享元模式

【1】什么是享元模式？

享元模式：

【2】享元模式的代码示例：

代码示例1：

 1 #include <iostream>

 2 #include <string>

 3 #include <map>

 4 using namespace std;

 5 

 6 class Flyweight

 7 {

 8 public:

 9     virtual void operation(int) = 0;

10 };

11 

12 class ConcreteFlyweight : public Flyweight

13 {

14     void operation(int extrinsicState)

15     {

16         cout << "具体FlyWeight: " << extrinsicState << endl;

17     }

18 };

19 

20 class UnsharedConcreteFlyweight : public Flyweight

21 {

22     void operation(int extrinsicState)

23     {

24         cout << "不共享的具体FlyWeight: " << extrinsicState << endl;        

25     }

26 };

27 

28 class FlyweightFactory

29 {

30 private:

31     map<string,Flyweight*> flyweights;

32 public:

33     FlyweightFactory()

34     {

35         flyweights["X"] = new ConcreteFlyweight();

36         flyweights["Y"] = new ConcreteFlyweight();

37         flyweights["Z"] = new UnsharedConcreteFlyweight();

38     }

39     Flyweight *getFlyweight(string key)

40     {

41         return (Flyweight *)flyweights[key];

42     }

43 };

44 

45 int main()

46 {

47     int state = 22;

48     FlyweightFactory *f = new FlyweightFactory();

49     

50     Flyweight *fx = f->getFlyweight("X");

51     fx->operation(--state);

52     

53     Flyweight *fy = f->getFlyweight("Y");

54     fy->operation(--state);

55 

56     Flyweight *fz = f->getFlyweight("Z");

57     fz->operation(--state);

58 

59     Flyweight *uf = new UnsharedConcreteFlyweight();

60     uf->operation(--state);

61 

62     return 0;

63 }

64 //Result:

65 /*

66 具体FlyWeight: 21

67 具体FlyWeight: 20

68 不共享的具体FlyWeight: 19

69 不共享的具体FlyWeight: 18

70 */

View Code

代码示例2：

 1 #include <iostream>

 2 #include <list>

 3 #include <string>

 4 #include <map>

 5 using namespace std;

 6 

 7 class WebSite

 8 {

 9 public:

10     virtual void use() = 0;

11 }; 

12 

13 class ConcreteWebSite : public WebSite

14 {

15 private:

16     string name;

17 public:

18     ConcreteWebSite(string name)

19     {

20         this->name = name;

21     }

22     void use()

23     {

24         cout << "网站分类: " << name << endl;

25     }

26 };

27 

28 class WebSiteFactory

29 {

30 private:

31     map<string,WebSite*> wf;

32 public:

33      

34     WebSite *getWebSiteCategory(string key)

35     {

36         if (wf.find(key) == wf.end())

37         {

38             wf[key] = new ConcreteWebSite(key);

39         }    

40         return wf[key];

41     }

42      

43     int getWebSiteCount()

44     {

45         return wf.size();

46     }

47 };

48 

49 int main()

50 {

51     WebSiteFactory *wf = new WebSiteFactory();

52 

53     WebSite *fx = wf->getWebSiteCategory("good");

54     fx->use();

55     

56      WebSite *fy = wf->getWebSiteCategory("产品展示");

57     fy->use();

58 

59     WebSite *fz = wf->getWebSiteCategory("产品展示");

60     fz->use();

61 

62 

63     WebSite *f1 = wf->getWebSiteCategory("博客");

64     f1->use();

65 

66     WebSite *f2 = wf->getWebSiteCategory("微博");

67     f2->use();

68 

69     cout << wf->getWebSiteCount() << endl;

70     return 0;

71 }

72 //Result:

73 /*

74 网站分类: good

75 网站分类: 产品展示

76 网站分类: 产品展示

77 网站分类: 博客

78 网站分类: 微博

79 4

80 */

View Code

 

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