C++模式学习------代理模式

Proxy代理模式：

为其他对象提供一种代理以控制对这个对象的访问。代理类作为桥梁是请求方和执行方的中间者，将请求方和真正的执行方分割开来，也是两者之间调用的协调者。例如执行类也就是被代理类，可以在不考虑各种特殊条件下提供所有的执行方法，请求者也可以不考虑特殊条件提出所有的请求。而在调用和被调用时需要考虑的所有条件，在代理类中完成。

1. 考虑请求方的情况：由各代理处理不同的请求

 1 class Service
 2 {
 3 public:
 4     Service();
 5 
 6     virtual void serviceLv0() = 0;
 7     virtual void serviceLv1() = 0;
 8     virtual void serviceLv2() = 0;
 9 };
10 
11 class OfferService : public Service
12         //真正的服务提供者
13 {
14 public:
15     OfferService();
16 
17     void serviceLv0()
18     {
19         cout<<"Offer serviceLv0"<<endl;
20     }
21     void serviceLv1()
22     {
23         cout<<"Offer serviceLv0"<<endl;
24     }
25     void serviceLv2()
26     {
27         cout<<"Offer serviceLv0"<<endl;
28     }
29 };
30 
31 class ProxyOfferServiceLv0 : public Service
32         //lv0 的服务提供代理
33 {
34 public:
35     ProxyOfferServiceLv0()
36     {
37         m_instance = new OfferService();
38     }
39 
40     void serviceLv0()
41     {
42         m_instance->serviceLv0();
43     }
44     void serviceLv1()
45     {
46         cout<<"No serviceLv0"<<endl;
47     }
48     void serviceLv2()
49     {
50         cout<<"No serviceLv0"<<endl;
51     }
52 
53     OfferService* m_instance;
54 };
55 
56 class ProxyOfferServiceLv2 : public Service
57         //lv2 的服务提供代理
58 {
59 public:
60     ProxyOfferServiceLv2()
61     {
62         m_instance = new OfferService();
63     }
64 
65     void serviceLv0()
66     {
67         m_instance->serviceLv0();
68     }
69     void serviceLv1()
70     {
71         m_instance->serviceLv1();
72     }
73     void serviceLv2()
74     {
75         m_instance->serviceLv2();
76     }
77 
78     OfferService* m_instance;
79 };

2. 考虑执行方的情况

  1 enum EnumState
  2 {
  3     State_isOK,
  4     State_notOK
  5 };
  6 
  7 class Service
  8 {
  9 public:
 10     Service();
 11 
 12     virtual void serviceLv0() = 0;
 13     virtual void serviceLv1() = 0;
 14     virtual void serviceLv2() = 0;
 15 
 16     int getServiceState()
 17     {
 18         return m_state;
 19     }
 20 
 21     int m_state; // EnumState
 22 };
 23 
 24 class OfferService : public Service
 25         //真正的服务提供者
 26 {
 27 public:
 28     OfferService();
 29 
 30     void serviceLv0()
 31     {
 32         cout<<"Offer serviceLv0"<<endl;
 33     }
 34     void serviceLv1()
 35     {
 36         cout<<"Offer serviceLv0"<<endl;
 37     }
 38     void serviceLv2()
 39     {
 40         cout<<"Offer serviceLv0"<<endl;
 41     }
 42 };
 43 
 44 class ProxyOfferServiceLv0 : public Service
 45         //lv0 的服务提供代理
 46 {
 47 public:
 48     ProxyOfferServiceLv0()
 49     {
 50         m_instance = new OfferService();
 51     }
 52 
 53     void serviceLv0()
 54     {
 55         if(m_instance->getServiceState() == State_isOK)
 56             //查看执行方的状态
 57         {
 58             m_instance->serviceLv0();
 59         }
 60         else
 61         {
 62             cout<<"serviceLv0 is noOK"<<endl;
 63         }
 64     }
 65     void serviceLv1()
 66     {
 67         cout<<"No serviceLv0"<<endl;
 68     }
 69     void serviceLv2()
 70     {
 71         cout<<"No serviceLv0"<<endl;
 72     }
 73 
 74     OfferService* m_instance;
 75 };
 76 
 77 class ProxyOfferServiceLv2 : public Service
 78         //lv2 的服务提供代理
 79 {
 80 public:
 81     ProxyOfferServiceLv2()
 82     {
 83         m_instance = new OfferService();
 84     }
 85 
 86     void serviceLv0()
 87     {
 88         if(m_instance->getServiceState() == State_isOK)
 89             //查看执行方的状态
 90         {
 91             m_instance->serviceLv0();
 92         }
 93         else
 94         {
 95             cout<<"serviceLv0 is noOK"<<endl;
 96         }
 97     }
 98     void serviceLv1()
 99     {
100         if(m_instance->getServiceState() == State_isOK)
101             //查看执行方的状态
102         {
103             m_instance->serviceLv1();
104         }
105         else
106         {
107             cout<<"serviceLv1 is noOK"<<endl;
108         }
109     }
110     void serviceLv2()
111     {
112         if(m_instance->getServiceState() == State_isOK)
113             //查看执行方的状态
114         {
115             m_instance->serviceLv2();
116         }
117         else
118         {
119             cout<<"serviceLv2 is noOK"<<endl;
120         }
121     }
122 
123     OfferService* m_instance;
124 };