乐在其中设计模式(C#) - 工厂方法模式(Factory Method Pattern)

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[align=center]乐在其中设计模式(C#) - 工厂方法模式(Factory Method Pattern)[/align]

作者：webabcd

介绍
定义一个用于创建对象的接口，让子类决定将哪一个类实例化。Factory Method使一个类的实例化延迟到其子类。

示例
有SqlMessage和XmlMessage，用Factory Method来实例化它们。



MessageModel


using System;


using System.Collections.Generic;


using System.Text;




namespace Pattern.FactoryMethod


{


/// <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.FactoryMethod


{


/// <summary>


/// 操作Message抽象类（Product）


/// </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.FactoryMethod


{


/// <summary>


/// Sql方式操作Message（ConcreteProduct）


/// </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.FactoryMethod


{


/// <summary>


/// Xml方式操作Message（ConcreteProduct）


/// </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;


}


}


}

AbstractMessageFactory


using System;


using System.Collections.Generic;


using System.Text;




namespace Pattern.FactoryMethod


{


/// <summary>


/// 抽象Message工厂（Creator）


/// </summary>


public abstract class AbstractMessageFactory


{


// An Operation




/// <summary>


/// 工厂方法


/// </summary>


/// <returns>AbstractMessage</returns>


public abstract AbstractMessage CreateMessage();


}


}

SqlMessageFactory


using System;


using System.Collections.Generic;


using System.Text;




namespace Pattern.FactoryMethod


{


/// <summary>


/// SqlMessage工厂（ConcreteCreator）


/// </summary>


public class SqlMessageFactory : AbstractMessageFactory


{


/// <summary>


/// 实现工厂方法，返回SqlMessage对象


/// </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工厂（ConcreteCreator）


/// </summary>


public class XmlMessageFactory : AbstractMessageFactory


{


/// <summary>


/// 实现工厂方法，返回XmlMessage对象


/// </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());


}


}

运行结果
True
SQL方式获取Message 2007-5-4 22:34:39
True
XML方式获取Message 2007-5-4 22:34:39

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

OK
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