设计模式 - 工厂方法模式（Factory Method）

using System;
using System.Reflection;
using System.Configuration;

namespace WinApp_CSharp
{
    /**//// <summary>
    /// ProgramEntrance 的摘要说明。
    /// </summary>
    public class ProgramEntrance
    {
        /**///// <summary>
        /// 应用程序入口.
        /// </summary>
        [STAThread]
        public static void Main()
        {
            string strfactoryName = ConfigurationSettings.AppSettings["factoryName"];
        
            LogFactory factory;
            factory = (LogFactory)Assembly.Load("WinApp_CSharp").CreateInstance("WinApp_CSharp." + strfactoryName);

            Log log = factory.Create();
            log.Write();
        }
    }

    Log#region Log
    /**///// <summary>
    /// Log类
    /// </summary>
    public abstract class Log
    {
        public abstract void Write();
    }

    /**///// <summary>
    /// EventLog类
    /// </summary>
    public class EventLog:Log
    {
        public override void Write()
        {
            Console.WriteLine("EventLog Write Success!");
        }
    }
    /**///// <summary>
    /// FileLog类
    /// </summary>
    public class FileLog:Log
    {
        public override void Write()
        {
            Console.WriteLine("FileLog Write Success!");
        }
    }

    #endregion


    Log Creater#region Log Creater
    /**//**//**//// <summary>
    /// LogFactory类
    /// </summary>
    public abstract class LogFactory
    {
        public abstract Log Create();
    }

    /**//**//**//// <summary>
    /// EventFactory类
    /// </summary>
    public class EventFactory:LogFactory
    {
        public override Log Create()
        {
            return new EventLog();
        }
    }
    /**//**//**//// <summary>
    /// FileFactory类
    /// </summary>
    public class FileFactory:LogFactory
    {
        public override Log Create()
        {
            return new FileLog();
        }
    }

    #endregion
}

http://terrylee.cnblogs.com/archive/2006/01/04/310716.html
/FactoryMethod.rar