql_user = $s_mysql_user;$session_mysql_pwd = $s_mysql_pwd;$session_mysql_db = $s_mysql_db;session_set_save_handler("open", "close", "read", "write", "destroy", "gc");}?>