魔术方法__sleep 和 __wakeup

感觉序列化和反序列化用得倒是比较少了，而json_encode和json_decode用得相对多，都是转化成串，进行入库、传输等。json更方便，但是序列化和反序列化结合这两个魔术方法使用倒还行
<?php 
/**
 *                     魔术方法__sleep() 和  __wakeup()
 *      __sleep(): serialize()序列化之前调用，返回一个需要保存变量名数组。一般用来保存部分属性，节省空间 
 *      __wakeup():unserialize() 反序列化之前调用，无返回值，一般进行一个动作
 */
class Test{
	public $s = ‘hehe‘;
	public $a = ‘world‘;
	
	public function __sleep(){
		return array(‘a‘);//序列化只保存a
	}
	
	public function __wakeup(){
		$this->a = ‘hello‘;//反序列化时进行a值的修改动作
	}
}

$m = new Test();
$n = serialize($m);
$m = unserialize($m);
var_dump($m);
?>

<?php
class Connection 
{
    protected $link;
    private $server, $username, $password, $db;
    
    public function __construct($server, $username, $password, $db)
    {
        $this->server = $server;
        $this->username = $username;
        $this->password = $password;
        $this->db = $db;
        $this->connect();
    }
    
    private function connect()
    {
        $this->link = mysql_connect($this->server, $this->username, $this->password);
        mysql_select_db($this->db, $this->link);
    }
    
    public function __sleep()
    {
        return array(‘server‘, ‘username‘, ‘password‘, ‘db‘);
    }
    
    public function __wakeup()
    {
        $this->connect();
    }
}
?>