说说设计模式~组合模式(Composite)

#region 组合模式
    /// <summary>
    /// 图像基类，所以和图像有关的类都继承它
    /// </summary>
    public abstract class Graphics
    {
        protected string _name;

        public Graphics(string name)
        {
            this._name = name;
        }
        public abstract void Draw();
    }
    /// <summary>
    /// 照片，它由一些简单图形组成
    /// </summary>
    public class Picture : Graphics
    {
        protected ArrayList picList = new ArrayList();

        public Picture(string name)
            : base(name)
        { }
        public override void Draw()
        {
            Console.WriteLine("Draw a" + _name.ToString());

            foreach (Graphics g in picList)
            {
                g.Draw();
            }
        }

        public void Add(Graphics g)
        {
            picList.Add(g);
        }
        public void Remove(Graphics g)
        {
            picList.Remove(g);
        }
    }
    /// <summary>
    /// 简单图形－线
    /// </summary>
    public class Line : Graphics
    {
        public Line(string name)
            : base(name)
        { }

        public override void Draw()
        {
            Console.WriteLine("Draw a" + _name.ToString());
        }
    }
    /// <summary>
    /// 简单图形－圆
    /// </summary>
    public class Circle : Graphics
    {
        public Circle(string name)
            : base(name)
        { }

        public override void Draw()
        {
            Console.WriteLine("Draw a" + _name.ToString());
        }
    }
    /// <summary>
    /// 简单图形－矩形
    /// </summary>
    public class Rectangle : Graphics
    {
        public Rectangle(string name)
            : base(name)
        { }

        public override void Draw()
        {
            Console.WriteLine("Draw a" + _name.ToString());
        }
    }

    #endregion

           #region 组合模式调用
            Picture root = new Picture("Root");

            root.Add(new Line("Line"));
            root.Add(new Circle("Circle"));

            Rectangle r = new Rectangle("Rectangle");
            root.Add(r);

            root.Draw();
            #endregion