创建型设计模式之工厂模式

结构

  1 using System;
  2
  3     // These classes could be part of a framework,
  4     // which we will call DP
  5     // ===========================================
  6
  7     abstract class DPDocument
  8     {
  9         abstract public void Dump();
 10     }
 11
 12     abstract class DPWorkspace
 13     {
 14         abstract public void Dump();
 15     }
 16
 17     abstract class DPView
 18     {
 19         abstract public void Dump();
 20     }
 21
 22     abstract class DPFactory
 23     {
 24         abstract public DPDocument CreateDocument();
 25         abstract public DPView CreateView();
 26         abstract public DPWorkspace CreateWorkspace();
 27     }
 28
 29     abstract class DPApplication
 30     {
 31         protected DPDocument doc;
 32         protected DPWorkspace workspace;
 33         protected DPView view;
 34
 35         public void ConstructObjects(DPFactory factory)
 36         {
 37             // Create objects as needed
 38             doc = factory.CreateDocument();
 39             workspace = factory.CreateWorkspace();
 40             view = factory.CreateView();
 41         }
 42
 43         abstract public void Dump();
 44
 45         public void DumpState()
 46         {
 47             if (doc != null) doc.Dump();
 48             if (workspace != null) workspace.Dump();
 49             if (view != null) view.Dump();
 50         }
 51     }
 52
 53     // These classes could be part of an application
 54     class MyApplication : DPApplication
 55     {
 56         MyFactory myFactory = new MyFactory();
 57
 58         override public void Dump()
 59         {
 60             Console.WriteLine("MyApplication exists");
 61         }
 62
 63         public void CreateFamily()
 64         {
 65             MyFactory myFactory = new MyFactory();
 66             ConstructObjects(myFactory);
 67         }
 68     }
 69
 70     class MyDocument : DPDocument
 71     {
 72         public MyDocument()
 73         {
 74                 Console.WriteLine("in MyDocument constructor");
 75         }
 76
 77         override public void Dump()
 78         {
 79             Console.WriteLine("MyDocument exists");
 80         }
 81     }
 82
 83     class MyWorkspace : DPWorkspace
 84     {
 85         override public void Dump()
 86         {
 87             Console.WriteLine("MyWorkspace exists");
 88         }
 89     }
 90
 91     class MyView : DPView
 92     {
 93         override public void Dump()
 94         {
 95             Console.WriteLine("MyView exists");
 96         }
 97     }
 98
 99     class MyFactory : DPFactory
100     {
101         override public DPDocument CreateDocument()
102         {
103             return new MyDocument();
104         }
105         override public DPWorkspace CreateWorkspace()
106         {
107             return new MyWorkspace();
108         }
109         override public DPView CreateView()
110         {
111             return new MyView();
112         }
113     }
114
115     /// <summary>
116     ///    Summary description for Client.
117     /// </summary>
118     public class Client
119     {
120         public static int Main(string[] args)
121         {
122             MyApplication myApplication = new MyApplication();
123
124             myApplication.CreateFamily();
125
126             myApplication.DumpState();
127
128             return 0;
129         }
130     }

工厂模式