[结构型模式] 装饰者模式的理解

我会带着你远行 2022-04-11 05:10 159阅读 0赞

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\[color=red\]\[b\]头文件\[/b\]\[/color\]

//DecoratorPattern.h
    
    #ifndef DECORATOR_PATTERN_H
    #define DECORATOR_PATTERN_H
    
    #include <Windows.h>
    #include <iostream>
    using namespace std;
    
    namespace DecoratorPattern
    {
       
        /*
        ** FileName     : DecoratorPatternDemo
        ** Author       : Jelly Young
        ** Date         : 2013/12/19
        ** Description  : More information, please go to http://www.jellythink.com
        */
    
        class Component
        {
       
        public:
            Component();
            virtual ~Component();
            virtual void Operation() = 0;
        };
    
        class ConcreteComponent : public Component
        {
       
        public:
            ConcreteComponent();
            virtual ~ConcreteComponent();
            virtual void Operation();
        };
    
        //
        //
        class Decorator : public Component
        {
       
        public:
            Decorator(Component* pComponent);
            virtual ~Decorator();
            virtual void Operation();
    
        protected:
            Component* m_pComponentObj;
        };
    
        class ConcreteDecoratorA : public Decorator
        {
       
        public:
            ConcreteDecoratorA(Component* pDecorator) ;
            virtual ~ConcreteDecoratorA();
    
            virtual void Operation();
    
            void  AddedBehavior();
        };
    
        class ConcreteDecoratorB : public Decorator
        {
       
        public:
            ConcreteDecoratorB(Component* pDecorator);
            virtual ~ConcreteDecoratorB();
    
            virtual void Operation();
            void  AddedBehavior();
        };
    
        //
        void DecoratorPattern_Test();
    }
    
    #endif

\[color=red\]\[b\]实现\[/b\]\[/color\]

#include "DecoratorPattern.h"
    
    namespace DecoratorPattern
    {
       
        Component::Component()
        {
       
        }
    
        Component::~Component()
        {
       
        }
    
        //
        //
        ConcreteComponent::ConcreteComponent()
        {
       
        }
    
        ConcreteComponent::~ConcreteComponent()
        {
       
        }
    
        void ConcreteComponent::Operation()
        {
       
            cout<<"I am no decoratored ConcreteComponent"<<endl;
        }
    
    
        //
        //
        Decorator::Decorator(Component *pComponent)
            : m_pComponentObj(pComponent)
        {}
    
        Decorator::~Decorator()
        {}
    
        void Decorator::Operation()
        {
       
            if (m_pComponentObj != NULL)
            {
       
                m_pComponentObj->Operation();
            }
        }
    
        //
        ConcreteDecoratorA::ConcreteDecoratorA(Component* pDecorator)
            : Decorator(pDecorator)
        {}
    
        ConcreteDecoratorA::~ConcreteDecoratorA()
        {}
    
        void ConcreteDecoratorA::Operation()
        {
       
            AddedBehavior();
            Decorator::Operation();
        }
        void  ConcreteDecoratorA::AddedBehavior()
        {
       
            cout<<"This is added behavior A."<<endl;
        }
    
        ConcreteDecoratorB::ConcreteDecoratorB(Component *pDecorator)
            : Decorator(pDecorator)
        {}
        ConcreteDecoratorB::~ConcreteDecoratorB()
        {}
        void ConcreteDecoratorB::Operation()
        {
       
            AddedBehavior();
            Decorator::Operation();
        }
        void ConcreteDecoratorB::AddedBehavior()
        {
       
            cout<<"This is added behavior B."<<endl;
        }
    
    
        //
        void DecoratorPattern_Test()
        {
       
            Component *pComponentObj = new ConcreteComponent();
            Decorator *pDecoratorAOjb = new ConcreteDecoratorA(pComponentObj);
            pDecoratorAOjb->Operation();
            cout<<"============================================="<<endl;
            Decorator *pDecoratorBOjb = new ConcreteDecoratorB(pComponentObj);
            pDecoratorBOjb->Operation();
            cout<<"============================================="<<endl;
            Decorator *pDecoratorBAOjb = new ConcreteDecoratorB(pDecoratorAOjb);
            pDecoratorBAOjb->Operation();
            cout<<"============================================="<<endl;
    
            delete pDecoratorBAOjb;
            pDecoratorBAOjb = NULL;
            delete pDecoratorBOjb;
            pDecoratorBOjb = NULL;
            delete pDecoratorAOjb;
            pDecoratorAOjb = NULL;
            delete pComponentObj;
            pComponentObj = NULL;
        }
    }

\[color=red\]\[b\]客户端\[/b\]\[/color\]

#include "DecoratorPattern.h"
    
    
    #include <iostream>
    using namespace std;
    using namespace DecoratorPattern;
    
    void main()
    {
       
        DecoratorPattern_Test();
    }

\[color=red\]\[b\]运行结果\[/b\]\[/color\]  
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