简单工厂不符合开闭原则，所以这里不把创建每个对象放在一个工厂里，而是把创建工厂抽象出来，每次创建一个具体对象由每个对象工厂自己常见，符合开闭原则。
1 #include<iostream>
2 using namespace std;
3 #include<string>
4
5 //简单工厂不符合开闭原则，所以这里不把创建每个水果对象放在一个工厂里，而是把创建工厂抽象出来，每次创建一个具体水果由每个对象工厂自己常见，达到开闭原则。
6
7 //抽象水果
8 class abstractFruit{
9 public:
10 virtual void showName()=0;
11 };
12 //苹果
13 class apple:public abstractFruit{
14 public:
15 virtual void showName()
16 {
17 cout<<"apple"<<endl;
18 }
19 };
20 //梨
21 class pear:public abstractFruit{
22 public:
23 virtual void showName()
24 {
25 cout<<"pear"<<endl;
26 }
27 };
28 //香蕉
29 class banana:public abstractFruit{
30 public:
31 virtual void showName()
32 {
33 cout<<"banana"<<endl;
34 }
35 };
36
37 //抽象水果工厂
38 class abstractFactory{
39 public:
40 virtual abstractFruit* createFruit()=0;
41 };
42
43 //苹果工厂
44 class appleFactory:public abstractFactory{
45 public:
46 virtual abstractFruit* createFruit(){
47 return new apple;
48 }
49 };
50
51 //梨工厂
52 class pearFactory:public abstractFactory{
53 public:
54 virtual abstractFruit* createFruit(){
55 return new pear;
56 }
57 };
58
59 //香蕉工厂
60 class bananaFactory:public abstractFactory{
61 public:
62 virtual abstractFruit* createFruit(){
63 return new banana;
64 }
65 };
66
67
68 int main()
69 {
70 //创建一个抽象工厂
71 abstractFactory *factory=NULL;
72 //创建一个抽象水果
73 abstractFruit* fruit=NULL;
74
75
76 //创建一个苹果
77 factory=new appleFactory;
78 fruit=factory->createFruit();
79 fruit->showName();
80 delete factory;
81 delete fruit;
82
83 //创建一个香蕉
84 factory=new bananaFactory;
85 fruit=factory->createFruit();
86 fruit->showName();
87 delete factory;
88 delete fruit;
89
90 //创建一个梨
91 factory=new pearFactory;
92 fruit=factory->createFruit();
93 fruit->showName();
94 delete factory;
95 delete fruit;
96
97 return 0;
98 }
来源：https://www.cnblogs.com/njit-sam/p/12652836.html