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
{
/// <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