反射的用法之二

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
  </startup>
  <appSettings>

　　　　<!--<add key="IHelpConfig" value="Com.Meteor.Dal,Com.Meteor.Dal.SqlserverHelper"/>-->
　　　　<add key="IHelpConfig" value="Com.Meteor.MySql,Com.Meteor.MySql.MysqlHelper"/>

  </appSettings>
</configuration>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using Com.Meteor.Interface;
using System.Configuration;

namespace MyReflection
{
    /// <summary>
    /// metadata元数据
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("欢迎大家来流星小子博客,学习反射技术");

          //  SqlserverHelper sqlserverHelper = new SqlserverHelper();
          //  sqlserverHelper.Query();
           Console.WriteLine("-----------可配置可扩展--------------");
           string iHelperConfig = ConfigurationManager.AppSettings["IHelpConfig"];
           Assembly assembly = Assembly.Load(iHelperConfig.Split(‘,‘)[0]);//动态加载dll
           Type typeHelper = assembly.GetType(iHelperConfig.Split(‘,‘)[1]);
           Object oHelper = Activator.CreateInstance(typeHelper);
           IHelper iHelper = (IHelper)oHelper; //这句有性能损失，使用了强制类型转换
           iHelper.Query();
           Console.Read();

        }
    }
}

namespace Com.Meteor.Interface
{
    public interface IHelper
    {
        void Query();
    }
}

namespace Com.Meteor.Dal
{
    public class SqlserverHelper : IHelper
    {
        public SqlserverHelper()
        {
            Console.WriteLine("这里开始构造SqlserverHelper");
        } 
        public void Query()
        {
            Console.WriteLine("SqlserverHelper Query");
        }
    }
}

public class MysqlHelper : IHelper
    {
        public MysqlHelper()
        {
            Console.WriteLine("这里开始构造MysqlHelper");
        }
        public void Query()
        {
            Console.WriteLine("MysqlHelper Query");
        }
    }