C++设计模式-单件

 1 #include <iostream> 
 2 using namespace std; 
 3    
 4 //////////////////Singleton定义 
 5 /** 
 6 * @class CSingleton 
 7 * @brief 实现类把该类作为友元, 并且把构造函数作为非公有 
 8 *         如: 
 9 *          Class C 
10 *          { 
11 *          friend class CSingleton<C>; 
12 *          protected: 
13 *              C(){}; 
14 *          } 
15 */
16 template<class T> 
17 class CSingleton 
18 { 
19 public: 
20     static T* instance() 
21     { 
22         //double check. 锁前和锁后检测，保证效率和多线程正确性 
23         if (!m_pInstance) 
24         { 
25             CMutexGuard guard(m_lock);//TODO: 加锁.  
26    
27             if (!m_pInstance) 
28             { 
29                 //static T t; 
30                 //m_pInstance = &t; 
31                 m_pInstance = new T; 
32             } 
33         } 
34         return m_pInstance; 
35     }; 
36    
37 protected: 
38     CSingleton(){}; //防止产生实例 
39     CSingleton(const CSingleton&){}; //防止拷贝构造另一个实例 
40     CSingleton &operator =(const CSingleton&){}; //防止赋值构造出另一个实例 
41     virtual ~CSingleton() 
42     { 
43         if (m_pInstance) 
44         { 
45             delete m_pInstance; 
46             m_pInstance = NULL; 
47         } 
48     }; 
49    
50 private: 
51     static T* m_pInstance; //类的唯一实例 
52     //TODO: 省略了互斥锁成员m_lock 
53 }; 
54    
55    
56 //////////////////Singleton实现部分 
57 template<class T> T* CSingleton<T>::m_pInstance = NULL; 
58    
59    
60 /////////////////Singleton应用实例 
61 class CMyLog 
62 { 
63      
64 friend class CSingleton<CMyLog>; //作为友元可以访问CSingleton的保护成员 
65    
66 public: 
67     void Log(char* pszStr) 
68     { 
69         cout << "Log msg: " << pszStr << endl; 
70     } 
71    
72 private: 
73     CMyLog(){}; //不允许直接实例化 
74 }; 
75    
76 int main() 
77 { 
78     CMyLog* pLog = CSingleton<CMyLog>::instance(); 
79     pLog->Log("hello word"); 
80    
81     system("pause"); 
82     return 0; 
83 } 

1  class CBz2Helper
2  {
3   static CBz2Helper& Instance()
4   {
5    static CBz2Helper Instance;
6    return Instance;
7   }
8 
9  }