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decorator模式

黑色天�� — Fri, 16 Jan 2009 07:58:00 GMT

1 适用�?br>\• 在不影响其他对象的情况下�Q�以动态、透明的方式给单个对象��d��一些职责，如：加密层，解密层�?br>• 处理那些可能偶尔才会用到的特性接�?br>• 当不能采用生成子�cȝ��Ҏ��q�行扩充时。一�U�情冉|��Q�可能有大量独立的扩展，为支�?br>每一�U�组合将产生大量的子�c�，使得子类数目呈爆炸性增�?

#include "stdafx.h"
#include <iostream>
using namespace std;

class Component            //被装饰者抽象类
{
public:
    virtual void Draw() = 0;
};
class Decorator : public Component //被装饰者基�c?/span>
{
public:
    Decorator(Component *c) : _component(c){}
    ~Decorator() {delete _component;}

    virtual void Draw() { if (_component) _component->Draw();}
private:
    Component *_component;
};
//////////////////////////////////////////////////////////////////////////
class MyComponent : public Component //被装饰�?/span>
{
public:
    virtual void Draw() {cout << "MyComponent::Draw()" << endl;}
};
//////////////////////////////////////////////////////////////////////////
class BorderDecorator : public Decorator //�Ҏ��装饰
{
public:
    BorderDecorator(Component *c) : Decorator(c){}
    virtual void Draw()
    {
        cout << "DrawBorder" << endl;
        Decorator::Draw();
    }
};
class ScrollDecorator : public Decorator //滚动条装�?/span>
{
public:
    ScrollDecorator(Component *c) : Decorator(c){}
    virtual void Draw()
    {
        cout << "DrawSrollbar" << endl;
        Decorator::Draw();
    }
};
int main()
{
    Component *c2 = new BorderDecorator(
        new MyComponent()); //装饰�Ҏ��的组�?/span>
    c2->Draw();
    delete c2;

    Component *c3 = new ScrollDecorator(
        new BorderDecorator(
        new MyComponent())); //同时装饰上边框和滚动条的�l��g
    c2->Draw();
    delete c3;

    system("pause");
    return 0;
}

黑色天�� 2009-01-16 15:58 发表评论

黑色天�� — Thu, 15 Jan 2009 06:01:00 GMT

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黑色天�� 2009-01-15 14:01 发表评论