利用反射工厂来产生对象

 public class InstanceFactory
    {
        public static DBFactory Instance(string InstanceType)
        {
            Type t = Type.GetType(InstanceType);
            DBFactory DBInstance = (DBFactory)Activator.CreateInstance(t);
            return DBInstance;
        }
    }


public static void Main()
        {

            DBFactory db = InstanceFactory.Instance("Project1.sqlserver");
            DBOperator dbo = new DBOperator(db);
            dbo.Open("server=MS124716;database=test;uid=sa;pwd=12");
            DataTable dt = dbo.ExecSQL("select * from login");
            foreach (DataRow dr in dt.Rows)
            {
                Console.Write(dr["name"].ToString());
                Console.Write(dr["pwd"].ToString());
            }
           
            Console.Read();

           
          
            
        }