享元模式

Posted 2021-01-17 agang-php

class flower:
    def __init__(self):
        pass
    def buy(self):
        pass

class ShareFlower(flower):
    def __init__(self, color):
        self.color = color

    def buy(self):
        print(‘一朵 %s 的鲜花‘ % (self.color))

class Factory():
    def __init__(self):
        self.share = dict()

    def getFlower(self, color):
        if color not in self.share:
            print(‘not in‘)
            self.share[color] = ShareFlower(color)
        return self.share[color]

class UnShareFlower(flower):
    def __init__(self, color):
        self.color = color

    def buy(self):
        print(‘不共享一朵 %s 的鲜花‘ % (self.color))

flower = Factory()
blue_flower = flower.getFlower(‘blue‘)
red_flower = flower.getFlower(‘red‘)
red_flower1 = flower.getFlower(‘red‘)
red_flower2 = flower.getFlower(‘red‘)
black_flower = UnShareFlower(‘blak‘)
blue_flower.buy()
red_flower.buy()
red_flower1.buy()
red_flower2.buy()
black_flower.buy()

单例模式是类级别的，一个类只能有一个对象实例；

享元模式是对象级别的，可以有多个对象实例，多个变量引用同一个对象实例；

享元模式主要是为了节约内存空间，提高系统性能，而单例模式主要为了可以共享数据；