直接上代碼：
復(fù)制代碼 代碼如下:
class DbSession
{

    const TYPE_INT = 1;
    const TYPE_STR = 2;

    /**
     * Database configration
     *
     * @var array
     */
    private $_config = array(
            ‘host' => '127.0.0.1′,
            ‘port' => 3306,
            ‘username' => ‘root',
            ‘password' => ‘root',
            ‘dbname' => ‘db_mylab',
        ‘tablename' => ‘t_sessions',
        ‘cookie_prefix' => ‘mylab_',
        ‘cookiepath' => ‘/',
        ‘cookiedomain' => ”,
        ‘cookie_timeout' => 900
    );

    /**
     * Table fields type array
     *
     * @var array
     */
    private  $_db_fields = array(
        ‘crc32sid'      => self::TYPE_INT,
                ‘sessionhash'   => self::TYPE_STR,
                ‘idhash'        => self::TYPE_STR,
                ‘userid'        => self::TYPE_INT,
                ‘ipaddress'     => self::TYPE_STR,
                ‘lastactivity'  => self::TYPE_STR,
                ‘location'      => self::TYPE_STR,
        ‘loggedin'      => self::TYPE_INT,
        ‘heartbeat'     => self::TYPE_STR
        );

        /**
         * db obj
         *
         * @var mysqli object
         */
    private $_mysqli = null;

    /**
     * Weather the session was created or existed previously
     *
     * @var bool
     */
    private $_created = false;

    /**
     * Array of changes.
     *
     * @var array
     */
    private $_changes = array();

    /**
     * @var bool
     */

    private $_db_inited = false;

    /**
     * session host
     *
     * @var string
     */
    private $_session_host = ”;

    /**
     * session idhash
     *
     * @var string
     */
    private $_session_idhash = ”;

    private $_dbsessionhash = ”;

    private $_vars = array();

        public function __construct()
        {
                $this->_dbsessionhash = addslashes($this->get_cookie(‘sessionhash'));

            $this->_session_host = substr($_SERVER[‘REMOTE_ADDR'], 0, 15);

            #This should *never* change during a session
            $this->_session_idhash = md5($_SERVER[‘HTTP_USER_AGENT'] . self::fetch_substr_ip(self::fetch_alt_ip()) );

            $this->_init_config();
            $this->init_db();

            $gotsession = false;

            if ($this->_dbsessionhash)
            {
                $sql = ‘
                        SELECT *
                        FROM ‘ . $this->_config[‘tablename'] . ‘
                        WHERE   crc32sid = ‘ . sprintf(‘%u', crc32($this->_dbsessionhash)) . ‘
                            AND sessionhash = '‘ . $this->_dbsessionhash . ‘'
                                AND idhash = '‘ . $this->_session_idhash . ‘'
                        AND heartbeat > '‘ . date(‘Y-m-d H:i:s' ,TIMENOW