相信大家對Observer模式都比較了解，在開發過程中這個模式經常被使用。
下面，和大家分享下我的實現，我就直接貼代碼了，希望對閱讀過的朋友有幫助。
個人認為，其中的模板類比較重要，具有一定的復用性。如模板類中的函數不滿足要求，就修改、添加吧。
1 /**
2 CopyRight: (C) 2011 by caipan
3 Email: caipan0206@163.com
4 */
5 #include <iostream>
6 #include <list>
7 class ICalcEventSource;
8
9 template <class _Listener>
10 class EventSourceMulticaster
11 {
12 public:
13 ~EventSourceMulticaster()
14 {
15 m_listeners.clear();
16 }
17
18 bool addListenerInternal(_Listener* pListener)
19 {
20 for (typename std::list<_Listener *>::iterator i = m_listeners.begin(); i != m_listeners.end(); i++)
21 {
22 if (*i == pListener)
23 {
24 return false;
25 }
26 }
27
28 m_listeners.push_back(pListener);
29
30 return true;
31 }
32
33 bool removeListenerInternal(_Listener* pListener)
34 {
35 if (pListener == NULL)
36 {
37 return false;
38 }
39
40 for (typename std::list<_Listener *>::iterator i = m_listeners.begin(); i != m_listeners.end(); i++)
41 {
42 if (*i == pListener)
43 {
44 m_listeners.erase(i);
45 return true;
46 }
47 }
48
49 return false;
50 }
51
52 void sendEvent(void (_Listener::*func)())
53 {
54 typename std::list<_Listener *>::iterator iter = m_listeners.begin();
55 while (iter != m_listeners.end())
56 {
57 _Listener *pListener = *iter;
58 ++iter;
59 (pListener->*func)();
60 }
61 }
62
63 template <class _A1>
64 void sendEvent1(void (_Listener::*func)(_A1), _A1 a1)
65 {
66 typename std::list<_Listener *>::iterator iter = m_listeners.begin();
67 while (iter != m_listeners.end())
68 {
69 _Listener *pListener = *iter;
70 ++iter;
71 (pListener->*func)(a1);
72 }
73 }
74
75 template <class _A1, class _A2>
76 void sendEvent2(void (_Listener::*func)(_A1, _A2), _A1 a1, _A2 a2)
77 {
78 typename std::list<_Listener *>::iterator iter = m_listeners.begin();
79 while (iter != m_listeners.end())
80 {
81 _Listener *pListener = *iter;
82 ++iter;
83 (pListener->*func)(a1, a2);
84 }
85 }
86
87 private:
88 std::list<_Listener *> m_listeners;
89 };
90
91 class ICalcEventListener
92 {
93 public:
94 virtual void onCalcBegin(ICalcEventSource *pSender) = 0;
95 };
96
97 class ICalcEventSource
98 {
99 public:
100 virtual bool addListener(ICalcEventListener *pListener) = 0;
101 virtual bool removeListener(ICalcEventListener *pListener) = 0;
102 };
103
104 class CMyPrivateCalcView_1 : ICalcEventListener
105 {
106 public:
107 virtual void onCalcBegin(ICalcEventSource *pSender)
108 {
109 cout<<"CMyPrivateCalcView_1 receive CalcBegin message"<<endl;
110 }
111
112 void init(ICalcEventSource *pSource)
113 {
114 pSource->addListener(this);
115 }
116 };
117
118 class CMyPrivateCalcView_2 : ICalcEventListener
119 {
120 public:
121 virtual void onCalcBegin(ICalcEventSource *pSender)
122 {
123 cout<<"CMyPrivateCalcView_2 receive CalcBegin message"<<endl;
124 }
125
126 void init(ICalcEventSource *pSource)
127 {
128 pSource->addListener(this);
129 }
130 };
131
132 class CMyPrivateCalc : public ICalcEventSource
133 , public EventSourceMulticaster<ICalcEventListener>
134 {
135 public:
136 virtual bool addListener(ICalcEventListener *pListener)
137 {
138 return addListenerInternal(pListener);
139 }
140
141 virtual bool removeListener(ICalcEventListener *pListener)
142 {
143 return removeListenerInternal(pListener);
144 }
145
146 void calcBegin()
147 {
148 sendEvent1(&ICalcEventListener::onCalcBegin, static_cast<ICalcEventSource*>(this));
149 }
150 };
151 //////////////////////////////////////////////////////////////////////////
152 int _tmain(int argc, _TCHAR* argv[])
153 {
154 CMyPrivateCalc *pCalc = new CMyPrivateCalc;
155 CMyPrivateCalcView_1 *pView_1 = new CMyPrivateCalcView_1;
156 pView_1->init(pCalc);
157 CMyPrivateCalcView_2 *pView_2 = new CMyPrivateCalcView_2;
158 pView_2->init(pCalc);
159
160 pCalc->calcBegin();
161 }