1、有一个工厂，专门生产不同品牌的汽车。当有人需要从此工厂提货的时候，只需要告诉他，要什么品牌的，就可以了，并不关心这些车是怎么生产出来的。
2、以上方式，如果增加品牌的时候，也要修改工厂，有点麻烦。于是，把工厂也抽象了。
1的类图与实现：
首先，是通用的车
1 ///
2 /// @file Car.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:10:31
5 ///
6
7 #ifndef __CAR_H__
8 #define __CAR_H__
9
10 #include <iostream>
11
12 namespace marrs{
13
14 using std::cout;
15 using std::cerr;
16 using std::endl;
17
18 class Car
19 {
20 public:
21 Car() : b_IsRunning(0){}
22 virtual ~Car(){};
23 public:
24 virtual void Run() = 0;
25 virtual void Stop() = 0;
26 protected:
27 bool b_IsRunning;
28 };
29
30 }
31
32 #endif //__CAR_H__
然后是不同品牌的车，继承自Car
1 ///
2 /// @file Benz.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:20:54
5 ///
6
7 #ifndef __BENZ_H__
8 #define __BENZ_H__
9
10 #include "Car.h"
11
12 namespace marrs{
13
14 class Benz
15 : public Car
16 {
17 public:
18 ~Benz(){}
19 public:
20 void Run();
21 void Stop();
22 };
23
24 }
25
26 #endif //__BENZ_H__
1 ///
2 /// @file Benz.cc
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:21:54
5 ///
6
7 #include "Benz.h"
8
9 namespace marrs{
10
11 void Benz::Run()
12 {
13 if (b_IsRunning)
14 {
15 cerr << "Benz is running!" << endl;
16 }
17
18 cout << "Benz is going to running!" << endl;
19 b_IsRunning = true;
20 }
21
22 void Benz::Stop()
23 {
24 if (!b_IsRunning)
25 {
26 cerr << "Benz isn't running..." << endl;
27 }
28
29 cout << "Benz is going to stopping!" << endl;
30 b_IsRunning = false;
31 }
32
33 }
1 ///
2 /// @file Audi.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:20:54
5 ///
6
7 #ifndef __AUDI_H__
8 #define __AUDI_H__
9
10 #include "Car.h"
11
12 namespace marrs{
13
14 class Audi
15 : public Car
16 {
17 public:
18 ~Audi(){}
19 public:
20 void Run();
21 void Stop();
22 };
23
24 }
25
26 #endif//__AUDI_H__
1 ///
2 /// @file Audi.cc
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:21:54
5 ///
6
7 #include "Audi.h"
8
9 namespace marrs{
10
11 void Audi::Run()
12 {
13 if (b_IsRunning)
14 {
15 cerr << "Audi is running!" << endl;
16 }
17
18 cout << "Audi is going to running!" << endl;
19 b_IsRunning = true;
20 }
21
22 void Audi::Stop()
23 {
24 if (!b_IsRunning)
25 {
26 cerr << "Audi isn't running..." << endl;
27 }
28
29 cout << "Audi is going to stopping!" << endl;
30 b_IsRunning = false;
31 }
32
33 }
1 ///
2 /// @file Lamborghini.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:20:54
5 ///
6
7 #ifndef __LAMBORGHINI_H__
8 #define __LAMBORGHINI_H__
9
10 #include "Car.h"
11
12 namespace marrs{
13
14 class Lamborghini
15 : public Car
16 {
17 public:
18 ~Lamborghini(){}
19 public:
20 void Run();
21 void Stop();
22 };
23
24 }
25
26 #endif//__LAMBORGHINI_H__
1 ///
2 /// @file Lamborghini.cc
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:21:54
5 ///
6
7 #include "Lamborghini.h"
8
9 namespace marrs{
10
11 void Lamborghini::Run()
12 {
13 if (b_IsRunning)
14 {
15 cerr << "Lamborghini is running!" << endl;
16 }
17
18 cout << "Lamborghini is going to running!" << endl;
19 b_IsRunning = true;
20 }
21
22 void Lamborghini::Stop()
23 {
24 if (!b_IsRunning)
25 {
26 cerr << "Lamborghini isn't running..." << endl;
27 }
28
29 cout << "Lamborghini is going to stopping!" << endl;
30 b_IsRunning = false;
31 }
32
33 }
接着，有个生产工厂
1 ///
2 /// @file Factory.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:27:42
5 ///
6
7 #ifndef __FACTORY_H__
8 #define __FACTORY_H__
9
10
11 #include "Benz.h"
12 #include "Audi.h"
13 #include "Lamborghini.h"
14
15
16 enum Brand
17 {
18 EN_BRAND_CAR_BANZ = 0,
19 EN_BRAND_CAR_AUDI,
20 EN_BRAND_CAR_LAMBORGHINI,
21 };
22
23
24 namespace marrs{
25
26 using std::cout;
27 using std::endl;
28
29 class Factory
30 {
31 public:
32 Car * Produce(int int_brand);
33 void Reclaim(Car * car_brand);
34 };
35
36 }
37
38
39 #endif //__FACTORY_H__
1 ///
2 /// @file Factory.cc
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:39:05
5 ///
6
7 #include "Factory.h"
8
9 namespace marrs{
10
11 Car * Factory::Produce(int int_brand)
12 {
13 switch(int_brand)
14 {
15 case EN_BRAND_CAR_BANZ:
16 return new Benz;
17 case EN_BRAND_CAR_AUDI:
18 return new Audi;
19 case EN_BRAND_CAR_LAMBORGHINI:
20 return new Lamborghini;
21 default:break;
22 }
23 return NULL;
24 }
25
26 void Factory::Reclaim(Car * car_brand)
27 {
28 delete car_brand;
29 }
30
31 }
为了方便统一处理方式，我把车的销毁也放到工厂类里了。
1 ///
2 /// @file main.cc
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:40:59
5 ///
6
7 #include "Factory.h"
8
9 using namespace marrs;
10
11 int main()
12 {
13 Factory factory;
14
15 Car * car_first = factory.Produce(EN_BRAND_CAR_BANZ);
16 car_first->Run();
17 car_first->Stop();
18 factory.Reclaim(car_first);
19
20 Car * car_second = factory.Produce(EN_BRAND_CAR_AUDI);
21 car_second->Run();
22 car_second->Stop();
23 factory.Reclaim(car_second);
24
25 Car * car_third = factory.Produce(EN_BRAND_CAR_LAMBORGHINI);
26 car_third->Run();
27 car_third->Stop();
28 factory.Reclaim(car_third);
29
30 }
编译，运行
[ccx@ubuntu ~/object-oriented/Factory-Pattern]$>g++ * -o car_factory.exe
[ccx@ubuntu ~/object-oriented/Factory-Pattern]$>./car_factory.exe
Benz is going to running!
Benz is going to stopping!
Audi is going to running!
Audi is going to stopping!
Lamborghini is going to running!
Lamborghini is going to stopping!
2的类图与实现 （画图功底不行....略乱）
在1的基础之上，修改Factory
1 ///
2 /// @file Factory.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:27:42
5 ///
6
7 #ifndef __FACTORY_H__
8 #define __FACTORY_H__
9
10
11 #include "Car.h"
12
13 namespace marrs{
14
15 using std::cout;
16 using std::endl;
17
18 class Factory
19 {
20 public:
21 virtual ~Factory(){}
22 public:
23 virtual Car * Produce() = 0;
24 void Reclaim(Car * car_brand)
25 {
26 delete car_brand;
27 }
28 };
29
30 }
31
32
33 #endif //__FACTORY_H__
然后是不同的工厂
1 ///
2 /// @file Benz_Factory.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 21:21:58
5 ///
6
7 #ifndef __BENZ_FACTORY_H__
8 #define __BENZ_FACTORY_H__
9
10 #include "Factory.h"
11 #include "Benz.h"
12
13 namespace marrs{
14
15 class BenzFactory
16 : public Factory
17 {
18 public:
19 Car * Produce()
20 {
21 return new Benz;
22 }
23 };
24
25 }
26
27 #endif // __BENZ_FACTORY_H__
1 ///
2 /// @file Audi_Factory.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 21:21:58
5 ///
6
7 #ifndef __AUDI_FACTORY_H__
8 #define __AUDI_FACTORY_H__
9
10 #include "Factory.h"
11 #include "Audi.h"
12
13 namespace marrs{
14
15 class AudiFactory
16 : public Factory
17 {
18 public:
19 Car * Produce()
20 {
21 return new Audi;
22 }
23 };
24
25 }
26
27 #endif // __AUDI_FACTORY_H__
1 ///
2 /// @file Lamborghini_Factory.h
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 21:21:58
5 ///
6
7 #ifndef __LAMBORGHINI_FACTORY_H__
8 #define __LAMBORGHINI_FACTORY_H__
9
10 #include "Factory.h"
11 #include "Lamborghini.h"
12
13 namespace marrs{
14
15 class LamborghiniFactory
16 : public Factory
17 {
18 public:
19 Car * Produce()
20 {
21 return new Lamborghini;
22 }
23 };
24
25 }
26
27 #endif // __LAMBORGHINI_FACTORY_H__
最后修改main.cc
1 ///
2 /// @file main.cc
3 /// @author marrs(chenchengxi993@gmail.com)
4 /// @date 2017-08-12 20:40:59
5 ///
6
7 #include "Benz_Factory.h"
8 #include "Audi_Factory.h"
9 #include "Lamborghini_Factory.h"
10
11 using namespace marrs;
12
13 void BenzAction()
14 {
15 Factory * factory = new BenzFactory;
16 Car * car_first = factory->Produce();
17 car_first->Run();
18 car_first->Stop();
19 factory->Reclaim(car_first);
20 delete factory;
21 }
22
23 void AudiAction()
24 {
25 Factory * factory = new AudiFactory;
26 Car * car_first = factory->Produce();
27 car_first->Run();
28 car_first->Stop();
29 factory->Reclaim(car_first);
30 delete factory;
31 }
32
33 void LamborghiniAction()
34 {
35 Factory * factory = new LamborghiniFactory;
36 Car * car_first = factory->Produce();
37 car_first->Run();
38 car_first->Stop();
39 factory->Reclaim(car_first);
40 delete factory;
41 }
42
43
44 int main()
45 {
46 BenzAction();
47 AudiAction();
48 LamborghiniAction();
49
50 return 0;
51 }
编译，运行
[ccx@ubuntu ~/object-oriented/Factory-Pattern_2]$>g++ * -o car_Factory.exe
[ccx@ubuntu ~/object-oriented/Factory-Pattern_2]$>./car_Factory.exe
Benz is going to running!
Benz is going to stopping!
Audi is going to running!
Audi is going to stopping!
Lamborghini is going to running!
Lamborghini is going to stopping!