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

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

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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转载于:https://blog.51cto.com/webabcd/344538