设计模式- 装饰器模式（Decorator Pattern）结构|原理|优缺点|场景|示例

// 组件接口
interface Coffee {
    double getCost();
    String getDescription();
}
 
// 具体组件
class SimpleCoffee implements Coffee {
    @Override
    public double getCost() {
        return 10.0;
    }
 
    @Override
    public String getDescription() {
        return "Simple coffee";
    }
}
 
// 装饰器
abstract class CoffeeDecorator implements Coffee {
    protected Coffee decoratedCoffee;
 
    public CoffeeDecorator(Coffee decoratedCoffee) {
        this.decoratedCoffee = decoratedCoffee;
    }
 
    @Override
    public double getCost() {
        return decoratedCoffee.getCost();
    }
 
    @Override
    public String getDescription() {
        return decoratedCoffee.getDescription();
    }
}
 
// 具体装饰器
class MilkCoffee extends CoffeeDecorator {
    public MilkCoffee(Coffee decoratedCoffee) {
        super(decoratedCoffee);
    }
 
    @Override
    public double getCost() {
        return super.getCost() + 2.0;
    }
 
    @Override
    public String getDescription() {
        return super.getDescription() + ", with milk";
    }
}
 
class VanillaCoffee extends CoffeeDecorator {
    public VanillaCoffee(Coffee decoratedCoffee) {
        super(decoratedCoffee);
    }
 
    @Override
    public double getCost() {
        return super.getCost() + 3.0;
    }
 
    @Override
    public String getDescription() {
        return super.getDescription() + ", with vanilla";
    }
}
 
// 客户端代码
public class Client {
    public static void main(String[] args) {
        Coffee simpleCoffee = new SimpleCoffee();
        System.out.println(simpleCoffee.getDescription() + " costs " + simpleCoffee.getCost());  
        // 输出：Simple coffee costs 10.0
 
        Coffee milkCoffee = new MilkCoffee(simpleCoffee);
        System.out.println(milkCoffee.getDescription() + " costs " + milkCoffee.getCost());  
        // 输出：Simple coffee, with milk costs 12.0
 
        Coffee vanillaMilkCoffee = new VanillaCoffee(milkCoffee);
        System.out.println(vanillaMilkCoffee.getDescription() + " costs " + vanillaMilkCoffee.getCost());  
        // 输出：Simple coffee, with milk, with vanilla costs 15.0
    }
}

# 组件接口
class Coffee:
    def get_cost(self):
        raise NotImplementedError("Subclasses must implement this method")
 
    def get_description(self):
        raise NotImplementedError("Subclasses must implement this method")
 
# 具体组件
class SimpleCoffee(Coffee):
    def __init__(self):
        self.cost = 10
        self.description = "Simple coffee"
 
    def get_cost(self):
        return self.cost
 
    def get_description(self):
        return self.description
 
# 装饰器
class CoffeeDecorator(Coffee):
    def __init__(self, decorated_coffee: Coffee):
        self.decorated_coffee = decorated_coffee
 
    def get_cost(self):
        return self.decorated_coffee.get_cost()
 
    def get_description(self):
        return self.decorated_coffee.get_description()
 
# 具体装饰器
class MilkCoffee(CoffeeDecorator):
    def __init__(self, decorated_coffee: Coffee):
        super().__init__(decorated_coffee)
        self.cost = decorated_coffee.get_cost() + 2
        self.description = decorated_coffee.get_description() + ", with milk"
 
class VanillaCoffee(CoffeeDecorator):
    def __init__(self, decorated_coffee: Coffee):
        super().__init__(decorated_coffee)
        self.cost = decorated_coffee.get_cost() + 3
        self.description = decorated_coffee.get_description() + ", with vanilla"
 
# 客户端代码
def main():
    simple_coffee = SimpleCoffee()
    print(simple_coffee.get_description(), "costs", simple_coffee.get_cost())  # 输出：Simple coffee costs 10
 
    milk_coffee = MilkCoffee(simple_coffee)
    print(milk_coffee.get_description(), "costs", milk_coffee.get_cost())  # 输出：Simple coffee, with milk costs 12
 
    vanilla_milk_coffee = VanillaCoffee(milk_coffee)
    print(vanilla_milk_coffee.get_description(), "costs", vanilla_milk_coffee.get_cost())  # 输出：Simple coffee, with milk, with vanilla costs 15
 
if __name__ == "__main__":
    main()