反射

 

一、格式：

Assembly.Load("程序集名称").CreateInstance("命名空间.名称")

 

程序集：创建类库的名称

 

命名空间：

 

二、反射解析

using System.Reflection;

三、实例demo

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


using System.Reflection;//引用反射
using System.Configuration;//配置文件

namespace ITOO_DAL
{
    class DataAccess
    {
        //给变量字段赋值，读取配置文件中的值，只读
        private static readonly string db = ConfigurationManager.AppSettings["DB"];//读取配置文件
        //确定程序集名称，只读
       private static readonly string AssemblyName = "ITOO_DAL";

        //给程序集赋值
        private static readonly string db = "Sqlserver";

        //通过接口，反射创建User类
        public static IUser CreateUser()
        {
            string className = AssemblyName + "." +db+ "User";//ITOO_DAL.User
            return (IUser) Assembly.Load(AssemblyName).CreateInstance(className);
        }
        //通过接口，反射创建department类
        public static IDepartment CreateDepartment()
        {
            string className = AssemblyName + "." + db + "Department";
            return (IDepartment) AssemblyName.Load(AssemblyName).CreatInstance(className);
        }
    }
}

　　配置文件需要给DB赋值

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
    </startup>
  
  <!--给程序里面的变量赋值-->
  <appSettings>
    <add key="DB" value="Sqlserver"/>
  </appSettings>
  
</configuration>

四、优点

　　让类的实例化变的更加灵活，代码解耦和。