$s = serialize($_SESSION); //序列化对象a
$fp = fopen("sessionInfo", "w");//以"w"方式打开一文件并获得文件句柄,请在此注意目录属性.
fputs($fp, $s);//写入文件
fclose($fp);//关闭文件句柄
$us = implode("", @file("sessionInfo"));
$_SESSION = unserialize($us);