Python与设计模式--工厂模式

快餐点餐系统

想必大家一定见过类似于麦当劳自助点餐台一类的点餐系统吧。在一个大的触摸显示屏上，有3类可以选择的上餐品：汉堡等主餐、小食、饮料。当我们选择好自己需要的食物，支付完成后，订单就生成了。下面，我们用今天的 主角--工厂模式--来生成这些食物的逻辑主体。

首先我们主餐的生成（仅以两种汉堡为例）

# 工厂模式

class Burger():
    name = ""
    price = 0.0
    def getPrice(self):
        return self.price

    def setPrice(self,price):
        self.price = price

    def getName(self):
        return self.name

class cheeseBurger(Burger):
    def __init__(self):
        self.name = "cheese burger"
        self.price = 10.0

class spicyChickenBurger(Burger):
    def __init__(self):
        self.name = "spicy chicken burger"
        self.price = 15.0

class Snack():
    name = ""
    price = 0.0
    type = "SNACK"
    def getPrice(self):
        return self.price
    def setPrice(self,price):
        self.price = price
    def getName(self):
        return self.name

class chips(Snack):
    def __init__(self):
        self.name = "chips"
        self.price = 6.0

class chickenWings(Snack):
    def __init__(self):
        self.name = "chicken wings"
        self.price = 12.0

class Beverage():
    name = ""
    price = 0.0
    type = "BEVERAGE"
    def getPrice(self):
        return self.price
    def sefPrice(self,price):
        self.price = price
    def getName(self):
        return self.name

class coke(Beverage):
    def __init__(self):
        self.name = "coke"
        self.price = 4.0

class milk(Beverage):
    def __init__(self):
        self.name = "milk"
        self.price = 5.0

class foodFactory():
    type = ""
    def createFood(self,foodClass):
        print(self.type,"factory product a instance.")
        foodIns = foodClass()
        return foodIns

class burgerFactory(foodFactory):
    def __init__(self):
        self.type = "BURGER"

class snackFactory(foodFactory):
    def __init__(self):
        self.type = "SNACK"

class beverageFactory(foodFactory):
    def __init__(self):
        self.type = "BEVERAGE"

if __name__ == '__main__':
    burger_factory = burgerFactory()
    snack_factory = snackFactory()
    beverage_factory = beverageFactory()
    cheese_burger = burger_factory.createFood(cheeseBurger)
    print(cheese_burger.getName(),cheese_burger.getPrice())
    chicken_wings = snack_factory.createFood(chickenWings)
    print(chicken_wings.getName(),chicken_wings.getPrice())
    coke_drink = beverage_factory.createFood(coke)
    print(coke_drink.getName(),coke_drink.getPrice())

工厂模式的定义如下：定义一个用于创建对象的接口，让子类决定实例化哪一个类。