设计模式之美：Proxy（代理）

 1 namespace ProxyPattern.Implementation1
 2 {
 3   public abstract class Subject
 4   {
 5     public abstract string Name { get; }
 6     public abstract void Request();
 7   }
 8 
 9   public class ConcreteSubject : Subject
10   {
11     private string _name;
12 
13     public ConcreteSubject(string name)
14     {
15       _name = name;
16     }
17 
18     public override string Name { get { return _name; } }
19 
20     public override void Request()
21     {
22       // do something
23     }
24   }
25 
26   public class Proxy : Subject
27   {
28     private Subject _realSubject = null;
29     private string _name;
30 
31     public Proxy(string name)
32     {
33       _name = name;
34     }
35 
36     public override string Name { get { return _name; } }
37 
38     public override void Request()
39     {
40       if (_realSubject == null)
41         LoadRealSubject();
42 
43       _realSubject.Request();
44     }
45 
46     private void LoadRealSubject()
47     {
48       // do some heavy things
49       _realSubject = new ConcreteSubject(_name);
50     }
51   }
52 
53   public class Client
54   {
55     public void TestCase1()
56     {
57       Subject subject = new Proxy("SubjectName");
58       var subjectName = subject.Name;
59       subject.Request();
60     }
61   }
62 }