C++ 装饰模式实现详解及示例代码

装饰模式是一种结构型设计模式，可以在不改变对象类的情况下，动态地给对象添加新的功能。该模式的核心思想是通过封装原始对象，以便在运行时动态地添加新的行为或状态。

以下是用 C++ 实现装饰模式的示例代码：

// Component接口类，定义了被装饰对象的基本操作 class Component { public: virtual void operation() = 0; };

// ConcreteComponent类，实现Component接口 class ConcreteComponent : public Component { public: void operation() { cout << 'ConcreteComponent operation.' << endl; } };

// Decorator类，继承Component接口，同时包含一个指向Component对象的指针 class Decorator : public Component { public: Decorator(Component* c) : component(c) {} void operation() { component->operation(); } protected: Component* component; };

// ConcreteDecoratorA类，实现Decorator接口，添加新的操作 class ConcreteDecoratorA : public Decorator { public: ConcreteDecoratorA(Component* c) : Decorator(c) {} void operation() { Decorator::operation(); cout << 'ConcreteDecoratorA operation.' << endl; } };

// ConcreteDecoratorB类，实现Decorator接口，添加新的操作 class ConcreteDecoratorB : public Decorator { public: ConcreteDecoratorB(Component* c) : Decorator(c) {} void operation() { Decorator::operation(); cout << 'ConcreteDecoratorB operation.' << endl; } };

// 客户端代码 int main() { // 创建ConcreteComponent对象 Component* c = new ConcreteComponent();

// 用ConcreteDecoratorA包装ConcreteComponent对象
Component* d1 = new ConcreteDecoratorA(c);

// 用ConcreteDecoratorB包装ConcreteDecoratorA对象
Component* d2 = new ConcreteDecoratorB(d1);

// 执行操作
d2->operation();

// 释放内存
delete d2;
delete d1;
delete c;

return 0;

}

输出结果：

ConcreteComponent operation. ConcreteDecoratorA operation. ConcreteDecoratorB operation.