Python实现享元模式的示例代码

class TreeType:
    def __init__(self, name, color, texture):
        self.name = name
        self.color = color
        self.texture = texture

    def draw(self, canvas, x, y):
        print(f"在({x}, {y})位置，画一个{self.color}颜色的{self.name}，纹理是{self.texture}。")

class TreeFactory:
    _tree_types = {}

    @staticmethod
    def get_tree_type(name, color, texture):
        key = (name, color, texture)
        if not TreeFactory._tree_types.get(key):
            print("创建一个新的TreeType。")
            TreeFactory._tree_types[key] = TreeType(name, color, texture)
        else:
            print("复用已有的TreeType。")
        return TreeFactory._tree_types[key]

class Tree:
    def __init__(self, x, y, name, color, texture):
        self.x = x
        self.y = y
        self.tree_type = TreeFactory.get_tree_type(name, color, texture)

    def draw(self, canvas):
        self.tree_type.draw(canvas, self.x, self.y)

class Forest:
    def __init__(self):
        self.trees = []

    def plant_tree(self, x, y, name, color, texture):
        tree = Tree(x, y, name, color, texture)
        self.trees.append(tree)

    def draw(self, canvas):
        for tree in self.trees:
            tree.draw(canvas)

if __name__ == "__main__":
    forest = Forest()
    forest.plant_tree(1, 2, "松树", "绿色", "粗糙")
    forest.plant_tree(2, 3, "松树", "绿色", "粗糙")
    forest.plant_tree(3, 5, "橡树", "棕色", "平滑")

    forest.draw("画布")

class ConfigDataFactory:
    _config_data = {}

    @staticmethod
    def get_config_data(key):
        if key not in ConfigDataFactory._config_data:
            # 假设这里从数据库或文件系统加载配置数据
            data = f"加载配置数据 {key}"
            ConfigDataFactory

._config_data[key] = data
            print("配置数据被加载。")
        else:
            print("复用已有的配置数据。")
        return ConfigDataFactory._config_data[key]

# 客户端代码
if __name__ == "__main__":
    config1 = ConfigDataFactory.get_config_data("app_settings")
    config2 = ConfigDataFactory.get_config_data("app_settings")

    print(config1)
    print(config2)