PHP serialization and deserialization

serialization

Serialization format

string serialize ( mixed $value )Copy the code

class CC {
    public $data;
    private $pass;
 
    public function __construct($data.$pass)
    {
        $this->data = $data;
        $this->pass = $pass; }}$number = 34;
$str = 'uusama';
$bool = true;
$null = NULL;
$arr = array('a'= > 1,'b'= > 2);$cc = new CC('uu'.true);
 
var_dump(serialize($number));
var_dump(serialize($str));
var_dump(serialize($bool));
var_dump(serialize($null));
var_dump(serialize($arr));
var_dump(serialize($cc));Copy the code

string(5) "i:34;"
string(13) "s:6:"uusama";"
string(4) "b:1;"
string(2) "N;"
string(30) "a:2:{s:1:"a"; i:1; s:1:"b"; i:2; }"
string(52) "O:2:"CC":2:{s:4:"data"; s:2:"uu"; s:8:" CC pass"; b:1; }"Copy the code

• String : s:size:value;
• Integer : i:value;
• Boolean: b:value; (Save 1 or 0)
• Null : N;
• Array: a:size:{key definition; value definition; (repeated per element)}
• Object: O:strlen(object name):object name:object size:{s:strlen(property name):property name:property definition; (repeated per property)}

Serialized object

• Will constants in objects be saved?
• If it is inherited, will the variables of the parent class be saved

class CB {
    public $CB_data = 'cb';
}
 
class CC extends CB{
    const SECOND = 60;
 
    public $data;
    private $pass;
 
    public function __construct($data.$pass)
    {
        $this->data = $data;
        $this->pass = $pass;
    }
 
    public function setPass($pass)
    {
        $this->pass = $pass; }}$cc = new CC('uu'.true);
 
var_dump(serialize($cc));Copy the code

string(75) "O:2:"CC":3:{s:4:"data"; s:2:"uu"; s:8:" CC pass"; b:1; s:7:"CB_data"; s:2:"cb"; }"Copy the code

Object serialization custom

public array __sleep ( void )Copy the code

• This method returns an array containing the names of all the variables in the object that should be serialized
• The method returns nothing, NULL is serialized, and an E_NOTICE level error is generated
• __sleep() cannot return the name of a private member of the parent class. Doing so produces an E_NOTICE level error. Only the Serializable interface can be used instead.
• It is used to clean up large objects to avoid storing redundant data

class User{
    const SITE = 'uusama';
 
    public $username;
    public $nickname;
    private $password;
 
    public function __construct($username.$nickname.$password)
    {
        $this->username = $username;
        $this->nickname = $nickname;
        $this->password = $password; } // Override the serialization call method publicfunction __sleep() {// return the name of the variable to serialize, filtering out the password variablereturn array('username'.'nickname'); }}$user = new User('uusama'.'uu'.'123456');
var_dump(serialize($user));Copy the code

string(67) "O:4:"User":2:{s:8:"username"; s:6:"uusama"; s:8:"nickname"; s:2:"uu"; }"Copy the code

Serialized object store

$user = new User('uusama'.'uu'.'123456');
$ser = serialize($user); // Save local file_put_contents('user.ser'.$ser);Copy the code

deserialization

Method of use

mixed unserialize ( string $str )Copy the code

• If the string passed is not deserializable, FALSE is returned and an E_NOTICE is generated
• Returns the converted value, which can be integer ‘ ‘float, string, array, or Object
• If the deserialized variable is an object, PHP automatically attempts to call the __wakeup() member function (if it exists) after successfully reconstructing the object.

class User{
    const SITE = 'uusama';
 
    public $username;
    public $nickname;
    private $password;
    private $order;
 
    public function __construct($username.$nickname.$password)
    {
        $this->username = $username;
        $this->nickname = $nickname;
        $this->password = $password; } // Define the deserialized method called publicfunction __wakeup()
    {
        $this->password = $this->username; }}$user_ser = 'O:4:"User":2:{s:8:"username"; s:6:"uusama"; s:8:"nickname"; s:2:"uu"; } ';
var_dump(unserialize($user_ser));Copy the code

object(User)# 1 (4) {
  ["username"]=>
  string(6) "uusama"
  ["nickname"]=>
  string(2) "uu"
  ["password":"User":private]=>
  string(6) "uusama"
  ["order":"User":private]=>
  NULL
}Copy the code

• The __wakeup() function is executed after the object is built, so $this->username is not empty
• When deserializing, variable values are matched and copied to the serialized object as much as possible

Processing of undefined classes

$user_ser = 'O:4:"User":2:{s:8:"username"; s:6:"uusama"; s:8:"nickname"; s:2:"uu"; } ';
var_dump(unserialize($user_ser));Copy the code

object(__PHP_Incomplete_Class)# 1 (3) {
  ["__PHP_Incomplete_Class_Name"]=>
  string(4) "User"
  ["username"]=>
  string(6) "uusama"
  ["nickname"]=>
  string(2) "uu"
}Copy the code

• Define functions such as __autoload() that specify the class definition file toload when an undefined class is found
• Unserialize_callback_func can be defined via php.ini, ini_set(), or.htaccess. It is called every time an undefined class is instantiated

// unserialize_callback_func available from PHP 4.2.0'unserialize_callback_func'.'mycallback'); // Set your callback functionfunction mycallback($classname) {// Just include the file with the class definition //$classname} // We recommend using the following function instead of __autoload() spl_autoload_register()function ($class_name) {// Dynamically load the definition file require_once for undefined classes$class_name . '.php';
});Copy the code

PHP predefined serialization interface Serializable

Serializable {
    abstract public string serialize ( void )
    abstract public mixed unserialize ( string $serialized)}Copy the code

class CB implements Serializable{

    public $CB_data = ' ';

    private $CB_password = 'ttt';

 

    public function setCBPassword($password)

    {

        $this->CB_password = $password;

    }

 

    public function serialize()

    {

        echo __METHOD__ . "\n";

        return serialize($this->CB_password);

    }

 

    public function unserialize($serialized)

    {

        echo __METHOD__ . "\n";

    }

}

 

class CC extends CB {

    const SECOND = 60;

 

    public $data;

    private $pass;

 

    public function __construct($data.$pass)

    {

        $this->data = $data;

        $this->pass = $pass;

    }

 

    public function __sleep() {// Outputs the method name calledecho __METHOD__ . "\n";

    }

 

    public function __wakeup() {// Outputs the method name calledecho __METHOD__ . "\n"; }}$cc = new CC('uu'.true);

$ser = serialize($cc);

var_dump($ser);

$un_cc = unserialize($ser);

var_dump($un_cc);

Copy the code

CB::serialize
string(24) "C:2:"CC":10:{s:3:"ttt"; }"
CB::unserialize
object(CC)# 2 (4) {
  ["data"]=>
  NULL
  ["pass":"CC":private]=>
  NULL
  ["CB_data"]=>
  string(0) ""
  ["CB_password":"CB":private]=>
  string(3) "ttt"
}Copy the code

digression

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