C#设计模式---组合模式（Composite Pattern）

一、目的

让客户以统一的方式处理简单对象和复杂对象。

二、定义

组合模式允许客户将对象组合成树形结构来表现”部分-整体“的层次结构，使得客户可以以一致的方式处理单个对象以及组合对象。

三、场景

假设我们要制作一个画图程序，所画的图形包括简单图形（直线，椭圆，三角形等）和复杂图形（椭圆+直线，直线+三角形等）两种。

为了能让客户已统一的方式来进行绘制简单图形和复杂图形，我们采用组合模式来实现。

四、实现

  1 using System;
  2 using System.Collections.Generic;
  3 
  4 namespace DesignMode_Composite
  5 {
  6     public abstract class Graphics
  7     {
  8         public string  Name { get; set; }
  9         public Graphics(string Name)
 10         {
 11             this.Name = Name;
 12         }
 13 
 14         public abstract void Draw();
 15         public abstract void AddGraphics(Graphics g);
 16         public abstract void RemoveGraphics(Graphics g);
 17     }
 18 
 19     /// <summary>
 20     /// Simple graphics:Line
 21     /// </summary>
 22     public class Line: Graphics
 23     {
 24         public Line(string Name):base(Name)
 25         {
 26 
 27         }
 28         public override void Draw()
 29         {
 30             Console.WriteLine("Drawing Line: " + Name);
 31         }
 32         public override void AddGraphics(Graphics g)
 33         {
 34             throw new NotImplementedException();
 35         }
 36         public override void RemoveGraphics(Graphics g)
 37         {
 38             throw new NotImplementedException();
 39         }
 40     }
 41     /// <summary>
 42     /// Simple graphics:Ellipse
 43     /// </summary>
 44     public class Ellipse:Graphics
 45     {
 46         public Ellipse(string Name):base(Name)
 47         {
 48 
 49         }
 50         public override void Draw()
 51         {
 52             Console.WriteLine("Drawing Ellipse: " + Name);
 53         }
 54         public override void AddGraphics(Graphics g)
 55         {
 56             throw new NotImplementedException();
 57         }
 58         public override void RemoveGraphics(Graphics g)
 59         {
 60             throw new NotImplementedException();
 61         }
 62 
 63     }
 64     /// <summary>
 65     /// Simple graphics:Rectangle
 66     /// </summary>
 67     public class Rectangle:Graphics
 68     {
 69         public Rectangle(string Name):base(Name)
 70         {
 71 
 72         }
 73         public override void Draw()
 74         {
 75             Console.WriteLine("Drawing Rectangle: " +Name);
 76         }
 77         public override void AddGraphics(Graphics g)
 78         {
 79             throw new NotImplementedException();
 80         }
 81         public override void RemoveGraphics(Graphics g)
 82         {
 83             throw new NotImplementedException();
 84         }
 85     }
 86     /// <summary>
 87     /// Complex graphics
 88     /// </summary>
 89     public class ComplexGraphics:Graphics
 90     {
 91         private List<Graphics> graphicsList;
 92         public ComplexGraphics(string Name):base(Name)
 93         {
 94             graphicsList = new List<Graphics>();
 95         }
 96         public override void Draw()
 97         {
 98 
 99             Console.ForegroundColor = (ConsoleColor)Math.Abs(new Random().Next(15));
100             Console.WriteLine("Drawing Complex: " + Name);
101             Console.ResetColor();
102             foreach (var g in graphicsList)
103             {
104                 g.Draw();
105             }
106       
107         }
108         public override void AddGraphics(Graphics g)
109         {
110             graphicsList.Add(g);
111         }
112         public override void RemoveGraphics(Graphics g)
113         {
114             graphicsList.Remove(g);
115         }
116     }
117     class Program
118     {
119         static void Main(string[] args)
120         {
121 
122             Console.ForegroundColor = ConsoleColor.DarkGreen;
123             Console.WriteLine("**********Welcome to use drawing tool**********");
124             Console.ResetColor();
125 
126             List<Graphics> graphicsList = new List<Graphics>();
127             Graphics smpGraphicsLineA = new Line("Line A");//Create a simple line A
128             Graphics smpGraphicsLineB = new Line("Line B");//Create a simple line B
129             Graphics smpGraphicsEllipse = new Ellipse("Ellipse A");
130             Graphics smpGraphicsRectangle = new Rectangle("Rectangle A");
131 
132             Graphics comGraphicsA = new ComplexGraphics("Complex A");
133             comGraphicsA.AddGraphics(smpGraphicsLineA);
134             comGraphicsA.AddGraphics(smpGraphicsEllipse);
135 
136             Graphics comGraphicsB = new ComplexGraphics("Complex B");
137             comGraphicsB.AddGraphics(smpGraphicsLineB);
138             comGraphicsB.AddGraphics(smpGraphicsRectangle);
139 
140             graphicsList.Add(smpGraphicsLineA);
141             graphicsList.Add(smpGraphicsLineB);
142             graphicsList.Add(smpGraphicsEllipse);
143             graphicsList.Add(smpGraphicsRectangle);
144             graphicsList.Add(comGraphicsA);
145             graphicsList.Add(comGraphicsB);
146 
147             foreach(var g in graphicsList)
148             {
149                 g.Draw();
150             }
151 
152         }
153     }
154 }

View Code

运行结果如下：

五、类图

六、描述

组合模式中，涉及以下三个元素：

（1）抽象组件（Component）角色：这是一个抽象角色，上面的类Graphics充当这个角色，它定义了Leaf和Composite公共的接口，可以用来管理所有的子对象。

（2）树叶组件（Leaf）角色：树叶对象没有子级对象，上面实现中类Line和Ellipse和Rectangle充当这个角色。

（3）树枝组件（Composite）角色：树枝组件有子级对象，上面实现的ComplexGraphics充当这个角色，树枝对象给出所有管理子对象的方法实现，如AddGraphics、RemoveGraphics。

posted on 2018-09-07 13:48 缘惜阅读(259) 评论(0) 收藏举报