组合模式(Composite Pattern)

介绍
将对象组合成树形结构以表示“部分-整体”的层次结构。它使得客户对单个对象和复合对象的使用具有一致性。

示例
有一个Message实体类，使其单个对象和复合对象具有一致性。

　　MessageModel

using System;

using System.Collections.Generic;

using System.Text;

namespace Pattern.Composite

{

    /// <summary>

    /// Message实体类

    /// </summary>

    public class MessageModel

    {

        /// <summary>

        /// 构造函数

        /// </summary>

        /// <param name="msg">Message内容</param>

        /// <param name="pt">Message发布时间</param>

        public MessageModel(string msg, DateTime pt)

        {

            this._message = msg;

            this._publishTime = pt;

        }

        private string _message;

        /// <summary>

        /// Message内容

        /// </summary>

        public string Message

        {

            get { return _message; }

            set { _message = value; }

        }

        private DateTime _publishTime;

        /// <summary>

        /// Message发布时间

        /// </summary>

        public DateTime PublishTime

        {

            get { return _publishTime; }

            set { _publishTime = value; }

        }

    }

}

　　MessageModelComponent

using System;

using System.Collections.Generic;

using System.Text;

namespace Pattern.Composite

{

    /// <summary>

    /// 抽象Message实体构件（Component）

    /// </summary>

    public abstract class MessageModelComponent

    {

        /// <summary>

        /// Message实体对象

        /// </summary>

        protected MessageModel _messageModel;

        /// <summary>

        /// 名称

        /// </summary>

        protected string _name;

        /// <summary>

        /// 构造函数

        /// </summary>

        /// <param name="name">名称</param>

        /// <param name="mm">Message实体对象</param>

        public MessageModelComponent(string name, MessageModel mm)

        {

            this._name = name;

            this._messageModel = mm;

        }

        /// <summary>

        /// 构造函数

        /// </summary>

        /// <param name="name">名称</param>

        public MessageModelComponent(string name)

        {

            this._name = name;

        }

        /// <summary>

        /// 添加

        /// </summary>

        /// <param name="mmc">MessageModelComponent</param>

        public abstract void Add(MessageModelComponent mmc);

        /// <summary>

        /// 删除

        /// </summary>

        /// <param name="mmc">MessageModelComponent</param>

        public abstract void Remove(MessageModelComponent mmc);

        /// <summary>

        /// 获取

        /// </summary>

        /// <param name="indent">缩进数</param>

        /// <returns></returns>

        public abstract string GetData(int indent);

    }

}

　　MessageModelLeaf

using System;

using System.Collections.Generic;

using System.Text;

namespace Pattern.Composite

{

    /// <summary>

    /// Message实体树叶（Leaf）

    /// </summary>

    public class MessageModelLeaf : MessageModelComponent

    {

        /// <summary>

        /// 构造函数

        /// </summary>

        /// <param name="name">名称</param>

        /// <param name="mm">Message实体对象</param>

        public MessageModelLeaf(string name, MessageModel mm)

            : base(name, mm)

        {

        }

        /// <summary>

        /// 添加

        /// </summary>

        /// <param name="mmc">MessageModelComponent</param>

        public override void Add(MessageModelComponent mmc)

        {

            throw new Exception("不能添加");

        }

        /// <summary>

        /// 删除

        /// </summary>

        /// <param name="mmc">MessageModelComponent</param>

        public override void Remove(MessageModelComponent mmc)

        {

            throw new Exception("不能删除");

        }

        /// <summary>

        /// 获取

        /// </summary>

        /// <param name="indent">缩进数</param>

        /// <returns></returns>

        public override string GetData(int indent)

        {

            return new String('—', indent) +

                "树叶名称：" + _name +

                "；信息内容：" + _messageModel.Message +

                "<br />";

        }

    }

}

　　MessageModelComposite

using System;

using System.Collections.Generic;

using System.Text;

namespace Pattern.Composite

{

    /// <summary>

    /// Message实体树枝（Composite）

    /// </summary>

    public class MessageModelComposite : MessageModelComponent

    {

        private List<MessageModelComponent> _list;

        /// <summary>

        /// 构造函数

        /// </summary>

        /// <param name="name">名称</param>

        public MessageModelComposite(string name)

            : base(name)

        {

            _list = new List<MessageModelComponent>();

        }

        /// <summary>

        /// 添加

        /// </summary>

        /// <param name="mmc">MessageModelComponent</param>

        public override void Add(MessageModelComponent mmc)

        {

            _list.Add(mmc);

        }

        /// <summary>

        /// 删除

        /// </summary>

        /// <param name="mmc">MessageModelComponent</param>

        public override void Remove(MessageModelComponent mmc)

        {

            _list.Remove(mmc);

        }

        /// <summary>

        /// 获取

        /// </summary>

        /// <param name="indent">缩进数</param>

        /// <returns></returns>

        public override string GetData(int indent)

        {

            string s = new String('—', indent) +

                "树枝名称：" + _name +

                "<br />";

            foreach (MessageModelComponent mmc in _list)

            {

                s += mmc.GetData(indent + 2);

            }

            return s;

        }

    }

}

　　Test

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using Pattern.Composite;

public partial class Composite : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        MessageModelComposite root = new MessageModelComposite("树枝A");

        root.Add(new MessageModelLeaf("树叶A", new MessageModel("Message内容A", DateTime.Now)));

        root.Add(new MessageModelLeaf("树叶B", new MessageModel("Message内容B", DateTime.Now)));

        MessageModelComposite comp = new MessageModelComposite("树枝B");

        comp.Add(new MessageModelLeaf("树叶C", new MessageModel("Message内容C", DateTime.Now)));

        comp.Add(new MessageModelLeaf("树叶D", new MessageModel("Message内容D", DateTime.Now)));

        root.Add(comp);

        root.Add(new MessageModelLeaf("树叶E", new MessageModel("Message内容E", DateTime.Now)));

        MessageModelLeaf l = new MessageModelLeaf("树叶F", new MessageModel("Message内容F", DateTime.Now));

        root.Add(l);

        root.Remove(l);

        Response.Write(root.GetData(1));

    }

}

　　运行结果
　　—树枝名称：树枝A
　　———树叶名称：树叶A；信息内容：Message内容A
　　———树叶名称：树叶B；信息内容：Message内容B
　　———树枝名称：树枝B
　　—————树叶名称：树叶C；信息内容：Message内容C
　　—————树叶名称：树叶D；信息内容：Message内容D
　　———树叶名称：树叶E；信息内容：Message内容E

巴特西

二十四种设计模式：组合模式(Composite Pattern)

组合模式(Composite Pattern)

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