php中__sleep和__wakeup

在php中，__sleep和___wakeup是兩個分別自物件序列化前後分別調用的方法， 
其中__sleep在一個物件序列化前調用，它不接收任何參數，但會返回數組，這裡可以要放置哪些屬性需要序列化，例如下面的例子： 

class Customer {
 private $name;
 private $credit_card_number; 
 
public function setName($name) {
 $this->name = $name;
 }
 
public function getName() {
 return $this->name;
 }
 
public function setCC($cc) {
 $this->credit_card_number = $cc;
 }
 
public function getCC() {
 return $this->credit_card_number;
 }
 
public function __sleep() {
 return array(“name”); //只有name会序列化 }
 
}
 
$c = new Customer();
 $c->setName(“Stuard”);
 $c->setCC(“456789″);
 
$data = serialize($c).”\n”;
 echo $data.”\n”;
 
Output:
 O:8:”Customer”:1:{s:14:” Customer name”;s:5:”Stuard”;}

上面在序列化前，__sleep中指定了只有name屬性會序列化，而creaditcard不會。

    而__wakeup則相反，它是在反序列化前觸發的，例如下面例子： 

class Customer {
 private $name;
 private $credit_card_number; 
 
public function setName($name) {
 $this->name = $name;
 }
 
public function getName() {
 return $this->name;
 }
 
public function setCC($cc) {
 $this->credit_card_number = $cc;
 }
 
public function getCC() {
 return $this->credit_card_number;
 }
 
public function __sleep() {
 return array(“name”);
 }
 
public function __wakeup() {
 if($this->name == “Stuart”) {
  //重新在数据库中获得 
 $this->credit_card_number = “1234567890123456″;
 }
 }
 }
 
$c = new Customer();
 $c->setName(“Stuart”);
 $c->setCC(“1234567890123456″);
 
$data = serialize($c).”\n”;
 var_dump(unserialize($data));
 
Output:
 object(Customer)#2 (2) {
 ["name:private"]=>
 string(5) “Stuart”
 ["credit_card_number:private"]=>
 string(16) ’1234567890123456³
 }

上面的程式碼中，因為序列化時使用了__sleep,沒把creadit cardnumber屬性序列化，因此在反序列化unserialize呼叫前，會先呼叫__wakeup方法，例如這裡可以重新在資料庫中取得數據，再此進行操作