享元模式(Flyweight Pattern)

介绍

运用共享技术有效地支持大量细粒度的对象。

示例

有一个Message实体类，某些对象对它的操作有Insert()和Get()方法，现在要运用共享技术支持这些对象。

　　MessageModel

using System;using System.Collections.Generic;using System.Text;namespace Pattern.Flyweight{    /// 
    /// Message实体类    /// 
    public class MessageModel    {        /// 
        /// 构造函数        /// 
        /// Message内容        /// Message发布时间        public MessageModel(string msg, DateTime pt)        {            this._message = msg;            this._publishTime = pt;        }        private string _message;        /// 
        /// Message内容        /// 
        public string Message        {            get { return _message; }            set { _message = value; }        }        private DateTime _publishTime;        /// 
        /// Message发布时间        /// 
        public DateTime PublishTime        {            get { return _publishTime; }            set { _publishTime = value; }        }    }}

　　AbstractMessage

using System;using System.Collections.Generic;using System.Text;namespace Pattern.Flyweight{    /// 
    /// 操作Message抽象类（Flyweight）    /// 
    public abstract class AbstractMessage    {        /// 
        /// 获取Message        /// 
        /// 
             public abstract List
     
       Get();        /// 
      
        /// 插入Message        /// 
        /// 
      Message实体对象        /// 
              public abstract bool Insert(MessageModel mm);    }}
     

　　SqlMessage

using System;using System.Collections.Generic;using System.Text;namespace Pattern.Flyweight{    /// 
    /// Sql方式操作Message（ConcreteFlyweight）    /// 
    public class SqlMessage : AbstractMessage    {        /// 
        /// 获取Message        /// 
        /// 
             public override List
     
       Get()        {            List
      
        l = new List
       
        ();            l.Add(new MessageModel("SQL方式获取Message", DateTime.Now));            return l;        }        /// 
        
        /// 插入Message        /// 
        /// 
        Message实体对象        /// 
                public override bool Insert(MessageModel mm)        {            // 代码略            return true;        }    }}
       
      
     

　　XmlMessage

using System;using System.Collections.Generic;using System.Text;namespace Pattern.Flyweight{    /// 
    /// Xml方式操作Message（ConcreteFlyweight）    /// 
    public class XmlMessage : AbstractMessage    {        /// 
        /// 获取Message        /// 
        /// 
             public override List
     
       Get()        {            List
      
        l = new List
       
        ();            l.Add(new MessageModel("XML方式获取Message", DateTime.Now));            return l;        }        /// 
        
        /// 插入Message        /// 
        /// 
        Message实体对象        /// 
                public override bool Insert(MessageModel mm)        {            // 代码略            return true;        }    }}
       
      
     

　　MessageFactory

using System;using System.Collections.Generic;using System.Text;namespace Pattern.Flyweight{    /// 
    /// Message工厂（FlyweightFactory）    /// 
    public class MessageFactory    {        private Dictionary
     
       _messageObjects = new Dictionary
      
       ();        /// 
       
        /// 获取Message对象        /// 
        /// 
       key        /// 
               public AbstractMessage GetMessageObject(string key)        {            AbstractMessage messageObject = null;            if (_messageObjects.ContainsKey(key))            {                messageObject = _messageObjects[key];            }            else            {                switch (key)                {                    case "xml": messageObject = new SqlMessage(); break;                    case "sql": messageObject = new XmlMessage(); break;                }                _messageObjects.Add(key, messageObject);            }            return messageObject;        }    }}
      
     

　　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.Flyweight;public partial class Flyweight : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {        string[] ary = new string[] { "xml", "sql" };        MessageFactory messageFactory = new MessageFactory();        foreach (string key in ary)        {            AbstractMessage messageObject = messageFactory.GetMessageObject(key);            Response.Write(messageObject.Insert(new MessageModel("插入", DateTime.Now)));            Response.Write("
");            Response.Write(messageObject.Get()[0].Message + " " + messageObject.Get()[0].PublishTime.ToString());            Response.Write("
");        }    }}

　　运行结果

　　True

　　SQL方式获取Message 2007-5-17 22:20:38

　　True

　　XML方式获取Message 2007-5-17 22:20:38