DataReader 转为实体

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

namespace Common
{
    public static class DataReaderToEntity
    {
        /// <summary>
        /// DataReader转泛型
        /// </summary>
        /// <typeparam name="T">传入的实体类</typeparam>
        /// <param name="objReader">DataReader对象</param>
        /// <returns></returns>
        public static IList<T> ReaderToList<T>(IDataReader objReader)
        {
            using (objReader)
            {
                List<T> list = new List<T>();

                //获取传入的数据类型
                Type modelType = typeof(T);

                //遍历DataReader对象
                while (objReader.Read())
                {
                    //使用与指定参数匹配最高的构造函数，来创建指定类型的实例
                    T model = Activator.CreateInstance<T>();
                    for (int i = 0; i < objReader.FieldCount; i++)
                    {
                        //判断字段值是否为空或不存在的值
                        if (!IsNullOrDBNull(objReader[i]))
                        {
                            //匹配字段名
                            PropertyInfo pi = modelType.GetProperty(objReader.GetName(i), BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase);
                            if (pi != null)
                            {
                                //绑定实体对象中同名的字段
                                pi.SetValue(model, CheckType(objReader[i], pi.PropertyType), null);
                            }
                        }
                    }
                    list.Add(model);
                }
                return list;
            }
        }

        /// <summary>
        /// 对可空类型进行判断转换(*要不然会报错)
        /// </summary>
        /// <param name="value">DataReader字段的值</param>
        /// <param name="conversionType">该字段的类型</param>
        /// <returns></returns>
        private static object CheckType(object value, Type conversionType)
        {
            if (conversionType.IsGenericType && conversionType.GetGenericTypeDefinition() == typeof(Nullable<>))
            {
                if (value == null)
                    return null;
                var nullableConverter = new System.ComponentModel.NullableConverter(conversionType);
                conversionType = nullableConverter.UnderlyingType;
            }
            return Convert.ChangeType(value, conversionType);
        }

        /// <summary>
        /// 判断指定对象是否是有效值
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        private static bool IsNullOrDBNull(object obj)
        {
            return (obj == null || (obj is DBNull)) ? true : false;
        }

        /// <summary>
        /// DataReader转模型
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="objReader"></param>
        /// <returns></returns>
        public static T ReaderToModel<T>(IDataReader objReader)
        {

            using (objReader)
            {
                if (objReader.Read())
                {
                    var modelType = typeof(T);
                    var model = Activator.CreateInstance<T>();
                    for (var i = 0; i < objReader.FieldCount; i++)
                    {
                        if (!IsNullOrDBNull(objReader[i]))
                        {
                            var pi = modelType.GetProperty(objReader.GetName(i), BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase);
                            if (pi != null)
                            {
                                pi.SetValue(model, CheckType(objReader[i], pi.PropertyType), null);
                            }
                        }
                    }
                    return model;
                }
            }
            return default(T);
        }
    }
}