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 程式師世界 >> 編程語言 >> .NET網頁編程 >> C# >> 關於C# >> 設計模式(C#) - 享元模式(Flyweight Pattern)

設計模式(C#) - 享元模式(Flyweight Pattern)

編輯:關於C#

返回“設計模式(C#)系列文章索引”

介紹

運用共享技術有效地支持大量細粒度的對象。

示例

有一個Message實體類,某些對象對它的操作有Insert()和Get()方法,現在要運用共享技術支持這些對象。

MessageModel

using System;
using System.Collections.Generic;
using System.Text;

namespace Pattern.Flyweight
{
  /**//// <summary>
  /// Message實體類
  /// </summary>
  public class MessageModel
  {
    /**//// <summary>
    /// 構造函數
    /// </summary>
    /// <param name="msg">Message內容</param>
    /// <param name="pt">Message發布時間</param>
    public MessageModel(string msg, DateTime pt)
    {
      this._message = msg;
      this._publishTime = pt;
    }

    private string _message;
    /**//// <summary>
    /// Message內容
    /// </summary>
    public string Message
    {
      get { return _message; }
      set { _message = value; }
    }

    private DateTime _publishTime;
    /**//// <summary>
    /// Message發布時間
    /// </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抽象類(Flyweight)
  /// </summary>
  public abstract class AbstractMessage
  {
    /**//// <summary>
    /// 獲取Message
    /// </summary>
    /// <returns></returns>
    public abstract List<MessageModel> Get();

    /**//// <summary>
    /// 插入Message
    /// </summary>
    /// <param name="mm">Message實體對象</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>
    /// 獲取Message
    /// </summary>
    /// <returns></returns>
    public override List<MessageModel> Get()
    {
      List<MessageModel> l = new List<MessageModel>();
      l.Add(new MessageModel("SQL方式獲取Message", DateTime.Now));

      return l;
    }

    /**//// <summary>
    /// 插入Message
    /// </summary>
    /// <param name="mm">Message實體對象</param>
    /// <returns></returns>
    public override bool Insert(MessageModel mm)
    {
      // 代碼略
      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>
    /// 獲取Message
    /// </summary>
    /// <returns></returns>
    public override List<MessageModel> Get()
    {
      List<MessageModel> l = new List<MessageModel>();
      l.Add(new MessageModel("XML方式獲取Message", DateTime.Now));

      return l;
    }

    /**//// <summary>
    /// 插入Message
    /// </summary>
    /// <param name="mm">Message實體對象</param>
    /// <returns></returns>
    public override bool Insert(MessageModel mm)
    {
      // 代碼略
      return true;
    }
  }
}

MessageFactory

using System;
using System.Collections.Generic;
using System.Text;

namespace Pattern.Flyweight
{
  /**//// <summary>
  /// Message工廠(FlyweightFactory)
  /// </summary>
  public class MessageFactory
  {
    private Dictionary<string, AbstractMessage> _messageObjects = new Dictionary<string, AbstractMessage>();

    /**//// <summary>
    /// 獲取Message對象
    /// </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 />");
    }
  }
}

運行結果

True

SQL方式獲取Message 2007-5-17 22:20:38

True

XML方式獲取Message 2007-5-17 22:20:38

參考

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

OK

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