乐在其中设计模式(C#) - 享元模式(Flyweight Pattern)

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[align=center]乐在其中设计模式(C#) - 享元模式(Flyweight Pattern)[/align]

作者：webabcd

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


{


/// <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; }


}


}


}

AbstractMessage


using System;


using System.Collections.Generic;


using System.Text;




namespace Pattern.Flyweight


{


/// <summary>


/// 操作Message抽象类（Flyweight）


/// </summary>


public abstract class AbstractMessage


{


/// <summary>


/// 获取Message


/// </summary>


/// <returns></returns>


public abstract List<MessageModel> Get();




/// <summary>


/// 插入Message


/// </summary>


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


/// <returns></returns>


public abstract bool Insert(MessageModel mm);


}


}

SqlMessage


using System;


using System.Collections.Generic;


using System.Text;




namespace Pattern.Flyweight


{


/// <summary>


/// Sql方式操作Message（ConcreteFlyweight）


/// </summary>


public class SqlMessage : AbstractMessage


{


/// <summary>


/// 获取Message


/// </summary>


/// <returns></returns>


public override List<MessageModel> Get()


{


List<MessageModel> l = new List<MessageModel>();


l.Add(new MessageModel("SQL方式获取Message", DateTime.Now));




return l;


}




/// <summary>


/// 插入Message


/// </summary>


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


/// <returns></returns>


public override bool Insert(MessageModel mm)


{


// 代码略


return true;


}


}


}

XmlMessage


using System;


using System.Collections.Generic;


using System.Text;




namespace Pattern.Flyweight


{


/// <summary>


/// Xml方式操作Message（ConcreteFlyweight）


/// </summary>


public class XmlMessage : AbstractMessage


{


/// <summary>


/// 获取Message


/// </summary>


/// <returns></returns>


public override List<MessageModel> Get()


{


List<MessageModel> l = new List<MessageModel>();


l.Add(new MessageModel("XML方式获取Message", DateTime.Now));




return l;


}




/// <summary>


/// 插入Message


/// </summary>


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


/// <returns></returns>


public override bool Insert(MessageModel mm)


{


// 代码略


return true;


}


}


}

MessageFactory


using System;


using System.Collections.Generic;


using System.Text;




namespace Pattern.Flyweight


{


/// <summary>


/// Message工厂（FlyweightFactory）


/// </summary>


public class MessageFactory


{


private Dictionary<string, AbstractMessage> _messageObjects = new Dictionary<string, AbstractMessage>();




/// <summary>


/// 获取Message对象


/// </summary>


/// <param name="key">key</param>


/// <returns></returns>


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("<br />");


Response.Write(messageObject.Get()[0].Message + " " + messageObject.Get()[0].PublishTime.ToString());


Response.Write("<br />");


}


}


}

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

参考
http://www.dofactory.com/Patterns/PatternFlyweight.aspx

OK
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