设计模式C++学习笔记之十三（Decorator装饰模式）

装饰模式，动态地给一个对象添加一些额外的职责。就增加功能来说，Decorator模式相比生成子类更为灵活。

13.1.解释

main()，老爸

ISchoolReport，成绩单接口

CFourthGradeSchoolReport，四年级成绩单

ReportDecorator，成绩单装饰器基类

HighScoreDecorator，最高分装饰器

SortDecorator，班级排名装饰器

说明：对“四年级成绩单”进行装饰，ReportDecorator必然有一个private变量指向ISchoolReport。

注意：

看代码：

// Decorator.cpp//主程序

#include "stdafx.h"

#include "ISchoolReport.h"

#include "FouthGradeSchoolReport.h"

#include "SugarFouthGradeSchoolReport.h"

#include "HighScoreDecorator.h"

#include "SortDecorator.h"

#include <iostream>

using std::cout;

using std::endl;

void DoIt()

{

ISchoolReport *psr = new CSugarFouthGradeSchoolReport();

psr->Report();//看成绩单

psr->Sign("老三");//很开心，就签字了

delete psr;

}

void DoNew()

{

cout << "----------分部分进行装饰----------" << endl;

ISchoolReport *psr = new CFouthGradeSchoolReport();//原装成绩单

//

ISchoolReport *pssr = new CSortDecorator(psr);//又加了成绩排名的说明

ISchoolReport *phsr = new CHighScoreDecorator(pssr);//加了最高分说明的成绩单

phsr->Report();//看成绩单

phsr->Sign("老三");//很开心，就签字了



//先装饰哪个不重要，顺序已经在装饰内部确定好，但一定要调用最后一个装饰器的接口。

//ISchoolReport *phsr = new CHighScoreDecorator(psr);//加了最高分说明的成绩单

//ISchoolReport *pssr = new CSortDecorator(phsr);//又加了成绩排名的说明

//pssr->Report();//看成绩单

//pssr->Sign("老三");//很开心，就签字了

delete pssr;

delete phsr;

delete psr;

}

int _tmain(int argc, _TCHAR* argv[])

{

//在装饰之前，可以用继承的办法，来进行简单的修饰

DoIt();

//但如果需要修饰的项目太多呢？或者装饰的项目不是固定的，继承显然会变得更复杂

DoNew();

_CrtSetDbgFlag(_CRTDBG_LEAK_CHECK_DF | _CRTDBG_ALLOC_MEM_DF);

_CrtDumpMemoryLeaks();

return 0;

}

//ISchoolReport.h

#pragma once

#include <iostream>

using std::string;

class ISchoolReport

{

public:

ISchoolReport(void)

{

}

virtual ~ISchoolReport(void)

{

}

virtual void Report() = 0;

virtual void Sign(string name) = 0;

};

//FouthGradeSchoolReport.h

#pragma once

#include "ischoolreport.h"

class CFouthGradeSchoolReport :

public ISchoolReport

{

public:

CFouthGradeSchoolReport(void);

~CFouthGradeSchoolReport(void);

void Report();

void Sign(string name);

};

//FouthGradeSchoolReport.cpp

#include "StdAfx.h"

#include "FouthGradeSchoolReport.h"

#include <iostream>

using std::cout;

using std::endl;

using std::string;

CFouthGradeSchoolReport::CFouthGradeSchoolReport(void)

{

}

CFouthGradeSchoolReport::~CFouthGradeSchoolReport(void)

{

}

void CFouthGradeSchoolReport::Report()

{

cout << "尊敬的XXX家长：" << endl;

cout << "......" << endl;

cout << "语文62 数学65 体育98 自然63" << endl;

cout << "......" << endl;

cout << " 家长签名：" << endl;

}

void CFouthGradeSchoolReport::Sign(string name)

{

cout << "家长签名为：" << name.c_str() << endl;

}

//ReportDecorator.h

#pragma once

#include "ischoolreport.h"

class CReportDecorator :

public ISchoolReport

{

public:

CReportDecorator(ISchoolReport *psr);

virtual ~CReportDecorator(void);

void Report();

void Sign(string name);

private:

ISchoolReport *m_pSchoolReport;

};

//ReportDecorator.cpp

#include "StdAfx.h"

#include "ReportDecorator.h"

#include <iostream>

using std::string;

CReportDecorator::CReportDecorator(ISchoolReport *psr)

{

this->m_pSchoolReport = psr;

}

CReportDecorator::~CReportDecorator(void)

{

}

void CReportDecorator::Report()

{

this->m_pSchoolReport->Report();

}

void CReportDecorator::Sign( string name )

{

this->m_pSchoolReport->Sign(name);

}

//HighScoreDecorator.h

#pragma once

#include "reportdecorator.h"

#include "ISchoolReport.h"

class CHighScoreDecorator :

public CReportDecorator

{

public:

CHighScoreDecorator(ISchoolReport *psr);

~CHighScoreDecorator(void);

void Report();

private:

void ReportHighScore();

};

//HighScoreDecorator.cpp

#include "StdAfx.h"

#include "HighScoreDecorator.h"

#include <iostream>

using std::cout;

using std::endl;

CHighScoreDecorator::CHighScoreDecorator( ISchoolReport *psr ) : CReportDecorator(psr)

{

}

CHighScoreDecorator::~CHighScoreDecorator(void)

{

}

void CHighScoreDecorator::Report()

{

this->ReportHighScore();

this->CReportDecorator::Report();

}

void CHighScoreDecorator::ReportHighScore()

{

cout << "这次考试语文最高是75， 数学是78， 自然是80" << endl;

}

//SortDecorator.h

#pragma once

#include "reportdecorator.h"

#include "ISchoolReport.h"

class CSortDecorator :

public CReportDecorator

{

public:

CSortDecorator(ISchoolReport *psr);

~CSortDecorator(void);

void Report();

private:

void ReportSort();

};

//SortDecorator.cpp

#include "StdAfx.h"

#include "SortDecorator.h"

#include <iostream>

using std::cout;

using std::endl;

CSortDecorator::CSortDecorator( ISchoolReport *psr ) : CReportDecorator(psr)

{

}

CSortDecorator::~CSortDecorator(void)

{

}

void CSortDecorator::ReportSort()

{

cout << "我是排名第38名..." << endl;

}

void CSortDecorator::Report()

{

this->CReportDecorator::Report();

this->ReportSort();

}



这也是一个比较简单的模式，属于行为型模式。