工厂模式(C++)
2015-12-23 22:20
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http://www.cnblogs.com/cxjchen/p/3143633.html
http://www.cnblogs.com/jiese/p/3154669.htmlhttp://blog.csdn.net/wuzhekai1985/article/details/6660462
http://www.cnblogs.com/onlycxue/p/3428075.html
下面就来看代码。首先,要看一下没有进行过优化的代码,这个代码是打算建立一个迷宫(Maze),迷宫的元素是墙、房间、门。它们都是MapSite的子类。同时一个房间有四个方向,有可能是墙也有可能是门。
#include <iostream> using namespace std; enum Direction { North, East, South, West, }; class MapSite { public: virtual void Enter() = 0; }; class Room : public MapSite { public: Room(int roomNo):_roomNumber(roomNo) {}; MapSite *GetSide(Direction) const; virtual void SetSide(Direction direction, MapSite *) { cout << "Set the " << _roomNumber << " room " << direction << " side." << endl; }; int GetRoomNo() { return _roomNumber; }; virtual void Enter() { cout << "Enter the Room." << endl; }; private: MapSite *_sides[4]; int _roomNumber; }; class Wall : public MapSite { public: Wall() {}; virtual void Enter() { cout << "Enter the wall." << endl; }; }; class Door : public MapSite { public: Door(Room* = 0, Room* = 0) {}; virtual void Enter() { cout << "Enter the door." << endl; }; Room *OtherSideFrom(Room*) {}; private: Room *_room1; Room *_room2; bool _isOpen; }; class Maze { public: Maze() {}; void AddRoom(Room* room) { cout << "Add the room" << room->GetRoomNo() << "." << endl; }; Room* RoomNo(int) const{}; }; class MazeGame { public: Maze *CreateMaze(); }; Maze* MazeGame::CreateMaze() { Maze* aMaze = new Maze; Room* r1 = new Room(1); Room* r2 = new Room(2); Door* theDoor = new Door(r1, r2); aMaze->AddRoom(r1); aMaze->AddRoom(r2); r1->SetSide(North, new Wall); r1->SetSide(East, theDoor); r1->SetSide(South, new Wall); r1->SetSide(West, new Wall); r2->SetSide(North, new Wall); r2->SetSide(East, new Wall); r2->SetSide(South, new Wall); r2->SetSide(West, theDoor); return aMaze; } int main() { MazeGame mygame; mygame.CreateMaze(); return 0; } 这个源码就是普通的实现方式。按照工厂模式进行修改之后的代码如下: #include <iostream> using namespace std; enum Direction { North, East, South, West, }; class MapSite { public: virtual void Enter() = 0; }; class Room : public MapSite { public: Room(int roomNo):_roomNumber(roomNo) {}; MapSite *GetSide(Direction) const; virtual void SetSide(Direction direction, MapSite *) { cout << "Set the " << _roomNumber << " room " << direction << " side." << endl; }; int GetRoomNo() { return _roomNumber; }; virtual void Enter() { cout << "Enter the Room." << endl; }; private: MapSite *_sides[4]; int _roomNumber; }; class Wall : public MapSite { public: Wall() {}; virtual void Enter() { cout << "Enter the wall." << endl; }; }; class Door : public MapSite { public: Door(Room* = 0, Room* = 0) {}; virtual void Enter() { cout << "Enter the door." << endl; }; Room *OtherSideFrom(Room*) {}; private: Room *_room1; Room *_room2; bool _isOpen; }; class Maze { public: Maze() {}; void AddRoom(Room* room) { cout << "Add the room" << room->GetRoomNo() << "." << endl; }; Room* RoomNo(int) const{}; }; class MazeFactory { public: MazeFactory() {}; virtual Maze* MakeMaze() const { return new Maze; }; virtual Wall* MakeWall() const { return new Wall; }; virtual Room* MakeRoom(int n) const { return new Room(n); }; virtual Door* MakeDoor(Room* r1, Room* r2) const { return new Door(r1, r2); }; }; class MazeGame { public: Maze* CreateMaze(MazeFactory &factory) { Maze* aMaze = factory.MakeMaze(); Room* r1 = factory.MakeRoom(1); Room* r2 = factory.MakeRoom(2); Door* theDoor = factory.MakeDoor(r1, r2); aMaze->AddRoom(r1); aMaze->AddRoom(r2); r1->SetSide(North, factory.MakeWall()); r1->SetSide(East, theDoor); r1->SetSide(South, factory.MakeWall()); r1->SetSide(West, factory.MakeWall()); r2->SetSide(North, factory.MakeWall()); r2->SetSide(East, factory.MakeWall()); r2->SetSide(South, factory.MakeWall()); r2->SetSide(West, theDoor); return aMaze; }; }; int main() { MazeGame mygame; MazeFactory factory; mygame.CreateMaze(factory); return 0; } 对比这两个源码就会发现,实现的功能是完全相同的,只不过第二种实现采用了工厂模式。设计模式既然好,肯定有它的好处,那我们接下来看看,如果是对这个程序进行扩展,要修改迷宫为房间里可以有炸弹的迷宫的时候,我们在采用了工厂模式之后,需要进行哪些修改。 #include <iostream> using namespace std; enum Direction { North, East, South, West, }; class MapSite { public: virtual void Enter() = 0; }; class Room : public MapSite { public: Room(int roomNo):_roomNumber(roomNo) {}; MapSite *GetSide(Direction) const; virtual void SetSide(Direction direction, MapSite *) { cout << "Set the " << _roomNumber << " room " << direction << " side." << endl; }; int GetRoomNo() { return _roomNumber; }; virtual void Enter() { cout << "Enter the Room." << endl; }; private: MapSite *_sides[4]; int _roomNumber; }; class BombRoom : public Room { public: BombRoom(int num):Room(num) { _roomNum = num; }; virtual void SetSide(Direction direction, MapSite *) { cout << "Set the " << _roomNum << " bomb room " << direction << " side." << endl; }; private: int _roomNum; }; class Wall : public MapSite { public: Wall() {}; virtual void Enter() { cout << "Enter the wall." << endl; }; }; class Door : public MapSite { public: Door(Room* = 0, Room* = 0) {}; virtual void Enter() { cout << "Enter the door." << endl; }; Room *OtherSideFrom(Room*) {}; private: Room *_room1; Room *_room2; bool _isOpen; }; class Maze { public: Maze() {}; void AddRoom(Room* room) { cout << "Add the room" << room->GetRoomNo() << "." << endl; }; Room* RoomNo(int) const{}; }; class MazeFactory { public: MazeFactory() {}; virtual Maze* MakeMaze() const { return new Maze; }; virtual Wall* MakeWall() const { return new Wall; }; virtual Room* MakeRoom(int n) const { return new Room(n); }; virtual Door* MakeDoor(Room* r1, Room* r2) const { return new Door(r1, r2); }; }; class BombMazeFactory : public MazeFactory { public: virtual Room* MakeRoom(int n) const { return new BombRoom(n); }; }; class MazeGame { public: Maze* CreateMaze(MazeFactory &factory) { Maze* aMaze = factory.MakeMaze(); Room* r1 = factory.MakeRoom(1); Room* r2 = factory.MakeRoom(2); Door* theDoor = factory.MakeDoor(r1, r2); aMaze->AddRoom(r1); aMaze->AddRoom(r2); r1->SetSide(North, factory.MakeWall()); r1->SetSide(East, theDoor); r1->SetSide(South, factory.MakeWall()); r1->SetSide(West, factory.MakeWall()); r2->SetSide(North, factory.MakeWall()); r2->SetSide(East, factory.MakeWall()); r2->SetSide(South, factory.MakeWall()); r2->SetSide(West, theDoor); return aMaze; }; }; int main() { MazeGame mygame; // MazeFactory factory; BombMazeFactory factory; mygame.CreateMaze(factory); return 0; } 可以看出改动量很小,而且可以随时把代码改回原来的生成普通迷宫的情况。
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