【初學設計模式】Decorator (裝飾)

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類圖：

代碼實作：

類聲明：

/********************************************************************

File: decorator.h

Author: blackboy [email protected]

Purpose: 裝飾模式

Created: 2011-03-16

Modified: 2011-03-16 19:48

*********************************************************************/

#ifndef __DECORATOR_H__

#define __DECORATOR_H__

namespace blackboycpp

{

//

class Component

{

public:

virtual void Operation() = 0;

};

class ConcreteComponent : public Component

{

public:

virtual void Operation();

};

//

class Decorator : public Component

{

public:

Decorator();

Decorator(Component*);

virtual void Operation();

private:

Component* _component;

};

class ConcreteDecoratorA : public Decorator

{

public:

ConcreteDecoratorA();

ConcreteDecoratorA(Component*);

void Operation();

private:

void AddedState();

};

class ConcreteDecoratorB : public Decorator

{

public:

ConcreteDecoratorB();

ConcreteDecoratorB(Component*);

void Operation();

private:

void AddedBehavior();

};

}

#endif

類實作：

#include <iostream>

#include "decorator.h"

namespace blackboycpp

{

//

void ConcreteComponent::Operation()

{

std::cout << "ConcreteComponent::Operation()/n";

}

//

Decorator::Decorator()

{

std::cout << "Decorator::Decorator()/n";

_component = 0;

}

Decorator::Decorator(Component* p)

{

std::cout << "Decorator::Decorator(Component*)/n";

_component = p;

}

void Decorator::Operation()

{

std::cout << "Decorator::Operation()/n";

_component->Operation();

}

//

ConcreteDecoratorA::ConcreteDecoratorA() : Decorator()

{

std::cout << "ConcreteDecoratorA::ConcreteDecoratorA()/n";

}

ConcreteDecoratorA::ConcreteDecoratorA(Component* p) : Decorator(p)

{

std::cout << "ConcreteDecoratorA::ConcreteDecoratorA(Component*)/n";

}

void ConcreteDecoratorA::Operation()

{

std::cout << "ConcreteDecoratorA::Operation()/n";

Decorator::Operation();

AddedState();

}

void ConcreteDecoratorA::AddedState()

{

std::cout << "ConcreteDecoratorA::AddedState()/n";

}

//

ConcreteDecoratorB::ConcreteDecoratorB() : Decorator()

{

std::cout << "ConcreteDecoratorB::ConcreteDecoratorB()/n";

}

ConcreteDecoratorB::ConcreteDecoratorB(Component* p) : Decorator(p)

{

std::cout << "ConcreteDecoratorB::ConcreteDecoratorB(Component*)/n";

}

void ConcreteDecoratorB::Operation()

{

std::cout << "ConcreteDecoratorB::Operation()/n";

Decorator::Operation();

AddedBehavior();

}

void ConcreteDecoratorB::AddedBehavior()

{

std::cout << "ConcreteDecoratorB::AddedBehavior()/n";

}

}

main()：

#include <cstdlib>

#include "decorator.h"

using namespace blackboycpp;

int main(int argc, char** argv)

{

Component* component = new ConcreteComponent;

ConcreteDecoratorA* decoratorA = new ConcreteDecoratorA(component);

ConcreteDecoratorB* decoratorB = new ConcreteDecoratorB(decoratorA);

decoratorB->Operation();

delete decoratorB;

delete decoratorA;

delete component;

system("pause");

return 0;

}