泛型集合与DataSet相互转换

一、泛型转DataSet

/// <summary> 
        /// 泛型集合转换DataSet 
        /// </summary> 
        /// <typeparam name="T"></typeparam> 
        /// <param name="list">泛型集合</param> 
        /// <returns></returns> 
        /// 
        public static DataSet ToDataSet<T>(List<T> list)
        {
            return ToDataSet1<T>(list, null);
        }
        /// <summary> 
        /// 泛型集合转换DataSet,并指定需要转换的字段
        /// </summary> 
        /// <typeparam name="T"></typeparam> 
        /// <param name="p_List">泛型集合</param> 
        /// <param name="p_PropertyName">待转换属性名数组</param> 
        /// <returns></returns> 
        public static DataSet ToDataSet1<T>(List<T> p_List, params string[] p_PropertyName)
        {
            List<string> propertyNameList = new List<string>();
            if (p_PropertyName != null)
                propertyNameList.AddRange(p_PropertyName);

            DataSet result = new DataSet();
            DataTable _DataTable = new DataTable();
            if (p_List.Count > 0)
            {
                Type type = typeof(T);
                PropertyInfo[] propertys = type.GetProperties();
                foreach (PropertyInfo pi in propertys)
                {
                    if (propertyNameList.Count == 0)
                    {
                        // 没有指定属性的情况下全部属性都要转换 
                        _DataTable.Columns.Add(pi.Name, pi.PropertyType);
                    }
                    else
                    {
                        if (propertyNameList.Contains(pi.Name))
                            _DataTable.Columns.Add(pi.Name, pi.PropertyType);
                    }
                }

                for (int i = 0; i < p_List.Count; i++)
                {
                    ArrayList tempList = new ArrayList();
                    foreach (PropertyInfo pi in propertys)
                    {
                        if (propertyNameList.Count == 0)
                        {
                            object obj = pi.GetValue(p_List[i], null);
                            tempList.Add(obj);
                        }
                        else
                        {
                            if (propertyNameList.Contains(pi.Name))
                            {
                                object obj = pi.GetValue(p_List[i], null);
                                tempList.Add(obj);
                            }
                        }
                    }
                    object[] array = tempList.ToArray();
                    _DataTable.LoadDataRow(array, true);
                }
            }
            result.Tables.Add(_DataTable);
            return result;
        }
 

        //调用
       // List<实体类> List = new List<实体类>();
        //DataSet ds = ToDataSet(List);

二、DataSet转泛型

第一种通过索引

/// <summary> 
        /// DataSet装换为泛型集合 
        /// </summary> 
        /// <typeparam name="T"></typeparam> 
        /// <param name="p_DataSet">DataSet</param> 
        /// <param name="p_TableIndex">待转换数据表索引</param> 
        /// <returns></returns> 
        public static List<T> DataSetToList<T>(DataSet p_DataSet, int p_TableIndex)
        {
            if (p_DataSet == null || p_DataSet.Tables.Count < 0)
                return null;
            if (p_TableIndex > p_DataSet.Tables.Count - 1)
                return null;
            if (p_TableIndex < 0)
                p_TableIndex = 0;

            DataTable p_Data = p_DataSet.Tables[p_TableIndex];
            // 返回值初始化 
            List<T> result = new List<T>();
            for (int j = 0; j < p_Data.Rows.Count; j++)
            {
                T _t = (T)Activator.CreateInstance(typeof(T));
                PropertyInfo[] propertys = _t.GetType().GetProperties();
                foreach (PropertyInfo pi in propertys)
                {
                    for (int i = 0; i < p_Data.Columns.Count; i++)
                    {
                        // 属性与字段名称一致的进行赋值 
                        if (pi.Name.Equals(p_Data.Columns[i].ColumnName.ToUpper()))
                        {
                            // 数据库NULL值单独处理 
                            if (p_Data.Rows[j][i] != DBNull.Value)
                            {
                                if (p_Data.Rows[j][i].GetType().Name == "Double")
                                {
                                    pi.SetValue(_t, Convert.ToDecimal(p_Data.Rows[j][i]), null);
                                }
                                else
                                {
                                    pi.SetValue(_t, p_Data.Rows[j][i], null);
                                }
                            }
                            else
                                pi.SetValue(_t, null, null);
                            break;
                        }
                    }
                }
                result.Add(_t);
            }
            return result;
        }
        //调用
        DataSet ds = new DataSet();
        List<实体类> list = new  List<实体类>();
        dddss.Tables.Add(dt);
        //组合条件筛选完成之后转换为实体集合
        list = DataSetToList<实体类>(ds, 索引);

第二种通过数据表名称

/// <summary> 
        /// DataSet装换为泛型集合 
        /// </summary> 
        /// <typeparam name="T"></typeparam> 
        /// <param name="p_DataSet">DataSet</param> 
        /// <param name="p_TableName">待转换数据表名称</param> 
        /// <returns></returns> 
        /// 2008-08-01 22:47 HPDV2806 
        public static List<T> DataSetToList<T>(DataSet p_DataSet, string p_TableName)
        {
            int _TableIndex = 0;
            if (p_DataSet == null || p_DataSet.Tables.Count < 0)
                return null;
            if (string.IsNullOrEmpty(p_TableName))
                return null;
            for (int i = 0; i < p_DataSet.Tables.Count; i++)
            {
                // 获取Table名称在Tables集合中的索引值 
                if (p_DataSet.Tables[i].TableName.Equals(p_TableName))
                {
                    _TableIndex = i;
                    break;
                }
            }
            return DataSetToList<T>(p_DataSet, _TableIndex);
        }
 /// <summary> 
        /// DataSet装换为泛型集合 
        /// </summary> 
        /// <typeparam name="T"></typeparam> 
        /// <param name="p_DataSet">DataSet</param> 
        /// <param name="p_TableIndex">待转换数据表索引</param> 
        /// <returns></returns> 
        /// 2008-08-01 22:46 HPDV2806 
        public static List<T> DataSetToList<T>(DataSet p_DataSet, int p_TableIndex)
        {
            if (p_DataSet == null || p_DataSet.Tables.Count < 0)
                return null;
            if (p_TableIndex > p_DataSet.Tables.Count - 1)
                return null;
            if (p_TableIndex < 0)
                p_TableIndex = 0;

            DataTable p_Data = p_DataSet.Tables[p_TableIndex];
            // 返回值初始化 
            List<T> result = new List<T>();
            for (int j = 0; j < p_Data.Rows.Count; j++)
            {
                T _t = (T)Activator.CreateInstance(typeof(T));
                PropertyInfo[] propertys = _t.GetType().GetProperties();
                foreach (PropertyInfo pi in propertys)
                {
                    for (int i = 0; i < p_Data.Columns.Count; i++)
                    {
                        // 属性与字段名称一致的进行赋值 
                        if (pi.Name.Equals(p_Data.Columns[i].ColumnName.ToUpper()))
                        {
                            // 数据库NULL值单独处理 
                            if (p_Data.Rows[j][i] != DBNull.Value)
                            {
                                if (p_Data.Rows[j][i].GetType().Name == "Double")
                                {
                                    pi.SetValue(_t, Convert.ToDecimal(p_Data.Rows[j][i]), null);
                                }
                                else
                                {
                                    pi.SetValue(_t, p_Data.Rows[j][i], null);
                                }
                            }
                            else
                                pi.SetValue(_t, null, null);
                            break;
                        }
                    }
                }
                result.Add(_t);
            }
            return result;
        }
        //调用
        DataSet ds = new DataSet();
        List<实体类> list = new  List<实体类>();
        dddss.Tables.Add(dt);
        //组合条件筛选完成之后转换为实体集合
        list = DataSetToList<实体类>(ds, 表名);