10.组合模式(Composite Pattern)

using System;

using System.Collections.Generic;



namespace ConsoleApplication8

{

    class Program

    {

        static void Main(string[] args)

        {

            ComplexGraphics complexGraphics = new ComplexGraphics("一个复杂图形和两条线段组成的复杂图形");

            complexGraphics.Add(new Line("线段A"));

            ComplexGraphics CompositeCG = new ComplexGraphics("一个圆和一条线组成的复杂图形");

            CompositeCG.Add(new Circle("圆"));

            CompositeCG.Add(new Circle("线段B"));

            complexGraphics.Add(CompositeCG);

            Line l = new Line("线段C");

            complexGraphics.Add(l);



            // 显示复杂图形的画法

            Console.WriteLine("复杂图形的绘制如下：");

            Console.WriteLine("---------------------");

            complexGraphics.Draw();

            Console.WriteLine("复杂图形绘制完成");

            Console.WriteLine("---------------------");

            Console.WriteLine();



            // 移除一个组件再显示复杂图形的画法

            complexGraphics.Remove(l);

            Console.WriteLine("移除线段C后，复杂图形的绘制如下：");

            Console.WriteLine("---------------------");

            complexGraphics.Draw();

            Console.WriteLine("复杂图形绘制完成");

            Console.WriteLine("---------------------");

            Console.Read();

        }

    }



    /// <summary>

    /// 图形抽象类

    /// </summary>

    public abstract class Graphics

    {

        public string Name { get; set; }

        public Graphics(string name)

        {

            this.Name = name;

        }



        public abstract void Draw();

        public abstract void Add(Graphics g);

        public abstract void Remove(Graphics g);

    }



    /// <summary>

    /// 简单图形类——线

    /// </summary>

    public class Line : Graphics

    {

        public Line(string name)

            : base(name)

        { }



        // 重写父类抽象方法

        public override void Draw()

        {

            Console.WriteLine("画  " + Name);

        }



        // 因为简单图形在添加或移除其他图形，所以简单图形Add或Remove方法没有任何意义

        // 如果客户端调用了简单图形的Add或Remove方法将会在运行时抛出异常

        // 我们可以在客户端捕获该类移除并处理

        public override void Add(Graphics g)

        {

            throw new Exception("不能向简单图形Line添加其他图形");

        }

        public override void Remove(Graphics g)

        {

            throw new Exception("不能向简单图形Line移除其他图形");

        }

    }



    /// <summary>

    /// 简单图形类——圆

    /// </summary>

    public class Circle : Graphics

    {

        public Circle(string name)

            : base(name)

        { }





        // 重写父类抽象方法

        public override void Draw()

        {

            Console.WriteLine("画  " + Name);

        }



        public override void Add(Graphics g)

        {

            throw new Exception("不能向简单图形Circle添加其他图形");

        }



        public override void Remove(Graphics g)

        {

            throw new Exception("不能向简单图形Circle移除其他图形");

        }

    }



    /// <summary>

    /// 复杂图形，由一些简单图形组成,这里假设该复杂图形由一个圆两条线组成的复杂图形

    /// </summary>

    public class ComplexGraphics : Graphics

    {

        private List<Graphics> complexGraphicsList = new List<Graphics>();



        public ComplexGraphics(string name)

            : base(name)

        { }



        /// <summary>

        /// 复杂图形的画法

        /// </summary>

        public override void Draw()

        {

            foreach (Graphics g in complexGraphicsList)

            {

                g.Draw();

            }

        }



        public override void Add(Graphics g)

        {

            complexGraphicsList.Add(g);

        }



        public override void Remove(Graphics g)

        {

            complexGraphicsList.Remove(g);

        }

    }

}