设计模式之---简单工厂模式
简单工厂模式:到底要实例化哪个对象,将来会不会增加实例化对象,这时可以考虑用一个单独的类来创造实例的过程,这就是工厂。
以一个2元操作运算来说明:
operator类:
[cpp]
#pragma once
template <class T>
class COperator
{
public:
COperator(void){};
virtual ~COperator(void){};
virtual T GetResult(T NumberA,T NumberB);
};
#include "Operator.h"
template <class T>
T COperator<T>::GetResult(T NumberA,T NumberB)
{
T result=0;
return result;
}
加法类:
[cpp]
#pragma once
#include "Operator.h"
template <class T>
class CAddOperator:public COperator<T>
{
public:
CAddOperator(void){};
~CAddOperator(void){};
virtual T GetResult(T NumberA,T NumberB);
};
#include "AddOperator.h"
template <class T>
T CAddOperator<T>::GetResult(T NumberA,T NumberB)
{
T result;
result = NumberA + NumberB;
return result;
}
减法类:
[cpp]
#pragma once
#include "operator.h"
template <class T>
class CSubOperator :public COperator<T>
{
public:
CSubOperator(void){};
~CSubOperator(void){};
virtual T GetResult(T NumberA,T NumberB);
};
#include "SubOperator.h"
template <class T>
T CSubOperator<T>::GetResult(T NumberA,T NumberB)
{
T result= NumberA -NumberB ;
return result;
}
乘法类:
[cpp]
#pragma once
#include "operator.h"
template <class T>
class CMulOperator :public COperator<T>
{
public:
CMulOperator(void){};
~CMulOperator(void){};
virtual T GetResult(T NumberA,T NumberB);
};
#include "Mul.h"
template <class T>
T CMulOperator<T>::GetResult(T NumberA,T NumberB)
{
T result = NumberA * NumberB;
return result;
}
除法类:
[cpp]
#pragma once
#include "operator.h"
template <class T>
class CDivOperator :public COperator<T>
{
public:
CDivOperator(void){};
~CDivOperator(void){};
virtual T GetResult(T NumberA,T NumberB);
};
#include "Div.h"
#include <assert.h>
template <class T>
T CDivOperator<T>::GetResult(T NumberA,T NumberB)
{
assert( NumberB != 0);
T result = NumberA/NumberB;
return result;
}
接下来是简单工厂类,创建具体类的实例
[cpp]
#pragma once
#include "Operator.h"
#include "Operator.cpp"
#include "AddOperator.h"
#include "AddOperator.cpp"
#include "Div.h"
#include "Div.cpp"
#include "SubOperator.h"
#include "SubOperator.cpp"
#include "Mul.h"
#include "Mul.cpp"
template <class T>
class CFactory
{
public:
CFactory(void){};
~CFactory(void){};
COperator<T>* CreateOperator(const char strOpe);
};
#include "Factory.h"
template <class T>
COperator<T>* CFactory<T>::CreateOperator(const char strOpe)
{
COperator<T> *pOpe = NULL ;
switch(strOpe)
{
case '+':
pOpe = new CAddOperator<T>;
break;
case '-':
pOpe = new CSubOperator<T>;
break;
case '*':
pOpe=new CMulOperator<T>;
break;
case '/':
pOpe=new CDivOperator<T>;
break;
default:
break;
}
return pOpe;
}
在实际应用时可以简单的调用:
[cpp]
// SimpleFactory.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include "Factory.h"
#include "Factory.cpp"
#include <iostream>
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
CFactory<double> *pFac=new CFactory<double>;
COperator<double>* pOpe=NULL;
double result;
pOpe=pFac->CreateOperator('+');
if(pOpe!=NULL)
{
result = pOpe->GetResult(2,3);
cout<<"2 + 3 = "<<result<<endl;
delete pOpe;
}
pOpe=pFac->CreateOperator('-');
if(pOpe!=NULL)
{
result = pOpe->GetResult(2,3);
cout<<"2 - 3 = "<<result<<endl;
delete pOpe;&n
补充:软件开发 , C++ ,