PHP面向?qū)ο蟪绦蛟O(shè)計(jì)之對(duì)象克隆clone和魔術(shù)方法__clone()用法分析

destinationObject = clone targetObject;

?php
class Person{
  var $name;
  var $sex;
  var $age;
  function __construct($name, $sex, $age){
    $this->name = $name;
    $this->sex = $sex;
    $this->age = $age;
  }
  function say(){
    echo "我的名字：" . $this->name . "，性別：" . $this->sex . "，年齡：" .$this->age . "br />";
  }
}
$person1 = new Person("張三三", "男", 23);
$person2 = clone $person1;  //使用clone關(guān)鍵字克隆/復(fù)制對(duì)象，創(chuàng)建一個(gè)對(duì)象的副本
$person3 = $person1;  //這不是復(fù)制對(duì)象，而是為對(duì)象多復(fù)制出一個(gè)訪問(wèn)該對(duì)象的引用
$person1->say();  //調(diào)用原對(duì)象中的說(shuō)話方式，打印原對(duì)象中的全部屬性值
$person2->say();  //調(diào)用副本對(duì)象中的說(shuō)話方式，打印克隆對(duì)象中的全部屬性值
$person3->say();  //調(diào)用原對(duì)象中的說(shuō)話方式，打印原對(duì)象中的全部屬性值
?>

?php
class Person{
  var $name;
  var $sex;
  var $age;
  function __construct($name, $sex, $age){
    $this->name = $name;
    $this->sex = $sex;
    $this->age = $age;
  }
  function say(){
    echo "我的名字：" . $this->name . "，性別：" . $this->sex . "，年齡：" .$this->age . "br />";
  }
  function __clone(){
    $this->name = "李四四";  //為副本對(duì)象中的name屬性重新賦值
    $this->age = 10;  //為副本對(duì)象中的age屬性重新賦值
  }
}
$person1 = new Person("張三三", "男", 23);
$person2 = clone $person1; //創(chuàng)建一個(gè)對(duì)象的副本，并自動(dòng)調(diào)用類中的__clone()方法
$person1->say();  //調(diào)用原對(duì)象中的說(shuō)話方式，打印原對(duì)象中的全部屬性值
$person2->say();  //調(diào)用副本對(duì)象中的說(shuō)話方式，打印克隆對(duì)象中的全部屬性值
?>

?php
class SingetonBasic {
  private static $instance; //靜態(tài)變量要私有化，防止類外修改
  private function __construct() {  //構(gòu)造函數(shù)私有化，類外不能直接新建對(duì)象
}
//private function __clone() {} //在__clone()前用private修飾，用來(lái)禁止克隆
public static function getInstance() { //公共的靜態(tài)方法,public——外部的接口，static——不使用對(duì)象而是通過(guò)類名訪問(wèn)
  if (!(self::$instance instanceof self)) { //私有靜態(tài)變量$instance為空
    self::$instance = new self(); //新建為自身的對(duì)象，并賦值給私有變量$instance
  }
  return self::$instance; //返回私有變量$instance
}
}
$a = SingetonBasic::getInstance();
$b = SingetonBasic::getInstance();
var_dump($a === $b);  //結(jié)果為：boolean true   a和b指向的是同一個(gè)對(duì)象
$c = clone $a;
var_dump($a === $c); //結(jié)果為：boolean false   a和c指向的不是同一個(gè)對(duì)象
?>

private function __clone() {}  //在__clone()前用private修飾，用來(lái)禁止克隆