设计模式(1)单例模式

程序中有时候需要保存全局的数据,比如程序的配置文件,需要随时检索的.比如程序中有些变量需要全局保存全局用,这时候我们不想用一个全局变量来保存

这时候,可以使用单例模式,从名称可以看出,单例模式就是类的实例全局只创建一个.怎么样才能保存只创建一个实例呢?

我们可以设置标识位,创建过的就不再创建了.下面是单例的简单实现

 

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template<class T>   class Singleton   {   public:       static T* GetInstance()       {           static Mutex mutex;           if(!ms_instance)           {               Locker locker(mutex);               if (!ms_instance)               {                   ms_instance = new T;               }           }             return ms_instance;       }         static void SetInstance(T* pInst)       {           ms_instance = pInst;       }         static void DeleteInstance()       {           if (ms_instance)           {               delete ms_instance;               ms_instance = NULL;           }       }   private:       class Garbo       {       public:           ~Garbo()           {               if( Singleton::ms_instance )               {                     delete ms_instance;                   ms_instance = NULL;               }           }       };       static Garbo garbo;   protected:       Singleton() {}       ~Singleton() {}         Singleton(const Singleton&) {}       Singleton& operator=(const Singleton&) {}     private:       static T*           ms_instance;     };     template<class T>   T* Singleton<T>::ms_instance = 0;

　　

 

用法:

class Test : public Singleton<Test>

{

//your code

}

 

Test::GetInstance()->your method