PHP设计模式-工厂方法模式

定义

工厂方法模式定义了一个创建对象的接口，但由子类决定要实例化的类是哪一个。工厂方法让类把实例化推迟到了子类。

工厂方法模式通过让子类(NYPizzaStore, ChicagoPizzaStore)决定该创建的对象(NYStyleCheesePizza,ChicagoCheesePizza)，来达到将对象创建的过程封装的目的。

类图

工厂模式定义

实例图

Creator Class

Product Class

实例

创建者

//创建者超类
abstruct class PizzaStore
{
    public function orderPizza($type)
    {
        $pizza = $this->createPizza($type);

        $pizza->prepare();
        $pizza->bake();
        $pizza->cut();
        $pizza->box();

        return $pizza;
    }

    abstract public function createPizza($type);
}

//参数化工厂方法
//具体创建者
class NYPizzaStore extends PizzaStore
{
    public function createPizza($type)
    {
        if($type == 'cheese') {
            $pizza = new NYStyleCheesePizza();
        }elseif($type == 'peppernoi') {
            $pizza = new NYStylePeppernoiPizza();
        }elseif($type == 'clam') {
            $pizza = new NYStyleClamPizza();
        }

        return $pizza;
    }
}

//具体创建者
class ChicagoPizzaStore extends PizzaStore
{
    public function createPizza($type)
    {
        if($type == 'cheese') {
            $pizza = new ChicagoStyleCheesePizza();
        }elseif($type == 'peppernoi') {
            $pizza = new ChicagoStylePeppernoiPizza();
        }elseif($type == 'clam') {
            $pizza = new ChicagoStyleClamPizza();
        }

        return $pizza;
    }
}

产品类

//产品超类
abstract class Pizza
{
    private $name;
    private $dough;
    private $sauce;
    private toppings = [];

    private function prepare()
    {
        echo "Preparing ".$this->name;
        echo "Tossing";
        ...
    }
    
    private function bake()
    {
        echo "bake";
    }

    private function cut()
    {
        echo "cut";
    }

    private function box()
    {
        echo "box";
    }

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

//具体产品
class NYStyleCheesePizza extends Pizza
{
    public function __construct()
    {
        $this->name = "NY Style Souce and Cheese Pizza";
        $this->dough = "NY dough";
        $this->sauce = "NY sauce";
        $this->toppings[] = "Cheese";
    }

    //也可以重写父类的方法 实现子类特有的制作工艺
}

测试

$nyStore = new NYPizzaStore();
$pizza = $nyStore->orderPizza("cheese");
echo $pizza->getName();