PHP object-oriented guide (16) Serialization of objects_PHP tutorial

Serializing objects
Sometimes it is necessary to transmit an object over the network. In order to facilitate transmission, the entire object can be converted into a binary string.
When it reaches the other end, it can be restored to the original object. This process Call it serialization, just like we now want to transport a car to the United States by ship. Because the car is relatively large, we can disassemble the car into small parts, and then we They are transported to the United States by wheel, and then the parts are assembled back into the car.
There are two cases where we must serialize the object. The first case is to
serialize the object when transmitting it over the network. The second case is to write the object to a file or Serialization is used when it is a database.
There are two processes in serialization. One is serialization, which is to convert the object into a binary string. We use the
serialize() function to serialize an object, and the other is deserialization. , which is to convert the binary string converted from the object into an object. We use the unserialize() function to deserialize an object.
The parameter of the serialize() function in PHP is the object name, and the return value is a string. The string
returned by Serialize() has ambiguous meaning. Generally, we will not parse this string to get the object information. We only need Just pass the returned string
to the other end of the network or save it in the widget.
The unserialize() function in PHP is used to deserialize objects. The parameter of this function is the return value of the serialize() function.
The output is of course the reorganized object. Code snippet

Copy code The code is as follows:

class Person{
//The following is Person’s member attributes
var $name; //Person’s name
var $sex; //Person’s gender
var $age; //Person’s age
//Define a construction method The parameters are assigned attributes name $name, gender $sex and age $age
function __construct($name="", $sex="", $age=""){
$this->name =$name;
$this->sex=$sex;
$this->age=$age;
}
//The way this person can speak, tell his own Attribute
function say() {
echo "My name is: ".$this->name." Gender: ".$this->sex." My age is: ".$ this->age."
";
}
}
$p1=new Person("张三", "男", 20);
$p1_string=serialize( $p1); //Serialize an object and return a string
echo $p1_string."
"; //We usually do not parse serialized strings
$p2= unserialize($p1_string); //Deserialize a serialized string into an object $p2
$p2->say();
?>


Output result of the above example:

Code snippet
O:6:"Person":3:{s:4:"name";s:4:"Zhang San";s:3:"sex"; s:2:"Male";s:3:"age";i:20;}
My name is: Zhang San Gender: Male My age is: 20
There are two in php5 The magic methods __sleep() method and __wakeup() method, when the object is serialized, will call
a __sleep() method to complete some things before going to bed; and when waking up again, that is, by the binary When the string is reorganized into an object
, another function of PHP, __wakeup(), will be automatically called to do some actions that the object needs to do when it wakes up.
The __sleep() function does not accept any parameters, but returns an array containing the properties that need to be serialized. Attributes not included in
will be ignored during serialization. If there is no __sleep() method, PHP will save all attributes.
Code snippet

Copy code The code is as follows:

class Person{
/ /The following are the member attributes of the person
var $name; //The name of the person
var $sex; //The gender of the person
var $age; //The age of the person
//Definition A constructor parameter is assigned to the attributes name $name, gender $sex and age $age
function __construct($name="", $sex="", $age=""){
$this- >name=$name;
$this->sex=$sex;
$this->age=$age;
}
//The way this person can talk, say Expose your own attribute function say()
{
echo "My name is: ".$this->name." Gender: ".$this->sex." My age is: ".$this->age."
";
}
//When specifying serialization, serialize the $name and $age values ​​​​in the returned array, ignoring those not in the array Attributes of $sex
function __sleep() {
$arr=array("name", "age");
return($arr);
}
//Regenerate the object when, and reassign $age to 40
function __wakeup() {
$this->age = 40;
}
}
$p1=new Person("Zhang San" , "Male", 20);
//Serialize an object, return a string, call the __sleep() method, ignore the attributes not in the array $sex
$p1_string=serialize( $p1);
echo $p1_string."
"; //We usually do not parse serialized strings
$p2=unserialize($p1_string); //Deserialization formation Object $p2 reassigns $age to 40
$p2->say();
?>


The output value of the above example is:
Execution result
O:6:"Person":2:{s:4:"name";s:4:"Zhang San";s:3:" age";i:20;}
My name is: Zhang San Gender: My age is: 40

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