关于设计模式，园子有太多的介绍了，我就不去摆文弄墨了。

关于工厂模式，算是最简单，最好理解的设计模式了，当然，可能是最多的设计模式了。我这里说的并不是这个模式的用法，或者见解，这是个人对于这个模式的一些用法的改进而已。

好了，入正题。想必，可能大多数人写工厂模式的代码都是如此。但是，如果再增加一个IPlant的类，就必须地增加if条件判断。对于我这种对代码有洁癖的人，实在受不了。

namespace FactoryMode{    class Program    {        static void Main(string[] args)        {            var plant = PlantFactory.GetPlant("Jd");        }    }    public interface IPlant    {        void DownLoad();        void SendBackMsg();    }    public class PlantFactory    {        public static IPlant GetPlant(string plantName)        {            if (plantName == "Jd")                return new JdPlant();            if (plantName == "Tb")                return new TbPlant();            else                return null;        }    }    public class JdPlant : IPlant    {        public void DownLoad()        {            Console.WriteLine("Jd_DownLoad");            //throw new NotImplementedException();        }        public void SendBackMsg()        {            Console.WriteLine("Jd_SendBackMsg");            //throw new NotImplementedException();        }    }    public class TbPlant : IPlant    {        public void DownLoad()        {            Console.WriteLine("Tb_DownLoad");            //throw new NotImplementedException();        }        public void SendBackMsg()        {            Console.WriteLine("Tb_SendBackMsg");            //throw new NotImplementedException();        }    }} 改进后的代码:

namespace FactoryMode{    class Program    {        static void Main(string[] args)        {            var plant = PlantFactory.GetPlant("Jd");        }    }    public interface IPlant    {        void DownLoad();        void SendBackMsg();    }    public class PlantFactory    {        private static Dictionary
      
        plantDictionary = new Dictionary
       
        ();        public PlantFactory()        {            plantDictionary.Add("Jd", typeof(JdPlant));            plantDictionary.Add("Tb", typeof(TbPlant));        }        public static IPlant GetPlant(string plantName)        {            IPlant plant = null;            if (plantDictionary.Keys.Contains(plantName))            {                plant = (IPlant)Activator.CreateInstance(plantDictionary[plantName]);            }            return plant;        }    }    public class JdPlant : IPlant    {        public void DownLoad()        {            Console.WriteLine("Jd_DownLoad");            //throw new NotImplementedException();        }        public void SendBackMsg()        {            Console.WriteLine("Jd_SendBackMsg");            //throw new NotImplementedException();        }    }    public class TbPlant : IPlant    {        public void DownLoad()        {            Console.WriteLine("Tb_DownLoad");            //throw new NotImplementedException();        }        public void SendBackMsg()        {            Console.WriteLine("Tb_SendBackMsg");            //throw new NotImplementedException();        }    }}