abstract  class Component   //抽象的部件类描述将来所有部件共有的行为
    {
        protected string name;//名称

        public Component(string name)
        {
            this.name = name;
        }

        public abstract void Add(Component c);//添加子部件
        public abstract void Remove(Component c);//删除子部件
        public abstract void Display(int depth);//展示部件结构
    }
     //组合部件类
    class Leaf : Component
    {
        public Leaf(string name) : base(name) { }
       //叶子节点不具备添加部件的功能，所以不实现
        public override void Add(Component c)
        {
            Console.WriteLine("Cannot add to a leaf"); 
        }

        //同上
        public override void Remove(Component c)
        {
            Console.WriteLine("Cannot remove from a leaf"); 
        }

        //显示出自身的执行结果
        public override void Display(int depth)
        {
            Console .WriteLine (new String ('-',depth )+name );
        }
    }
    
    //组合类
    class Composite : Component
    {
        //用来保存组合的部件
        private List<Component> children = new List<Component>();
        
        
        public Composite(string name) : base(name) { }

        //添加节点
        public override void Add(Component c)
        {
            children.Add(c);
        }

        //删除部件
        public override void Remove(Component c)
        {
            children.Remove(c);
        }

        //遍历子节点并展示
        public override void Display(int depth)
        {
            Console.WriteLine(new string('-', depth) + name);
            foreach (Component component in children)
            {
                component.Display(depth + 2);
            }
        }
    }

客户端代码

static void Main(string[] args)
        {
            //构造根节点
            Composite root = new Composite("root");
           
            //添加叶子节点
            root.Add(new Leaf("Leaf A"));
            root.Add(new Leaf("Leaf B"));

            //构建组合
            Composite comp = new Composite("Composite X");
            
            //为组合添加叶子节点
            comp.Add(new Leaf("Leaf XA"));
            comp.Add(new Leaf("Leaf XB"));

            root.Add(comp);
            //同comp
            Composite comp2 = new Composite("Composite XY");
            comp2.Add(new Leaf("Leaf XYA"));
            comp2.Add(new Leaf("Leaf XYB"));

            root.Add(comp2);
            //添加叶子节点
            root.Add(new Leaf("Leaf C"));
            
            Leaf leaf= new Leaf("Leaf D");

            root.Add(leaf);
            root.Remove(leaf);
            //展示结果
            root.Display(1);

            Console.Read();

        }

适用情况

特点