探索PHP面向对象编程中的设计模式

class Singleton {
    private static $instance;

    private function __construct() {}

    public static function getInstance() {
        if (!self::$instance) {
            self::$instance = new self();
        }
        return self::$instance;
    }
}

$singletonInstance = Singleton::getInstance();

class Product {
    private $name;

    public function __construct($name) {
        $this->$name = $name;
    }

    public function getName() {
        return $this->$name;
    }
}

class ProductFactory {
    public static function createProduct($name) {
        return new Product($name);
    }
}

$product = ProductFactory::createProduct("Example");
echo $product->getName();

class Subject implements SplSubject {
    private $observers = array();
    private $data;

    public function attach(SplObserver $observer) {
        $this->observers[] = $observer;
    }

    public function detach(SplObserver $observer) {
        $key = array_search($observer, $this->observers);
        if ($key !== false) {
            unset($this->observers[$key]);
        }
    }

    public function notify() {
        foreach ($this->observers as $observer) {
            $observer->update($this);
        }
    }

    public function setData($data) {
        $this->data = $data;
        $this->notify();
    }

    public function getData() {
        return $this->data;
    }
}

class Observer implements SplObserver {
    private $id;

    public function __construct($id) {
        $this->id = $id;
    }

    public function update(SplSubject $subject) {
        echo "Observer " . $this->id . " notified with data: " . $subject->getData() . "
";
    }
}

$subject = new Subject();
$observer1 = new Observer(1);
$observer2 = new Observer(2);

$subject->attach($observer1);
$subject->attach($observer2);

$subject->setData("Example data");