using System;using System.Collections.Generic;using System.Data;using System.Linq;using System.Reflection;using System.Text;namespace PORM.Data{    /// <summary>    /// 常用映射关系帮助类    /// </summary>    public class CommonMap    {        /// <summary>        ///         /// </summary>        /// <typeparam name="T"></typeparam>        /// <param name="dReader"></param>        /// <returns></returns>        public static IEnumerable<T> MapToIEnumerable<T>(IDataReader dReader) where T : class        {            using (dReader)            {                List<string> drFields = new List<string>(dReader.FieldCount);                for (int i = 0; i < dReader.FieldCount; i++)                {                    drFields.Add(dReader.GetName(i).ToLower());                }                while (dReader.Read())                {                    T model = Activator.CreateInstance<T>();                    foreach (PropertyInfo pi in model.GetType().GetProperties(BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance))                    {                        if (drFields.Contains(pi.Name.ToLower()))                        {                            if (pi.PropertyType.IsEnum)                            {                                object enumName = Enum.ToObject(pi.PropertyType, pi.GetValue(model, null));                                pi.SetValue(model, enumName, null);                            }                            else                            {                                if (!IsNullOrEmptyOrDBNull(dReader[pi.Name]))                                {                                    pi.SetValue(model, MapNullableType(dReader[pi.Name], pi.PropertyType), null);                                }                            }                        }                    }                    yield return model;                }            }        }        /// <summary>        ///         /// </summary>        /// <typeparam name="T"></typeparam>        /// <param name="table"></param>        /// <returns></returns>        public static IEnumerable<T> MapToIEnumerable<T>(DataTable table) where T : class        {            foreach (DataRow row in table.Rows)            {                yield return MapToModel<T>(row);            }        }        /// <summary>        ///         /// </summary>        /// <typeparam name="T"></typeparam>        /// <param name="dReader"></param>        /// <returns></returns>        public static T MapToModel<T>(IDataReader dReader) where T : class        {            using (dReader)            {                if (dReader.Read())                {                    List<string> drFields = new List<string>(dReader.FieldCount);                    for (int i = 0; i < dReader.FieldCount; i++)                    {                        drFields.Add(dReader.GetName(i).ToLower());                    }                    T model = Activator.CreateInstance<T>();                    foreach (PropertyInfo pi in model.GetType().GetProperties(BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance))                    {                        if (drFields.Contains(pi.Name.ToLower()))                        {                            if (pi.PropertyType.IsEnum)                            {                                object enumName = Enum.ToObject(pi.PropertyType, pi.GetValue(model, null));                                pi.SetValue(model, enumName, null);                            }                            else                            {                                if (!IsNullOrEmptyOrDBNull(dReader[pi.Name]))                                {                                    pi.SetValue(model, MapNullableType(dReader[pi.Name], pi.PropertyType), null);                                }                            }                        }                    }                    return model;                }            }            return default(T);        }        /// <summary>        ///         /// </summary>        /// <typeparam name="T"></typeparam>        /// <param name="dRow"></param>        /// <returns></returns>        public static T MapToModel<T>(DataRow dRow) where T : class        {            try            {                List<string> drItems = new List<string>(dRow.ItemArray.Length);                for (int i = 0; i < dRow.ItemArray.Length; i++)                {                    drItems.Add(dRow.Table.Columns[i].ColumnName.ToLower());                }                T model = Activator.CreateInstance<T>();                foreach (PropertyInfo pi in model.GetType().GetProperties(BindingFlags.GetProperty | BindingFlags.Public | BindingFlags.Instance))                {                    if (drItems.Contains(pi.Name.ToLower()))                    {                        if (pi.PropertyType.IsEnum) //属性类型是否表示枚举                        {                            object enumName = Enum.ToObject(pi.PropertyType, pi.GetValue(model, null));                            pi.SetValue(model, enumName, null); //获取枚举值，设置属性值                        }                        else                        {                            if (!IsNullOrEmptyOrDBNull(dRow[pi.Name]))                            {                                pi.SetValue(model, MapNullableType(dRow[pi.Name], pi.PropertyType), null);                            }                        }                    }                }                return model;            }            catch (Exception ex)            {                throw ex;            }        }        /// <summary>        ///         /// </summary>        /// <param name="value"></param>        /// <param name="mType"></param>        /// <returns></returns>        public static object MapNullableType(object value, Type mType)        {            if (mType.IsGenericType && mType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))            {                if (IsNullOrEmptyOrDBNull(value))                    return null;                System.ComponentModel.NullableConverter nullableConverter = new System.ComponentModel.NullableConverter(mType);                mType = nullableConverter.UnderlyingType;            }            if (mType == typeof(bool) || mType == typeof(Boolean))            {                if (value is string)                {                    if (value.ToString() == "1")                        return true;                    else                        return false;                }            }            if (mType.IsEnum) //属性类型是否表示枚举            {                int intvalue;                if (int.TryParse(value.ToString(), out intvalue))                    return Enum.ToObject(mType, Convert.ToInt32(value));                else                    return System.Enum.Parse(mType, value.ToString(), false);            }            return Convert.ChangeType(value, mType);        }        /// <summary>        ///         /// </summary>        /// <typeparam name="T"></typeparam>        /// <param name="value"></param>        /// <returns></returns>        public static T MapType<T>(object value)        {            Type type = typeof(T);            if (CommonMap.IsNullOrEmptyOrDBNull(value))                value = http://www.mamicode.com/type.IsValueType ? Activator.CreateInstance(type) : null;"obj"></param>        /// <returns></returns>        public static bool IsNullOrEmptyOrDBNull(object obj)        {            return ((obj is DBNull) || obj == null || string.IsNullOrEmpty(obj.ToString())) ? true : false;        }    }}