How to use PHP factory mode_PHP tutorial
Basic factory class
class MyObject{
//The object will be returned from the factory
}
class MyFactory{
public static function factory(){
return new MyObject():
}
}
$instance=MyFactory::factory();
Use factory class to parse image files
interface IImage{
function getHeight();
function getWidth();
function getData();
}
class Image_PNG implements IImage{
private $_width,$ _height,$_data;
public function __construct($file){
$this->_file=$file;
$this->_parse();
}
private function _parse(){
//Complete the parsing of PNG format
//Fill in $_width, $_height, $_data;
}
public function getWidth(){
return $this ->_width;
}
public function getHeight(){
return $this->_height;
}
public function getData(){
return $this-> ;_data;
}
}
class Image_JPEG implements IImage{
private $_width,$_height,$_data;
public function __construct($file){
$this-> ;_file=$file;
$this->_parse();
}
private function _parse(){
//Complete the parsing of JPEG format
//And fill in $ _width,$_height,$_data;
}
public function getWidth(){
return $this->_width;
}
public function getHeight(){
return $ this->_height;
}
public function getData(){
return $this->_data;
}
}
class ImageFactory{
public static function factory($file){
$pathParts=pathinfo($file);
switch (strtolower($pathParts['extension']))
{
case 'jpg':
$ ret=new Image_JPEG($file);
break;
case 'png':
$ret=new Image_PNG($file);
break;
default:
// There is a problem
}
if($ret instanceof IImage){
return $ret;
}else {
//There is a problem
}
}
}
//When calling the factory method using the image file name, different objects are obtained depending on the file type passed in.
//Call ImageFactoyr
$image=ImageFactory::factory('/path/to/my.jpg');
//$image is an instance of the Image_JPEG class
echo $image- >getWidth();
Use factory classes to solve database portability issues
In database applications, the factory pattern can work in the following two aspects.
. Make it easier for the software to support various database platforms to expand the user base
. If the software is used internally and the database needs to be modified, the application can be easily migrated to another platform
In the code, a database table named User is created to test it. This table defines a varchar type field named email
interface IDatabaseBindings{
public function userExists($email);
}
class PGSQL implements IDatabaseBindings{
protected $_connection;
public function __construct(){
$this->_connection=pg_connect('dbname=example_db');
}
public function userExists($email){
$emailEscaped=pg_escape_string ($email);
$query="select 1 from users where email='".$emailEscaped."'";
if($result=pg_query($query,$this->_connection)) {
return (pg_num_rows($result)>0)?true:false;
}else{
return false;
}
}
}
class MYSQL implements IDatabaseBindings{
protected $_connection;
public function __construct(){
$this->_connection=mysql_connect('localhost');
mysql_select_db('example_db',$this->_connection );
}
public function userExists($email){
$emailEscaped=mysql_real_escape_string($email);
$query="select 1 from users where email='".$emailEscaped." '";
if($result=mysql_query($query,$this->_connection)){
return (mysql_num_rows($result)>0)?true:false;
}else{
return false;
}
}
}
class DatabaseFactory{
public static function factory(){
$type=loadtypefromconfigfile();
switch ($ type){
case 'PGSQL':
return new PGSQL();
break;
case 'MYSQL':
return new MYSQL();
break;
}
}
}
The application does not have to know what type of database it is connected to, and will only deal directly with the instances returned by the factory based on the rules defined by the IDatabaseBindings interface.
//Call DatabaseFactoy
$db=DatabaseFactory::factory();
$db->userExists('person@example.com');

Effective methods to prevent session fixed attacks include: 1. Regenerate the session ID after the user logs in; 2. Use a secure session ID generation algorithm; 3. Implement the session timeout mechanism; 4. Encrypt session data using HTTPS. These measures can ensure that the application is indestructible when facing session fixed attacks.

Implementing session-free authentication can be achieved by using JSONWebTokens (JWT), a token-based authentication system where all necessary information is stored in the token without server-side session storage. 1) Use JWT to generate and verify tokens, 2) Ensure that HTTPS is used to prevent tokens from being intercepted, 3) Securely store tokens on the client side, 4) Verify tokens on the server side to prevent tampering, 5) Implement token revocation mechanisms, such as using short-term access tokens and long-term refresh tokens.

The security risks of PHP sessions mainly include session hijacking, session fixation, session prediction and session poisoning. 1. Session hijacking can be prevented by using HTTPS and protecting cookies. 2. Session fixation can be avoided by regenerating the session ID before the user logs in. 3. Session prediction needs to ensure the randomness and unpredictability of session IDs. 4. Session poisoning can be prevented by verifying and filtering session data.

To destroy a PHP session, you need to start the session first, then clear the data and destroy the session file. 1. Use session_start() to start the session. 2. Use session_unset() to clear the session data. 3. Finally, use session_destroy() to destroy the session file to ensure data security and resource release.

How to change the default session saving path of PHP? It can be achieved through the following steps: use session_save_path('/var/www/sessions');session_start(); in PHP scripts to set the session saving path. Set session.save_path="/var/www/sessions" in the php.ini file to change the session saving path globally. Use Memcached or Redis to store session data, such as ini_set('session.save_handler','memcached'); ini_set(

TomodifydatainaPHPsession,startthesessionwithsession_start(),thenuse$_SESSIONtoset,modify,orremovevariables.1)Startthesession.2)Setormodifysessionvariablesusing$_SESSION.3)Removevariableswithunset().4)Clearallvariableswithsession_unset().5)Destroythe

Arrays can be stored in PHP sessions. 1. Start the session and use session_start(). 2. Create an array and store it in $_SESSION. 3. Retrieve the array through $_SESSION. 4. Optimize session data to improve performance.

PHP session garbage collection is triggered through a probability mechanism to clean up expired session data. 1) Set the trigger probability and session life cycle in the configuration file; 2) You can use cron tasks to optimize high-load applications; 3) You need to balance the garbage collection frequency and performance to avoid data loss.


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