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

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

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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