Singleton 

  1 //Singleton.h
  2 
  3  
  4 
  5 #ifndef _SINGLETON_H_
  6 
  7 #define _SINGLETON_H_
  8 
  9  
 10 
 11 #include <iostream>
 12 
 13 using namespace std;
 14 
 15  
 16 
 17 class Singleton
 18 
 19 {
 20 
 21 public:
 22 
 23        static Singleton* Instance();
 24 
 25  
 26 
 27        virtual void PrintInfo();
 28 
 29  
 30 
 31 protected:
 32 
 33        Singleton();
 34 
 35  
 36 
 37 private:
 38 
 39        static Singleton* _instance;
 40 
 41  
 42 
 43 };
 44 
 45  
 46 
 47 class SingletonDeriveA:public Singleton
 48 
 49 {
 50 
 51 private:
 52 
 53        friend class Singleton;
 54 
 55        SingletonDeriveA();
 56 
 57 public:
 58 
 59        virtual ~SingletonDeriveA();
 60 
 61  
 62 
 63        void PrintInfo();
 64 
 65       
 66 
 67 };
 68 
 69  
 70 
 71 class SingletonDeriveB:public Singleton
 72 
 73 {
 74 
 75 private:
 76 
 77        friend class Singleton;
 78 
 79        SingletonDeriveB();
 80 
 81  
 82 
 83 public:
 84 
 85        virtual ~SingletonDeriveB();
 86 
 87  
 88 
 89        void PrintInfo();
 90 
 91       
 92 
 93 };
 94 
 95  
 96 
 97 char* GetSingletionType();
 98 
 99  
100 
101 #endif //~_SINGLETON_H_
102 
103 //Singleton.cpp
104 
105  
106 
107 #include "Singleton.h"
108 
109  
110 
111 #include <ctime>  //for time
112 
113  
114 
115 #include <iostream>
116 
117 using namespace std;
118 
119  
120 
121 Singleton* Singleton::_instance = 0;
122 
123  
124 
125 Singleton::Singleton()
126 
127 {
128 
129        cout<<"Singleton...."<<endl;
130 
131 }
132 
133  
134 
135 Singleton* Singleton::Instance()
136 
137 {
138 
139        const char* type = GetSingletionType();
140 
141  
142 
143        if (_instance == 0)
144 
145        {
146 
147               if (strcmp(type,"SingletonDeriveA") == 0)
148 
149               {
150 
151                      _instance = new SingletonDeriveA();
152 
153               }
154 
155               else if (strcmp(type,"SingletonDeriveB") == 0)
156 
157               {
158 
159                      _instance = new SingletonDeriveB();
160 
161               }
162 
163               else
164 
165               {
166 
167                      _instance = new Singleton();
168 
169               }
170 
171        }
172 
173  
174 
175        return _instance;
176 
177 }
178 
179  
180 
181 void Singleton::PrintInfo()
182 
183 {
184 
185        cout<<"Singleton type:Singleton"<<endl;
186 
187 }
188 
189  
190 
191 SingletonDeriveA::SingletonDeriveA()
192 
193 {
194 
195        cout<<"SingletonDeriveA...."<<endl;
196 
197 }
198 
199  
200 
201 SingletonDeriveA::~SingletonDeriveA()
202 
203 {
204 
205  
206 
207 }
208 
209  
210 
211 void SingletonDeriveA::PrintInfo()
212 
213 {
214 
215        cout<<"Singleton type:SingletonDeriveA"<<endl;
216 
217 }
218 
219  
220 
221 SingletonDeriveB::SingletonDeriveB()
222 
223 {
224 
225        cout<<"SingletonDeriveB...."<<endl;
226 
227 }
228 
229  
230 
231 SingletonDeriveB::~SingletonDeriveB()
232 
233 {
234 
235  
236 
237 }
238 
239  
240 
241 void SingletonDeriveB::PrintInfo()
242 
243 {
244 
245        cout<<"Singleton type:SingletonDeriveB"<<endl;
246 
247 }
248 
249  
250 
251  
252 
253 char* GetSingletionType()
254 
255 {
256 
257        //随机返回一个Singleton子类
258 
259        srand((unsigned int)time(NULL));
260 
261        int SINGLETON_TYPE = rand() % 3;
262 
263  
264 
265        switch (SINGLETON_TYPE)
266 
267        {
268 
269        case 0:
270 
271               return "SingletonDeriveA";
272 
273               break;
274 
275        case 1:
276 
277               return "SingletonDeriveB";
278 
279               break;
280 
281        case 2:
282 
283               return "Singleton";
284 
285               break;
286 
287        default :
288 
289               return "Singleton";
290 
291               break;
292 
293        }
294 
295 }



posted @ 2012-02-02 11:38  linyliny  阅读(168)  评论(0)    收藏  举报