Serialization is the process of converting a variable to a string that can be saved or transmitted, and deserialization is the conversion of the string to the original variable at the appropriate time. These two processes combine to easily store and transfer data, making programs more maintainable.
1. Serialize and Unserialize functions
These two are common functions for serializing and deserializing data in PHP.
Copy Code code as follows:
<?php
$a = Array (' A ' => ' Apple ', ' B ' => ' banana ', ' C ' => ' coconut ');
Serializing an array of
$s = serialize ($a);
Echo $s;
Output result: a:3:{s:1: "a"; S:5: "Apple"; s:1: "B"; S:6: "Banana"; s:1: "C"; s:7: "Coconut";
Echo ' <br/><br/> ';
Deserialization
$o = Unserialize ($s);
Print_r ($o);
Output result Array ([a] => Apple [b] => Banana [C] => Coconut)
?>
Problems may occur when array values contain characters such as double quotes, single quotes, or colons, which are deserialized. An ingenious technique to overcome this problem is to use Base64_encode and Base64_decode.
Copy Code code as follows:
$obj = Array ();
Serialization of
$s = Base64_encode (serialize ($obj));
Deserialization
$original = Unserialize (Base64_decode ($s));
However, the Base64 encoding will increase the length of the string. To overcome this problem, you can use it with gzcompress.
Defines a function to serialize an object
function My_serialize ($obj)
{
Returnbase64_encode (Gzcompress (Serialize ($obj)));
}
Deserialization
function My_unserialize ($txt)
{
Returnunserialize (Gzuncompress (Base64_decode ($txt)));
}
2. Json_encode and Json_decode
Using the JSON format for serialization and deserialization is a good choice:
Using Json_encode and Json_decode format output is much faster than the serialize and unserialize formats.
The JSON format is readable.
The JSON format is smaller than the result of the serialize return data.
The JSON format is open and portable. It can also be used in other languages.
Copy Code code as follows:
$a = Array (' A ' => ' Apple ', ' B ' => ' banana ', ' C ' => ' coconut ');
Serializing an array of
$s = json_encode ($a);
Echo $s;
Output result: {"a": "Apple", "B": "Banana", "C": "Coconut"}
Echo ' <br/><br/> ';
Deserialization
$o = Json_decode ($s);
In the above example, the Json_encode output length is obviously shorter than the serialize output length in the previous example.
3. Var_export and Eval
The Var_export function outputs the variable as a string; eval executes the string as a PHP code, deserializing the contents of the original variable.
Copy Code code as follows:
$a = Array (' A ' => ' Apple ', ' B ' => ' banana ', ' C ' => ' coconut ');
Serializing an array of
$s = Var_export ($a, true);
Echo $s;
Output results: Array (' A ' => ' Apple ', ' B ' => ' banana ', ' C ' => ' coconut ',)
Echo ' <br/><br/> ';
Deserialization
Eval (' $my _var= '. $s. ';');
Print_r ($my _var);
4. Wddx_serialize_value and WDDX Deserialize
The Wddx_serialize_value function can serialize an array variable and output it as an XML string.
Copy Code code as follows:
$a = Array (' A ' => ' Apple ', ' B ' => ' banana ', ' C ' => ' coconut ');
Serializing an array of
$s = wddx_serialize_value ($a);
Echo $s;
Output (view source of output String): <wddxpacket version= ' 1.0 ' >Echo ' <br/><br/> ';
Deserialization
$o = Wddx_deserialize ($s);
Print_r ($o);
Output result: Array ([a] => Apple [b] => Banana 1 => Coconut)
As you can see, there are more XML tag characters, resulting in a lot of space for serialization of this format.
Summary
All of the above functions perform correctly when serializing an array variable, but they are different when applied to an object. For example, Json_encode serialization of an object fails. Unserialize and Eval will have different effects when deserializing an object.
