DataReader转换为实体的应用

代码

 －－－－DataReader转换为实体的泛型类－－－
        注意 数据库表字段名和实体类相同
         public   class  EntityTranslate
        {
             ///  用class关键字表示约束为引用类型
             ///  用struct关键字表示约束为值类型
             ///  new()默认构造函数约束：如果需要在泛型类型内部实例化类型参数的对象，
            /// 就必须对类型参数加以默认构造函数约束，除此之外别无选择。
           // 执行查询返回对象集合 
           public   static  List < TEntity >  Translate < TEntity > (IDataReader reader)  where  TEntity :  class ,  new () 
            {
                List < TEntity >  list  =   new  List < TEntity > ();
                Type entityType  =   typeof (TEntity);
                 // 创建实例
                 object  entity  =  Activator.CreateInstance(entityType);
                List < string >  attributes  =   new  List < string > ();
                Dictionary < string , PropertyInfo >  dic  =   new  Dictionary < string , PropertyInfo > ();
                 foreach  (PropertyInfo info  in  entityType.GetProperties())
                {
                    dic.Add(info.Name, info);
                }

                 string  columnName  =   string .Empty;
                 // object[] attributes = info.GetCustomAttributes(true);
                 while  (reader.Read())
                {
                    TEntity t  =   new  TEntity();
                     foreach  (KeyValuePair < string , PropertyInfo >  attribute  in  dic)
                    {
                        columnName  =  attribute.Key;
                         int  filedIndex  =   0 ;
                         while  (filedIndex  <  reader.FieldCount)
                        {

                             if  (reader.GetName(filedIndex)  ==  columnName)
                            {
                                attribute.Value.SetValue(t, reader[filedIndex],  null );
                                 break ;

                            }
                            filedIndex ++ ;


                        }
                    }
                    list.Add(t);

                }
                 return  list;

            }
        }
      实现代码：
        public   void  ReaderToEntity()
        {
             string  sql  =   " select * from T_User " ;
            IDataReader reader  =  DAO.GetReader(sql);
            List < User >  list  =  EntityTranslate.Translate < User > (reader);
             foreach  (User user  in  list)
            {
                Console.WriteLine( " 用户ID: "   +  user.Id.ToString()  +   "  用户名： "  
                 +  user.UserName  +   "  密码: "   +  user.UserPwd);
            }
            reader.Close();
        }