php中_sleep跟_wakeup

php中__sleep和__wakeup
  在php中，__sleep和___wakeup是两个分别自对象序列化前和后分别调用的方法，
其中__sleep在一个对象序列化前调用，它不接收任何参数，但会返回数组，这里可以放置哪些属性需要序列化，比如下面的例子：

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属性会序列化，而creaditcard不会。

    而__wakeup则相反，它是在反序列化前触发的，比如下面例子：

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) ’1234567890123456? }

   上面的代码中，因为序列化时使用了__sleep,沒把creadit cardnumber属性序列化，因此在反序列化unserialize调用前，会先调用__wakeup方法，比如这里可以重新在数据库中取得数据，再此进行操作