不使用反射的依赖获取方法（转摘）

示例（有个程序，既可以使用Windows风格外观，又可以使用Mac风格外观，而内部业务是一样的。）：

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;

namespace Szh.DI.DependencyLocate
{
    public interface IButton
    {
        string ShowInfo();   
    }
    public interface IWindow
    {
        string ShowInfo();
    }
    public interface ITextBox
    {
        string ShowInfo();
    }
    public interface IFactory
    {
        IWindow MakeWindow();
        IButton MakeButton();
        ITextBox MakeTextbox();

    }
    public class WinFactory:IFactory
    {
        public IWindow MakeWindow()
        {
            return new WinWindow();
        }
        public IButton MakeButton()
        {
            return new WinButton();
        }
        public ITextBox MakeTextbox()
        {
            return new WinTextbox();
        }
    }
    public class MacFactory:IFactory
    {
        public IWindow MakeWindow()
        {
            return new MacWindow();
        }
        public IButton MakeButton()
        {
            return new MacButtton();
        }
        public ITextBox MakeTextbox()
        {
            return new MacTextbox();
        }

    }
    internal static class FactoryContainer
    {
        public static IFactory factory { get; private set; }         
        static FactoryContainer()     
        {           
            XmlDocument xmlDoc = new XmlDocument();  
            xmlDoc.Load(".\\Config.xml");
            //XmlNode xmlNode = xmlDoc.ChildNodes[1].ChildNodes[0].ChildNodes[0];   
            XmlNode xmlNode3 = xmlDoc.ChildNodes[0];
            XmlNode xmlNode2 = xmlDoc.ChildNodes[1];
            XmlNode xmlNode1 = xmlNode2.ChildNodes[0];
            XmlNode xmlNode = xmlNode1.ChildNodes[0];
            if ("Windows" == xmlNode.Value)             
            {               
                factory = new WinFactory();             
            }            
            else if ("Mac" == xmlNode.Value)           
            {                 
                factory = new MacFactory();             
            }          
            else            
            {                 
                throw new Exception("Factory Init Error");         
            }      
        }
    }
    public class WinButton:IButton
    {
        public string _description { get;set; }
        public WinButton()
        {
            this._description ="Windows style button!";
        }
        public string ShowInfo()
        {
            return this._description;
        }
    }
    public class MacButtton:IButton
    {
        public string _description{get;set;}
        public MacButtton()
        {
            this._description = "Mac style button!";
        }
        public string ShowInfo()
        {
            return this._description;
        }

    }
    public class WinWindow:IWindow
    {
        public string _description { get; set; }
        public WinWindow()
        {
            this._description = "Win style window";
        }
        public string ShowInfo()
        {
            return this._description;
        }
    }
    public class MacWindow:IWindow
    {
        public string _decription { get; set; }
        public MacWindow()
        {
            this._decription = "Mac style window";
        }
        public string ShowInfo()
        {
            return this._decription;
        }
    }
    public class WinTextbox:ITextBox
    {
        public string _decription { get; set; }
        public WinTextbox()
        {
            this._decription = "Win style textbox";
        }
        public string ShowInfo()
        {
            return this._decription;
        }
    }
    public class MacTextbox:ITextBox
    {
        public string _decription { get; set; }
        public MacTextbox()
        {
            this._decription = "Mac style textbox";
        }
        public string ShowInfo()
        {
            return this._decription;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            IFactory factory = FactoryContainer.factory;
            IWindow window = factory.MakeWindow();
            Console.WriteLine("创建 " + window.ShowInfo());
            IButton button = factory.MakeButton();
            Console.WriteLine("创建 " + button.ShowInfo());
            ITextBox textbox = factory.MakeTextbox();
            Console.WriteLine("创建 " + textbox.ShowInfo());

            Console.Read();

        }
    }
}

配置文件 Config.xml ：

<?xml version="1.0" encoding="utf-8" ?>
<config>
 <window>UbuntuWindow</window>
 <button>MacButton</button>
 <textBox>MacTextBox</textBox>
</config>

缺点：当新添加一种风格时，比如UbuntuWindow，UbuntuButton，UbuntuTextBox时，除了修改配置文件之外，还必须修改FactoryContainer 类，在其中增加处理分支。这破坏了OCP。使用反射机制可以完美的解决这个问题。见依赖注入篇。