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 {
$sql = ‘DELETE FROM ‘ . $this->_config[‘tablename'] . ‘
WHERE heartbeat _config[‘cookie_timeout']) . ‘'‘;
$this->_mysqli->query($sql);
}
}
public function __destruct()
{
$this->_save();
$this->_gc();
$this->_mysqli->close();
}
}

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.

PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

PHP makes it easy to create interactive web content. 1) Dynamically generate content by embedding HTML and display it in real time based on user input or database data. 2) Process form submission and generate dynamic output to ensure that htmlspecialchars is used to prevent XSS. 3) Use MySQL to create a user registration system, and use password_hash and preprocessing statements to enhance security. Mastering these techniques will improve the efficiency of web development.

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.


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