<?php
/**
* php设计模式 单例模式
* site http://www.jbxue.com
*/
class Fruit {
private static $instanceMap = array();
//protected getter for singleton instances
protected static function getSingleton($className)
{
//保证单例模式 并且不能从控制器实例化和克隆
if(!isset(self::$instanceMap[$className]))
{
$object = new $className;
//Make sure this object inherit from Singleton
if($object instanceof Fruit)
{
self::$instanceMap[$className] = $object;
var_dump($object);
}
else
{
throw SingletonException("Class '$className' do not inherit from Singleton!");
}
}
return self::$instanceMap[$className];
}
//protected constructor to prevent outside instantiation
protected function __construct(){
}
//denie cloning of singleton objects
public final function __clone(){
trigger_error('It is impossible to clone singleton', E_USER_ERROR);
}
}
class Apple extends Fruit {
protected $rndId;
public function __construct(){
$this->rndId = rand();
}
public function whatAmI(){
echo 'I am a Apple('.$this->rndId.')<br />';
}
public static function getInstance(){
//echo get_class();
return Fruit::getSingleton(get_class());
}
}
class GreenApple extends Apple {
public function whatAmI(){
echo 'I am a GreenApple('.$this->rndId.')<br />';
}
public static function getInstance(){
return Fruit::getSingleton(get_class());
}
}
$apple1 = Apple::getInstance();
//var_dump($apple1);
$apple2 = GreenApple::getInstance();
$apple1->whatAmI();// should echo 'I am a Apple(some number)
$apple2->whatAmI();// should echo 'I am a GreenApple(some number)
$apple1 = Apple::getInstance();
$apple2 = GreenApple::getInstance();
//保证单例模式
$apple1->whatAmI();// should echo 'I am a Apple(same number as above)
$apple2->whatAmI();// should echo 'I am a GreenApple(same number as above)
// $a = clone $apple1;// this should fail
// $b = clone $apple2;// this should fail
?>
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