结构型设计模式之组合模式

  1  using System;
  2     using System.Collections;
  3 
  4     abstract class Component 
  5     {
  6         protected string strName;
  7 
  8         public Component(string name)
  9         {
 10             strName = name;
 11         }
 12 
 13         abstract public void Add(Component c);
 14     
 15         public abstract void DumpContents();
 16         
 17         // other operations for delete, get, etc.
 18     }
 19 
 20     class Composite : Component
 21     {
 22         private ArrayList ComponentList = new ArrayList();
 23         
 24         public Composite(string s) : base(s) {}
 25 
 26         override public void Add(Component c)
 27         {
 28             ComponentList.Add(c);
 29         }
 30 
 31         public override void DumpContents()
 32         {
 33             // First dump the name of this composite node
 34             Console.WriteLine("Node: {0}", strName);
 35 
 36             // Then loop through children, and get then to dump their contents
 37             foreach (Component c in ComponentList)
 38             {
 39                 c.DumpContents();
 40             }
 41         }
 42     }
 43 
 44     class Leaf : Component
 45     {
 46         public Leaf(string s) : base(s) {}
 47 
 48         override public void Add(Component c)
 49         {
 50             Console.WriteLine("Cannot add to a leaf");
 51         }
 52 
 53         public override void DumpContents()
 54         {
 55             Console.WriteLine("Node: {0}", strName);
 56         }
 57     }
 58 
 59     /// <summary>
 60     ///    Summary description for Client.
 61     /// </summary>
 62     public class Client
 63     {
 64         Component SetupTree()
 65         {
 66             // here we have to create a tree structure, 
 67             // consisting of composites and leafs.     
 68             Composite root = new Composite("root-composite");
 69             Composite parentcomposite;
 70             Composite composite;
 71             Leaf leaf;
 72 
 73             parentcomposite = root;
 74             composite = new Composite("first level - first sibling - composite");
 75             parentcomposite.Add(composite);
 76             leaf = new Leaf("first level - second sibling - leaf");
 77             parentcomposite.Add(leaf);
 78             parentcomposite = composite; 
 79             composite = new Composite("second level - first sibling - composite");
 80             parentcomposite.Add(composite);
 81             composite = new Composite("second level - second sibling - composite");
 82             parentcomposite.Add(composite);
 83 
 84             // we will leaf the second level - first sibling empty, and start 
 85             // populating the second level - second sibling 
 86             parentcomposite = composite; 
 87             leaf = new Leaf("third level - first sibling - leaf");
 88             parentcomposite.Add(leaf);
 89             
 90             leaf = new Leaf("third level - second sibling - leaf");
 91             parentcomposite.Add(leaf);
 92             composite = new Composite("third level - third sibling - composite");
 93             parentcomposite.Add(composite);
 94 
 95             return root;
 96         }
 97 
 98         public static int Main(string[] args)
 99         {   
100                Component component;
101             Client c = new Client();
102             component = c.SetupTree();
103 
104             component.DumpContents();
105             return 0;
106         }
107     }