结构型设计模式——组合模式

将对象组合成树形结构以表示“部分-整体”的层次结构。Composite使得用户对单个对象和组合对象的使用方式具有一致性。

适用于

①想表示对象的部分-整体层次结构

②希望用户忽略组合对象和单个对象的不同，用户将统一地适用组合结构中的所有对象。

类图如下

 

    /// <summary>
    /// 公共组合类
    /// </summary>
    /// 实现 文件菜单目录
    internal abstract class MenuComponent
    {
        protected string Name { get; set; }
        protected int Level { get; set; }
        protected MenuComponent(string name, int level)
        {
            this.Name = name;
            this.Level = level;
        }
        /// <summary>
        /// 公共方法
        /// </summary>
        public abstract void Print();
        /// <summary>
        /// 菜单添加菜单文件方法，菜单文件调用报错
        /// </summary>
        /// <param name="component"></param>
        /// <exception cref="NotImplementedException"></exception>
        public virtual void Add(MenuComponent component)
        {
            throw new NotImplementedException();
        }
        /// <summary>
        /// 菜单删除菜单文件方法，菜单文件调用报错
        /// </summary>
        /// <param name="component"></param>
        /// <exception cref="NotImplementedException"></exception>
        public virtual void Remove(MenuComponent component)
        {
            throw new NotImplementedException();
        }

        public virtual string GetChildName()
        {
            return Name;
        }
    }

    /// <summary>
    ///菜单类，继承并且组合Compon类
    /// </summary>
    internal class Menu : MenuComponent
    {
        private List<MenuComponent> menuComponents = new List<MenuComponent>();
        public Menu(string name, int level) : base(name, level)
        {
        }

        public override void Print()
        {
            for (int i = 1; i <= Level; i++)
            {
                Console.Write("--");
            }
            Console.WriteLine(Name);
            foreach (var item in menuComponents)
            {
                item.Print();
            }
        }

        public override void Add(MenuComponent component)
        {
            menuComponents.Add(component);
        }

        public override void Remove(MenuComponent component)
        {
            menuComponents.Remove(component);
        }

        public override string GetChildName()
        {
            return base.GetChildName();
        }
    }

    /// <summary>
    /// 菜单文件类
    /// </summary>
    internal class MenuItem : MenuComponent
    {
        public MenuItem(string name, int level) : base(name, level)
        {
        }

        public override void Print()
        {
            for (int i = 1; i <= Level; i++)
            {
                Console.Write("--");
            }
            Console.WriteLine(Name);
        }
    }

    internal class Program
    {
        static void Main(string[] args)
        {
            Menu menu1 = new Menu("菜单1", 1);
            MenuItem menuItem11 = new MenuItem("菜单文件11", 2);
            menu1.Add(menuItem11);
            MenuItem menuItem12 = new MenuItem("菜单文件12", 2);
            menu1.Add(menuItem12);
            MenuItem menuItem13 = new MenuItem("菜单文件13", 2);
            menu1.Add(menuItem13);

            Menu menu2 = new Menu("菜单2", 1);
            MenuItem menuItem21 = new MenuItem("菜单21", 2);
            menu2.Add(menuItem21);
            Menu menu22 = new Menu("菜单22", 2);
            menu2.Add(menu22);
            MenuItem menuItem221 = new MenuItem("菜单文件221", 3);
            menu22.Add(menuItem221);

            Menu menu3 = new Menu("菜单3", 1);
            MenuItem menuItem31 = new MenuItem("菜单文件31", 2);
            menu3.Add(menuItem31);
            MenuItem menuItem32 = new MenuItem("菜单文件32", 2);
            menu3.Add(menuItem32);

            Menu menu = new Menu("菜单", 0);
            menu.Add(menu1);
            menu.Add(menu2);
            menu.Add(menu3);

            menu.Print();
        }
    }