如何实现PHP独立Session数据库存储操作类

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直接上代码：

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 - $this->_config['cookie_timeout']) . ''';
//echo $sql;exit;
$result = $this->_mysqli->query($sql);
$session = $result->fetch_array(MYSQLI_ASSOC);

if ($session AND ($this->fetch_substr_ip($session['ipaddress']) == $this->fetch_substr_ip($this->_session_host)))
{
$gotsession = true;
$this->_vars = $session;
$this->_created = false;
}
}

if ($gotsession == false)
{
$this->_vars = $this->fetch_session();
$this->_created = true;
$gotsession = true;
}

if ($this->_created == false)
{
$this->set('lastactivity', date('Y-m-d H:i:s', TIMENOW));
$this->set('location', $_SERVER['REQUEST_URI']);
}

}

/**
* Builds an array that can be used to build a query to insert/update the session
*
* @return array Array of column name => prepared value
*/
private function _build_query_array()
{
$return = array();
foreach ($this->_db_fields AS $fieldname => $cleantype)
{
switch ($cleantype)
{
case self::TYPE_INT:
$cleaned = is_numeric($this->_vars["$fieldname"]) ? $this->_vars["$fieldname"] : intval($this->_vars["$fieldname"]);
break;
case self::TYPE_STR:
default:
$cleaned = "'" . addslashes($this->_vars["$fieldname"]) . "'";
}
$return["$fieldname"] = $cleaned;
}

return $return;
}

/**
* Sets a session variable and updates the change list.
*
* @param string Name of session variable to update
* @param string Value to update it with
*/
public function set($key, $value)
{
if ($this->_vars["$key"] != $value)
{
$this->_vars["$key"] = $value;
$this->_changes["$key"] = true;
}
}

public function get($key)
{
return $this->_vars["$key"];
}

public function unsetchangedvar($var)
{
if (isset($this->_changes["$var"]))
{
unset($this->_changes["$var"]);
}
}

/**
* Fetches a valid sessionhash value, not necessarily the one tied to this session.
*
* @return string 32-character sessionhash
*/
static function fetch_sessionhash()
{
return hash('md5′ , TIMENOW . rand(1, 100000) . uniqid() );
}

private function _init_config()
{
$registry = Zend_Registry::getInstance();
$config = $registry->get('config');
$this->_config['host'] = $config->database->params->host;
$this->_config['port'] = $config->database->params->port;
$this->_config['username'] = $config->database->params->username;
$this->_config['password'] = $config->database->params->password;
$this->_config['dbname'] = $config->database->params->dbname;
$this->_config['tablename'] = $config->database->session->tablename;

}

/**
* initialize database connection
*/
public function init_db()
{
if ($this->_db_inited)
{
return true;
}

//mysqli_report(MYSQLI_REPORT_OFF);

$this->_mysqli = new mysqli(
$this->_config['host'],
$this->_config['username'],
$this->_config['password'],
$this->_config['dbname'],
$this->_config['port']
);

/* check connection */
if (mysqli_connect_errno())
{

// printf("Connect failed: %sn", mysqli_connect_error());
// echo 'in ', __FILE__, ' on line ', __LINE__;
echo "{ success: false, errors: { reason: ' Connect failed: " . addslashes( mysqli_connect_error() ) . "' }}";
exit();

}

$this->_mysqli->query('set names latin1′);
$this->_db_inited = true;

return true;
}

/**
* Fetches an alternate IP address of the current visitor, attempting to detect proxies etc.
*
* @return string
*/
static function fetch_alt_ip()
{
$alt_ip = $_SERVER['REMOTE_ADDR'];

if (isset($_SERVER['HTTP_CLIENT_IP']))
{
$alt_ip = $_SERVER['HTTP_CLIENT_IP'];
}
else if (isset($_SERVER['HTTP_FROM']))
{
$alt_ip = $_SERVER['HTTP_FROM'];
}

return $alt_ip;
}

/**
* Returns the IP address with the specified number of octets removed
*
* @param string IP address
*
* @return string truncated IP address
*/
static function fetch_substr_ip($ip, $length = null)
{
return implode('.', array_slice(explode('.', $ip), 0, 4 - $length));
}

/**
* Fetches a default session. Used when creating a new session.
*
* @param integer User ID the session should be for
*
* @return array Array of session variables
*/
public function fetch_session($userid = 0)
{
$sessionhash = self::fetch_sessionhash();

$this->set_cookie('sessionhash', $sessionhash);

return array(
'crc32sid' => sprintf('%u', crc32($sessionhash)),
'sessionhash' => $sessionhash,
'idhash' => $this->_session_idhash,
'userid' => $userid,
'ipaddress' => $this->_session_host,
'lastactivity' => date('Y-m-d H:i:s', TIMENOW),
'location' => $_SERVER['REQUEST_URI'],
'loggedin' => $userid ? 1 : 0,
'heartbeat' => date('Y-m-d H:i:s', TIMENOW)
);
}

public function get_cookie($cookiename)
{
$full_cookiename = $this->_config['cookie_prefix'] . $cookiename;

if (isset($_COOKIE[$full_cookiename]))
{
return $_COOKIE[$full_cookiename];
}
else
{
return false;
}
}

public function set_cookie($name, $value = ", $permanent = 1, $allowsecure = true)
{

if ($permanent)
{
$expire = TIMENOW + 60 * 60 * 24 * 365;
}
else
{
$expire = 0;
}

if ($_SERVER['SERVER_PORT'] == '443′)
{
// we're using SSL
$secure = 1;
}
else
{
$secure = 0;
}

// check for SSL
$secure = ((REQ_PROTOCOL === 'https' AND $allowsecure) ? true : false);

$name = $this->_config['cookie_prefix'] . $name;
$filename = 'N/A';
$linenum = 0;

if (!headers_sent($filename, $linenum))
{ // consider showing an error message if there not sent using above variables?
if ($value == " AND strlen($this->_config['cookiepath']) > 1 AND strpos($this->_config['cookiepath'], '/') !== false)
{
// this will attempt to unset the cookie at each directory up the path.
// ie, cookiepath = /test/abc/. These will be unset: /, /test, /test/, /test/abc, /test/abc/
// This should hopefully prevent cookie conflicts when the cookie path is changed.
$dirarray = explode('/', preg_replace('#/+$#', ", $this->_config['cookiepath']));
$alldirs = ";
foreach ($dirarray AS $thisdir)
{
$alldirs .= "$thisdir";
if (!empty($thisdir))
{ // try unsetting without the / at the end
setcookie($name, $value, $expire, $alldirs, $this->_config['cookiedomain'], $secure);
}
$alldirs .= "/";
setcookie($name, $value, $expire, $alldirs, $this->_config['cookiedomain'], $secure);
}
}
else
{
setcookie($name, $value, $expire, $this->_config['cookiepath'], $this->_config['cookiedomain'], $secure);
}
}
else if (!DEBUG)
{
echo "can't set cookies";
}
}

private function _save()
{
$cleaned = $this->_build_query_array();

if ($this->_created)
{
//var_dump($cleaned);
# insert query
$this->_mysqli->query('
INSERT IGNORE INTO ' . $this->_config['tablename'] . '
(' . implode(',', array_keys($cleaned)) . ')
VALUES
(' . implode(',', $cleaned). ')
');
}
else
{
# update query
$update = array();

foreach ($cleaned AS $key => $value)
{
if (!empty($this->_changes["$key"]))
{
$update[] = "$key = $value";
}
}

if (sizeof($update) > 0)
{
$sql = 'UPDATE ' . $this->_config['tablename'] . '
SET ' . implode(', ', $update) . '
WHERE crc32sid = ' . sprintf('%u', crc32($this->_dbsessionhash)) . '
AND sessionhash = '' . $this->_dbsessionhash . ''';
//echo $sql;
$this->_mysqli->query($sql);
}
}
}

public function getOnlineUserNum()
{
$sql = '
SELECT count(*) as cnt
FROM ' . $this->_config['tablename'] . '
WHERE loggedin = 1
AND heartbeat > '' . date('Y-m-d H:i:s' ,TIMENOW - $this->_config['cookie_timeout']) . ''';

$result = $this->_mysqli->query($sql);
$row = $result->fetch_array(MYSQLI_ASSOC);
return $row['cnt'];
}

private function _gc()
{
$rand_num = rand(); # randow integer between 0 and getrandmax()
if ($rand_num < 100)
{
$sql = 'DELETE FROM ' . $this->_config['tablename'] . '
WHERE heartbeat < '' . date('Y-m-d H:i:s' ,TIMENOW - $this->_config['cookie_timeout']) . ''';

$this->_mysqli->query($sql);
}
}

public function __destruct()
{
$this->_save();
$this->_gc();
$this->_mysqli->close();
}

}

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