用設計模式固化你的C#程序(6-2)
Design Patterns: Solidify Your C# Application Architecture with Design Patterns中文版(尾篇二)
作者：Samir Bajaj
譯者：榮耀
state.h
#include "stdafx.h";
class State;
class VendingMachine;
class Start;
class Five;
class Ten;
class Fiftee;
class Twenty;
class State
{
public:
virtual void AddNickel(VendingMachine* vm) { }
virtual void AddDime(VendingMachine* vm) { }
virtual void AddQuarter(VendingMachine* vm) { }
protected:
virtual void ChangeState(VendingMachine* vm, State* s);
};
class VendingMachine
{
private:
State* state;
public:
VendingMachine();
void ChangeState(State* to);
void Vend();
void AddNickel();
void AddDime();
void AddQuarter();
};
class Start : public State
{
private:
static State* state;
public:
static State* Instance();
void AddNickel(VendingMachine* vm);
void AddDime(VendingMachine* vm);
void AddQuarter(VendingMachine* vm);
};
class Five : public State
{
private:
static State* state;
public:
static State* Instance();
void AddNickel(VendingMachine* vm);
void AddDime(VendingMachine* vm);
void AddQuarter(VendingMachine* vm);
};
class Ten : public State
{
private:
static State* state;
public:
static State* Instance();
void AddNickel(VendingMachine* vm);
void AddDime(VendingMachine* vm);
void AddQuarter(VendingMachine* vm);
};
class Fifteen : public State
{
private:
static State* state;
public:
static State* Instance();
void AddNickel(VendingMachine* vm);
void AddDime(VendingMachine* vm);
void AddQuarter(VendingMachine* vm);
};
class Twenty : public State
{
private:
static State* state;
public:
static State* Instance();
void AddNickel(VendingMachine* vm);
void AddDime(VendingMachine* vm);
void AddQuarter(VendingMachine* vm);
state.cpp
#include "stdafx.h";
#include "test.h";
#include
using namespace std;
void State::ChangeState(VendingMachine* vm, State* s)
{
vm->ChangeState(s);
}
VendingMachine::VendingMachine()
{
cout<<"The Vending Machine is now online: product costs 25c"< state = Start::Instance();
}
void VendingMachine::ChangeState(State* to)
{
state = to;
}
void VendingMachine::Vend()
{
file://發飲料
cout<<"Dispensing product...Thank you!"< }
void VendingMachine::AddNickel()
{
state->AddNickel(this);
}
void VendingMachine::AddDime()
{
state->AddDime(this);
}
void VendingMachine::AddQuarter()
{
state->AddQuarter(this);
}
State* Start::state = new Start();
State* Start::Instance()
{
// singleton 邏輯
cout<<"Credit: 0c"< return state;
}
void Start::AddNickel(VendingMachine* vm)
{
ChangeState(vm, Five::Instance());
}
void Start::AddDime(VendingMachine* vm)
{
ChangeState(vm, Ten::Instance());
}
void Start::AddQuarter(VendingMachine* vm)
{
vm->Vend();
}
State* Five::state = new Five();
State* Five::Instance()
{
// singleton邏輯
cout<<"Credit: 5c"< return state;
}
void Five::AddNickel(VendingMachine* vm)
{
ChangeState(vm, Ten::Instance());
}
void Five::AddDime(VendingMachine* vm)
{
ChangeState(vm, Fifteen::Instance());
}
void Five::AddQuarter(VendingMachine* vm)
{
vm->Vend();
ChangeState(vm, Start::Instance()); // no change returned :-)
}
State* Ten::state = new Ten();
State* Ten::Instance()
{
// singleton 邏輯
cout<<"Credit: 10c"< return state;
}
void Ten::AddNickel(VendingMachine* vm)
{
ChangeState(vm, Fifteen::Instance());
}
void Ten::AddDime(VendingMachine* vm)
{
ChangeState(vm, Twenty::Instance());
}
void Ten::AddQuarter(VendingMachine* vm)
{
vm->Vend();
ChangeState(vm, Start::Instance()); // no change returned :-)
}
State* Fifteen::state = new Fifteen();
State* Fifteen::Instance()
{
// singleton 邏輯
cout<<"Credit: 15c"< return state;
}
void Fifteen::AddNickel(VendingMachine* vm)
{
ChangeState(vm, Twenty::Instance());
}
void Fifteen::AddDime(VendingMachine* vm)
{
vm->Vend();
ChangeState(vm, Start::Instance());
}
void Fifteen::AddQuarter(VendingMachine* vm)
{
vm->Vend();
ChangeState(vm, Start::Instance()); // no change returned :-)
}
State* Twenty::state = new Twenty();
State* Twenty::Instance()
{
// singleton 邏輯
cout<<"Credit: 20c"< return state;
}
void Twenty::AddNickel(VendingMachine* vm)
{
vm->Vend();
ChangeState(vm, Start::Instance());
}
void Twenty::AddDime(VendingMachine* vm)
{
vm->Vend();
ChangeState(vm, Start::Instance());
}
void Twenty::AddQuarter(VendingMachine* vm)
{
vm->Vend();
ChangeState(vm, Start::Instance()); // no change returned :-)
}
int _tmain(int argc, _TCHAR* argv[])
{
int coin = 0;
VendingMachine* vm = new VendingMachine();
int i = 0;
while (i < 10) file://【譯注：對應的C#代碼是while(true)，為避免內存洩漏問題，改為如此。否則，永遠都不會執行後面四行@代碼】
{
cout<<"Insert a coin (5, 10, 25): ";
cin>>coin;
switch (coin)
{
case 5:
vm->AddNickel();
break;
case 10:
vm->AddDime();
break;
case 25:
vm->AddQuarter();
break;
default:
break;
}
i++;
}
delete Start::Instance();//@
delete Five::Instance();//@
delete Ten::Instance();//@
delete Fifteen::Instance();//@
return 0;
}
/*以下是某次運行時輸出結果：
The Vending Machine is now online: product costs 25c
Credit: 0c
Insert a coin <5, 10, 25>: 5
Credit: 5c
Insert a coin <5, 10, 25>: 10
Credit: 15c
Insert a coin <5, 10, 25>: 5
Credit: 20c
Insert a coin <5, 10, 25>: 5
Dispensing product...Thank you!
*/
】
