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介紹
定義一個用於創建對象的接口,讓子類決定將哪一個類實例化。Factory Method使一個類的實例化延遲到其子類。
示例
有SqlMessage和XmlMessage,用Factory Method來實例化它們。
MessageModel
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.FactoryMethod
{
/**//// <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.FactoryMethod
{
/**//// <summary>
/// 操作Message抽象類(Product)
/// </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.FactoryMethod
{
/**//// <summary>
/// Sql方式操作Message(ConcreteProduct)
/// </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.FactoryMethod
{
/**//// <summary>
/// Xml方式操作Message(ConcreteProduct)
/// </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;
}
}
}
AbstractMessageFactory
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.FactoryMethod
{
/**//// <summary>
/// 抽象Message工廠(Creator)
/// </summary>
public abstract class AbstractMessageFactory
{
// An Operation
/**//// <summary>
/// 工廠方法
/// </summary>
/// <returns>AbstractMessage</returns>
public abstract AbstractMessage CreateMessage();
}
}
SqlMessageFactory
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.FactoryMethod
{
/**//// <summary>
/// SqlMessage工廠(ConcreteCreator)
/// </summary>
public class SqlMessageFactory : AbstractMessageFactory
{
/**//// <summary>
/// 實現工廠方法,返回SqlMessage對象
/// </summary>
/// <returns></returns>
public override AbstractMessage CreateMessage()
{
return new SqlMessage();
}
}
}
XmlMessageFactory
using System;
using System.Collections.Generic;
using System.Text;
namespace Pattern.FactoryMethod
{
/**//// <summary>
/// XmlMessage工廠(ConcreteCreator)
/// </summary>
public class XmlMessageFactory : AbstractMessageFactory
{
/**//// <summary>
/// 實現工廠方法,返回XmlMessage對象
/// </summary>
/// <returns></returns>
public override AbstractMessage CreateMessage()
{
return new XmlMessage();
}
}
}
client
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.FactoryMethod;
public partial class FactoryMethod : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
AbstractMessageFactory amf = new SqlMessageFactory();
AbstractMessage am = amf.CreateMessage();
Response.Write(am.Insert(new MessageModel("插入", DateTime.Now)));
Response.Write("<br />");
Response.Write(am.Get()[0].Message + " " + am.Get()[0].PublishTime.ToString());
Response.Write("<br />");
amf = new XmlMessageFactory();
am = amf.CreateMessage();
Response.Write(am.Insert(new MessageModel("插入", DateTime.Now)));
Response.Write("<br />");
Response.Write(am.Get()[0].Message + " " + am.Get()[0].PublishTime.ToString());
}
}
運行結果
True
SQL方式獲取Message 2007-5-4 22:34:39
True
XML方式獲取Message 2007-5-4 22:34:39
參考
http://www.dofactory.com/Patterns/PatternFactory.aspx