Analyze various serialization and deserialization methods in PHP_PHP tutorial

Serialization is the process of converting variables into strings that can be saved or transmitted; deserialization is the process of converting this string into the original variable for use when appropriate. These two processes combine to easily store and transfer data, making the program more maintainable.
1. serialize and unserialize functions
These two are common functions for serializing and deserializing data in PHP.

Copy code The code is as follows:

$a = array('a'=> 'Apple' ,'b' => 'banana', 'c' => 'Coconut');
//Serialized array
$s = serialize($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 '

';
//Deserialization
$o = unserialize($ s);
print_r($o);
//Output result Array ( [a] => Apple [b] => banana [c] => Coconut )
?>

When array values ​​contain characters such as double quotes, single quotes, or colons, problems may occur after they are deserialized. To overcome this problem, a neat trick is to use base64_encode and base64_decode.

Copy code The code is as follows:

$obj = array();
//Serialization
$ s = base64_encode(serialize($obj));
//Deserialization
$original = unserialize(base64_decode($s));
But base64 encoding will increase the length of the string. To overcome this problem, it can be used with gzcompress.
//Define a function for serializing objects
function my_serialize($obj)
{
returnbase64_encode(gzcompress(serialize($obj)));
}
/ /Deserialize
function my_unserialize($txt)
{
returnunserialize(gzuncompress(base64_decode($txt)));
}

2. json_encode and json_decode
Using JSON format for serialization and deserialization is a good choice:
Using json_encode and json_decode format output is much faster than serialize and unserialize formats.
JSON format is readable.
JSON format returns smaller data than serialize.
JSON format is open and portable. Other languages ​​can use it as well.

Copy code The code is as follows:

$a = array('a'=> 'Apple' ,'b' => 'banana', 'c' => 'Coconut');

//Serialized array
$s = json_encode($a);
echo $s;
//Output result: {"a":"Apple","b":"banana","c":"Coconut"}
echo '

';
//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
var_export function outputs the variable as a string; eval executes the string as PHP code, and deserializes to get the original variable content.

Copy code The code is as follows:

$a = array('a'=> 'Apple' ,'b' => 'banana', 'c' => 'Coconut');

//Serialized array
$s = var_export($a, true);
echo $s;
//Output result: array ( 'a' => 'Apple', 'b' => 'banana', 'c' => 'Coconut', )
echo '

';
//Deserialization
eval('$my_var='. $s . ';');
print_r($my_var);

4. wddx_serialize_value and wddx deserialize
wddx_serialize_value function can serialize array variables and output them as XML strings.

Copy code The code is as follows:

$a = array('a'=> 'Apple' ,'b' => 'banana', 'c' => 'Coconut');

// Serialized array
$s = wddx_serialize_value($a);
echo $s;
//Output result (view the source code of the output string): < header/>Apple bananaCoconut
echo '

';
//Deserialization
$o = wddx_deserialize($s);
print_r($o);
//Output result: Array ( [a] => Apple [b] => banana 1 => Coconut )

It can be seen that there are many XML tag characters, resulting in this format The serialization still takes up a lot of space.
Summary
All the above functions can be executed normally when serializing array variables, but it is different when applied to objects. For example, json_encode serialized objects will fail. When deserializing objects, unserialize and eval will have different effects.

http://www.bkjia.com/PHPjc/327438.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/327438.htmlTechArticleSerialization is the process of converting variables into strings that can be saved or transmitted; deserialization is the process of Then convert this string into the original variable for use. The two processes combine...