组合模式【大话设计模式DEMO】

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。组合模式使得用户对单个对象和组合对象的使用具有一致性。
整体与部分可以被一致对待。（看上去也有递归的感觉）

类设计图：

DEMO代码：

 class RunCompositePattern
    {
     
        static void Main(string[] args)
        {
            Composite root = new Composite("root");
            root.Add(new Leaf("A"));
            root.Add(new Leaf("B"));

            Composite comp = new Composite("Compostie X");
            comp.Add(new Leaf("Leaf XA"));
            comp.Add(new Leaf("Leaf XB"));

            root.Add(comp);

            Composite comp2 = new Composite("Compostie XY");
            comp2.Add(new Leaf("Leaf XYA"));
            comp2.Add(new Leaf("Leaf XYB"));

            comp.Add(comp2);

            root.Add(new Leaf("C"));
            Leaf leaf = new Leaf("D");
            root.Add(leaf);
            root.Remove(leaf);
            root.Display(1);
            Console.ReadKey();

        }
    }

    abstract class Component
    {
        protected string Name;
        public Component(string name)
        {
            this.Name = name;
        }
        public abstract void Add(Component c);
        public abstract void Remove(Component c);
        public abstract void Display(int depth);
    }

    class Leaf : Component
    {
        public Leaf(string name)
            : base(name)
        {

        }
        public override void Add(Component c)
        {
            Console.WriteLine("不能为叶子节点添加子元素");
        }

        public override void Remove(Component c)
        {
            Console.WriteLine("不能从叶子节点删除子元素");
        }
        public override void Display(int depth)
        {
            Console.WriteLine(new String('-', depth) + Name);
        }
    }

    class Composite : Component
    {
        private List<Component> children = new List<Component>();
        public Composite(string name)
            : base(name)
        { }
        public override void Add(Component c)
        {
            children.Add(c);
        }
        public override void Remove(Component c)
        {
            children.Remove(c);
        }
        public override void Display(int depth)
        {
            Console.WriteLine(new String('-', depth) + Name);
            foreach (Component item in children)
            {
                item.Display(depth + 2);
            }
        }
    }

运行结果：