php session_set_save_handler 函数的用法(mysql)

db = &$db;
session_module_name('user'); //session文件保存方式，这个是必须的！除非在Php.ini文件中设置了
session_set_save_handler( 
array(&$this, 'open'), //在运行session_start()时执行
array(&$this, 'close'), //在脚本执行完成或调用session_write_close() 或 session_destroy()时被执行,即在所有session操作完后被执行
array(&$this, 'read'), //在运行session_start()时执行,因为在session_start时,会去read当前session数据
array(&$this, 'write'), //此方法在脚本结束和使用session_write_close()强制提交SESSION数据时执行
array(&$this, 'destroy'), //在运行session_destroy()时执行
array(&$this, 'gc') //执行概率由session.gc_probability 和 session.gc_divisor的值决定,时机是在open,read之后,session_start会相继执行open,read和gc
); 
session_start(); //这也是必须的，打开session，必须在session_set_save_handler后面执行
} 
function unserializes($data_value) { 
$vars = preg_split( 
'/([a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)\|/', 
$data_value, -1, PREG_SPLIT_NO_EMPTY | 
PREG_SPLIT_DELIM_CAPTURE 
); 
for ($i = 0; isset($vars[$i]); $i++) { 
$result[$vars[$i++]] = unserialize($vars[$i]); 
} 
return $result; 
}
function open($path, $name) { 
return true; 
} 
function close() { 
$this->gc($this->lasttime);
return true; 
} 
function read($SessionKey){
$sql = "SELECT uid FROM sessions WHERE session_id = '".$SessionKey."' limit 1"; 
$query =$this->db->query($sql);
if($row=$this->db->fetch_array($query)){
return $row['uid'];
}else{
return ""; 
}
} 
function write($SessionKey,$VArray) { 
require_once(MRoot.DIR_WS_CLASSES .'db_mysql_class.php');
$db1=new DbCom();
// make a connection to the database... now
$db1->connect(DB_SERVER, DB_SERVER_USERNAME, DB_SERVER_PASSWORD, DB_DATABASE);
$db1->query("set names utf8");
$this->db=$db1;
$SessionArray = addslashes($VArray);
$data=$this->unserializes($VArray);  
$sql0 = "SELECT uid FROM sessions WHERE session_id = '".$SessionKey."' limit 1"; 
$query0 =$this->db->query($sql0);
if($this->db->num_rows($query0)<=0){
if (isset($data['webid']) && !empty($data['webid'])) { 
$this->db->query("insert into `sessions` set `session_id` = '$SessionKey',uid='".$data['webid']."',last_visit='".time()."'");
}  
return true;
}else{
/*$sql = "update `sessions` set "; 
if(isset($data['webid'])){
$sql .= "uid = '".$data['webid']."', " ;
}
$sql.="`last_visit` = null " 
. "where `session_id` = '$SessionKey'"; 
$this->db->query($sql); */
return true; 
}  
} 
function destroy($SessionKey) { 
$this->db->query("delete from `sessions` where `session_id` = '$SessionKey'"); 
return true; 
} 
function gc($lifetime) {
$this->db->query("delete from `sessions` where unix_timestamp(now()) -`last_visit` > '".$this->lasttime."'");
return true;
} 
} 
?>