NPOI Excel Helper

 /// <summary>
    /// NPOIExcel帮助类
    /// </summary>
    public class NPOIExcelHelper
    {
        /// <summary>
        /// DataTable导出到Excel文件
        /// </summary>
        /// <param name="dtSource">源DataTable</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strFileName">保存位置</param>
        public static void DataTableToExcel(DataTable dtSource, string strHeaderText, string strFileName)
        {
            ExcelFileSuffixType suffix = default(ExcelFileSuffixType);
            if (strFileName.IndexOf(".xlsx") > 0) // 2007版本
                suffix = ExcelFileSuffixType.xlsx;
            else if (strFileName.IndexOf(".xls") > 0) // 2003版本
                suffix = ExcelFileSuffixType.xls;

            using (MemoryStream ms = DataTableToExcelStream(dtSource, strHeaderText, suffix))
            {
                using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write))
                {
                    byte[] data = ms.ToArray();
                    fs.Write(data, 0, data.Length);
                    fs.Flush();
                }
            }
        }

        /// <summary>
        /// DataGridView导出到Excel文件
        /// </summary>
        /// <param name="dtSource">源DataTGridview</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strFileName">保存位置</param>
        public static void DataGridViewToExcel(DataGridView myDgv, string strHeaderText, string strFileName)
        {
            ExcelFileSuffixType suffix = default(ExcelFileSuffixType);
            if (strFileName.IndexOf(".xlsx") > 0) // 2007版本
                suffix = ExcelFileSuffixType.xlsx;
            else if (strFileName.IndexOf(".xls") > 0) // 2003版本
                suffix = ExcelFileSuffixType.xls;

            using (MemoryStream ms = DataGridViewToExcelStream(myDgv, strHeaderText, suffix))
            {
                using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write))
                {
                    byte[] data = ms.ToArray();
                    fs.Write(data, 0, data.Length);
                    fs.Flush();
                }
            }
        }

        /// <summary>
        /// 将excel文件导入至DataTable
        /// </summary>
        /// <param name="strFileName">excel文件全路径</param>
        /// <returns></returns>
        public static DataTable ExcelToDataTable(string strFileName)
        {
            DataTable dt = new DataTable();

            IWorkbook workbook = null;

            using (FileStream file = new FileStream(strFileName, FileMode.Open, FileAccess.Read))
            {
#if New_NPOI
                if (strFileName.IndexOf(".xlsx") > 0) // 2007版本
                    workbook = new XSSFWorkbook(file);
                else if (strFileName.IndexOf(".xls") > 0) // 2003版本
                    workbook = new HSSFWorkbook(file);
#endif
#if Old_NPOI
                workbook = new HSSFWorkbook(file);
#endif
            }

            ISheet sheet = workbook.GetSheetAt(0);
            System.Collections.IEnumerator rows = sheet.GetRowEnumerator();

            IRow headerRow = sheet.GetRow(0);
            int cellCount = headerRow.LastCellNum;

            for (int j = 0; j < cellCount; j++)
            {
                ICell cell = headerRow.GetCell(j);
                dt.Columns.Add(cell.ToString());
            }

            for (int i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum; i++)
            {
                IRow row = sheet.GetRow(i);
                DataRow dataRow = dt.NewRow();

                for (int j = row.FirstCellNum; j < cellCount; j++)
                {
                    if (row.GetCell(j) != null)
                        dataRow[j] = row.GetCell(j).ToString();
                }

                dt.Rows.Add(dataRow);
            }

            return dt;
        }

        #region private
        /// <summary>
        /// DataTable导出到Excel的MemoryStream
        /// </summary>
        /// <param name="dtSource">源DataTable</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strHeaderText">excel文件后缀类型</param>
        private static MemoryStream DataTableToExcelStream(DataTable dtSource, string strHeaderText, ExcelFileSuffixType suffix)
        {
            ISheet sheet = null;
            IWorkbook workbook = null;
            ICellStyle cellStyle = null;
            IDataFormat dataFormat = null;

#if New_NPOI
            if (suffix == ExcelFileSuffixType.xls)
                workbook = new HSSFWorkbook();
            else if (suffix == ExcelFileSuffixType.xlsx)
                workbook = new XSSFWorkbook();
#endif
#if Old_NPOI
            workbook = new HSSFWorkbook();
#endif

            sheet = workbook.CreateSheet();

            cellStyle = workbook.CreateCellStyle();
            dataFormat = workbook.CreateDataFormat();
            cellStyle.DataFormat = dataFormat.GetFormat("yyyy-mm-dd");

            //取得列宽
            int[] arrColWidth = new int[dtSource.Columns.Count];
            foreach (DataColumn item in dtSource.Columns)
            {
                arrColWidth[item.Ordinal] = Encoding.GetEncoding(936).GetBytes(item.ColumnName.ToString()).Length;
            }
            for (int i = 0; i < dtSource.Rows.Count; i++)
            {
                for (int j = 0; j < dtSource.Columns.Count; j++)
                {
                    int intTemp = Encoding.GetEncoding(936).GetBytes(dtSource.Rows[i][j].ToString()).Length;
                    if (intTemp > arrColWidth[j])
                    {
                        arrColWidth[j] = intTemp;
                    }
                }
            }
            int rowIndex = 0;
            foreach (DataRow row in dtSource.Rows)
            {
                #region 新建表，填充表头，填充列头，样式
                if (rowIndex == 65535 || rowIndex == 0)
                {
                    if (rowIndex != 0)
                    {
                        sheet = workbook.CreateSheet();
                    }

                    #region 表头及样式
                    {
                        IRow headerRow = sheet.CreateRow(0);
                        headerRow.HeightInPoints = 25;
                        headerRow.CreateCell(0).SetCellValue(strHeaderText);

                        ICellStyle headStyle = workbook.CreateCellStyle();
                        //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                        IFont font = workbook.CreateFont();
                        font.FontHeightInPoints = 20;
#if New_NPOI
                        font.IsBold = true;
#endif
#if Old_NPOI
                        font.Boldweight = 700;
#endif
                        headStyle.SetFont(font);
                        headerRow.GetCell(0).CellStyle = headStyle;
                        //sheet.AddMergedRegion(new Region(0, 0, 0, dtSource.Columns.Count - 1));
                        //headerRow.Dispose();
                    }
                    #endregion

                    #region 列头及样式
                    {
                        IRow headerRow = sheet.CreateRow(1);
                        ICellStyle headStyle = workbook.CreateCellStyle();
                        //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                        IFont font = workbook.CreateFont();
                        font.FontHeightInPoints = 10;
#if New_NPOI
                        font.IsBold = true;
#endif
#if Old_NPOI
                        font.Boldweight = 700;
#endif
                        headStyle.SetFont(font);
                        foreach (DataColumn column in dtSource.Columns)
                        {
                            headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
                            headerRow.GetCell(column.Ordinal).CellStyle = headStyle;

                            //设置列宽
                            //  sheet.SetColumnWidth(column.Ordinal, (arrColWidth[column.Ordinal] + 1) * 256); 
                        }
                        // headerRow.Dispose();
                    }
                    #endregion

                    rowIndex = 2;
                }
                #endregion

                #region 填充内容
                IRow dataRow = sheet.CreateRow(rowIndex);
                foreach (DataColumn column in dtSource.Columns)
                {
                    ICell newCell = dataRow.CreateCell(column.Ordinal);

                    string drValue = row[column].ToString();

                    switch (column.DataType.ToString())
                    {
                        case "System.String"://字符串类型
                            if (drValue.Length > 30000)
                                drValue = drValue.Substring(0, 30000);
                            newCell.SetCellValue(drValue);
                            break;
                        case "System.DateTime"://日期类型
                            System.DateTime dateV;
                            System.DateTime.TryParse(drValue, out dateV);
                            newCell.SetCellValue(dateV);

                            newCell.CellStyle = cellStyle;//格式化显示
                            break;
                        case "System.Boolean"://布尔型
                            bool boolV = false;
                            bool.TryParse(drValue, out boolV);
                            newCell.SetCellValue(boolV);
                            break;
                        case "System.Int16"://整型
                        case "System.Int32":
                        case "System.Int64":
                        case "System.Byte":
                            int intV = 0;
                            int.TryParse(drValue, out intV);
                            newCell.SetCellValue(intV);
                            break;
                        case "System.Decimal"://浮点型
                        case "System.Double":
                            double doubV = 0;
                            double.TryParse(drValue, out doubV);
                            newCell.SetCellValue(doubV);
                            break;
                        case "System.DBNull"://空值处理
                            newCell.SetCellValue("");
                            break;
                        default:
                            newCell.SetCellValue("");
                            break;
                    }

                }
                #endregion

                rowIndex++;
            }

            MemoryStream ms = new MemoryStream();
            workbook.Write(ms);
            ms.Flush();
#if New_NPOI
            workbook.Close();
#endif
            return ms;
        }

        /// <summary>
        /// DataTable导出到Excel的MemoryStream
        /// </summary>
        /// <param name="myDgv">源DataTable</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strHeaderText">excel文件后缀类型</param>
        private static MemoryStream DataGridViewToExcelStream(DataGridView myDgv, string strHeaderText, ExcelFileSuffixType suffix)
        {
            ISheet sheet = null;
            IWorkbook workbook = null;
            ICellStyle cellStyle = null;
            IDataFormat dataFormat = null;

#if New_NPOI
            if (suffix == ExcelFileSuffixType.xls)
                workbook = new HSSFWorkbook();
            else if (suffix == ExcelFileSuffixType.xlsx)
                workbook = new XSSFWorkbook();
#endif
#if Old_NPOI
            workbook = new HSSFWorkbook();
#endif
            sheet = workbook.CreateSheet();

            cellStyle = workbook.CreateCellStyle();
            dataFormat = workbook.CreateDataFormat();
            cellStyle.DataFormat = dataFormat.GetFormat("yyyy-mm-dd");

            //取得列宽
            int[] arrColWidth = new int[myDgv.Columns.Count];
            foreach (DataGridViewColumn item in myDgv.Columns)
            {
                arrColWidth[item.Index] = Encoding.GetEncoding(936).GetBytes(item.HeaderText.ToString()).Length;
            }
            for (int i = 0; i < myDgv.Rows.Count; i++)
            {
                for (int j = 0; j < myDgv.Columns.Count; j++)
                {
                    int intTemp = Encoding.GetEncoding(936).GetBytes(myDgv.Rows[i].Cells[j].ToString()).Length;
                    if (intTemp > arrColWidth[j])
                    {
                        arrColWidth[j] = intTemp;
                    }
                }
            }
            int rowIndex = 0;
            foreach (DataGridViewRow row in myDgv.Rows)
            {
                #region 新建表，填充表头，填充列头，样式
                if (rowIndex == 65535 || rowIndex == 0)
                {
                    if (rowIndex != 0)
                    {
                        sheet = workbook.CreateSheet();
                    }

                    #region 表头及样式
                    {
                        IRow headerRow = sheet.CreateRow(0);
                        headerRow.HeightInPoints = 25;
                        headerRow.CreateCell(0).SetCellValue(strHeaderText);

                        ICellStyle headStyle = workbook.CreateCellStyle();
                        //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                        IFont font = workbook.CreateFont();
                        font.FontHeightInPoints = 20;
#if New_NPOI
                        font.IsBold = true;
#endif
#if Old_NPOI
                        font.Boldweight = 700;
#endif
                        headStyle.SetFont(font);
                        headerRow.GetCell(0).CellStyle = headStyle;
                        // sheet.AddMergedRegion(new Region(0, 0, 0, dtSource.Columns.Count - 1));
                        //headerRow.Dispose();
                    }
                    #endregion


                    #region 列头及样式
                    {
                        IRow headerRow = sheet.CreateRow(1);
                        ICellStyle headStyle = workbook.CreateCellStyle();
                        //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                        IFont font = workbook.CreateFont();
                        font.FontHeightInPoints = 10;
#if New_NPOI
                        font.IsBold = true;
#endif
#if Old_NPOI
                        font.Boldweight = 700;
#endif
                        headStyle.SetFont(font);
                        foreach (DataGridViewColumn column in myDgv.Columns)
                        {
                            headerRow.CreateCell(column.Index).SetCellValue(column.HeaderText);
                            headerRow.GetCell(column.Index).CellStyle = headStyle;

                            //设置列宽
                            //sheet.SetColumnWidth(column.Index, (arrColWidth[column.Index] + 1) * 256);
                        }
                        // headerRow.Dispose();
                    }
                    #endregion

                    rowIndex = 2;
                }
                #endregion

                #region 填充内容
                IRow dataRow = sheet.CreateRow(rowIndex);
                if (row.Index > 0)
                {
                    foreach (DataGridViewColumn column in myDgv.Columns)
                    {
                        ICell newCell = dataRow.CreateCell(column.Index);

                        string drValue = myDgv[column.Index, row.Index - 1].Value.ToString();

                        switch (column.ValueType.ToString())
                        {
                            case "System.String"://字符串类型
                                newCell.SetCellValue(drValue);
                                break;
                            case "System.DateTime"://日期类型
                                System.DateTime dateV;
                                System.DateTime.TryParse(drValue, out dateV);
                                newCell.SetCellValue(dateV);

                                newCell.CellStyle = cellStyle;//格式化显示
                                break;
                            case "System.Boolean"://布尔型
                                bool boolV = false;
                                bool.TryParse(drValue, out boolV);
                                newCell.SetCellValue(boolV);
                                break;
                            case "System.Int16"://整型
                            case "System.Int32":
                            case "System.Int64":
                            case "System.Byte":
                                int intV = 0;
                                int.TryParse(drValue, out intV);
                                newCell.SetCellValue(intV);
                                break;
                            case "System.Decimal"://浮点型
                            case "System.Double":
                                double doubV = 0;
                                double.TryParse(drValue, out doubV);
                                newCell.SetCellValue(doubV);
                                break;
                            case "System.DBNull"://空值处理
                                newCell.SetCellValue("");
                                break;
                            default:
                                newCell.SetCellValue("");
                                break;
                        }

                    }
                }
                else
                { rowIndex--; }
                #endregion

                rowIndex++;
            }

            MemoryStream ms = new MemoryStream();
            workbook.Write(ms);
            ms.Flush();
#if New_NPOI
            workbook.Close();
#endif
            return ms;          
        }
        #endregion
    }

    /// <summary>
    /// excel文件后缀格式
    /// </summary>
    enum ExcelFileSuffixType
    {
        /// <summary>
        /// Excel 2007及以上版本支持
        /// </summary>
        xls,
        /// <summary>
        /// Excel 2003及以上版本兼容支持
        /// </summary>
        xlsx
    }

注，测试NPOI版本为：2.5.1.0，包含的文件及依赖：

 

------------恢复内容开始------------

 /// <summary>
    /// NPOIExcel帮助类
    /// </summary>
    public class NPOIExcelHelper
    {
        /// <summary>
        /// DataTable导出到Excel文件
        /// </summary>
        /// <param name="dtSource">源DataTable</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strFileName">保存位置</param>
        public static void DataTableToExcel(DataTable dtSource, string strHeaderText, string strFileName)
        {
            ExcelFileSuffixType suffix = default(ExcelFileSuffixType);
            if (strFileName.IndexOf(".xlsx") > 0) // 2007版本
                suffix = ExcelFileSuffixType.xlsx;
            else if (strFileName.IndexOf(".xls") > 0) // 2003版本
                suffix = ExcelFileSuffixType.xls;

            using (MemoryStream ms = DataTableToExcelStream(dtSource, strHeaderText, suffix))
            {
                using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write))
                {
                    byte[] data = ms.ToArray();
                    fs.Write(data, 0, data.Length);
                    fs.Flush();
                }
            }
        }

        /// <summary>
        /// DataGridView导出到Excel文件
        /// </summary>
        /// <param name="dtSource">源DataTGridview</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strFileName">保存位置</param>
        public static void DataGridViewToExcel(DataGridView myDgv, string strHeaderText, string strFileName)
        {
            ExcelFileSuffixType suffix = default(ExcelFileSuffixType);
            if (strFileName.IndexOf(".xlsx") > 0) // 2007版本
                suffix = ExcelFileSuffixType.xlsx;
            else if (strFileName.IndexOf(".xls") > 0) // 2003版本
                suffix = ExcelFileSuffixType.xls;

            using (MemoryStream ms = DataGridViewToExcelStream(myDgv, strHeaderText, suffix))
            {
                using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write))
                {
                    byte[] data = ms.ToArray();
                    fs.Write(data, 0, data.Length);
                    fs.Flush();
                }
            }
        }

        /// <summary>
        /// 将excel文件导入至DataTable
        /// </summary>
        /// <param name="strFileName">excel文件全路径</param>
        /// <returns></returns>
        public static DataTable ExcelToDataTable(string strFileName)
        {
            DataTable dt = new DataTable();

            IWorkbook workbook = null;

            using (FileStream file = new FileStream(strFileName, FileMode.Open, FileAccess.Read))
            {
#if New_NPOI
                if (strFileName.IndexOf(".xlsx") > 0) // 2007版本
                    workbook = new XSSFWorkbook(file);
                else if (strFileName.IndexOf(".xls") > 0) // 2003版本
                    workbook = new HSSFWorkbook(file);
#endif
#if Old_NPOI
                workbook = new HSSFWorkbook(file);
#endif
            }

            ISheet sheet = workbook.GetSheetAt(0);
            System.Collections.IEnumerator rows = sheet.GetRowEnumerator();

            IRow headerRow = sheet.GetRow(0);
            int cellCount = headerRow.LastCellNum;

            for (int j = 0; j < cellCount; j++)
            {
                ICell cell = headerRow.GetCell(j);
                dt.Columns.Add(cell.ToString());
            }

            for (int i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum; i++)
            {
                IRow row = sheet.GetRow(i);
                DataRow dataRow = dt.NewRow();

                for (int j = row.FirstCellNum; j < cellCount; j++)
                {
                    if (row.GetCell(j) != null)
                        dataRow[j] = row.GetCell(j).ToString();
                }

                dt.Rows.Add(dataRow);
            }

            return dt;
        }

        #region private
        /// <summary>
        /// DataTable导出到Excel的MemoryStream
        /// </summary>
        /// <param name="dtSource">源DataTable</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strHeaderText">excel文件后缀类型</param>
        private static MemoryStream DataTableToExcelStream(DataTable dtSource, string strHeaderText, ExcelFileSuffixType suffix)
        {
            ISheet sheet = null;
            IWorkbook workbook = null;
            ICellStyle cellStyle = null;
            IDataFormat dataFormat = null;

#if New_NPOI
            if (suffix == ExcelFileSuffixType.xls)
                workbook = new HSSFWorkbook();
            else if (suffix == ExcelFileSuffixType.xlsx)
                workbook = new XSSFWorkbook();
#endif
#if Old_NPOI
            workbook = new HSSFWorkbook();
#endif

            sheet = workbook.CreateSheet();

            cellStyle = workbook.CreateCellStyle();
            dataFormat = workbook.CreateDataFormat();
            cellStyle.DataFormat = dataFormat.GetFormat("yyyy-mm-dd");

            //取得列宽
            int[] arrColWidth = new int[dtSource.Columns.Count];
            foreach (DataColumn item in dtSource.Columns)
            {
                arrColWidth[item.Ordinal] = Encoding.GetEncoding(936).GetBytes(item.ColumnName.ToString()).Length;
            }
            for (int i = 0; i < dtSource.Rows.Count; i++)
            {
                for (int j = 0; j < dtSource.Columns.Count; j++)
                {
                    int intTemp = Encoding.GetEncoding(936).GetBytes(dtSource.Rows[i][j].ToString()).Length;
                    if (intTemp > arrColWidth[j])
                    {
                        arrColWidth[j] = intTemp;
                    }
                }
            }
            int rowIndex = 0;
            foreach (DataRow row in dtSource.Rows)
            {
                #region 新建表，填充表头，填充列头，样式
                if (rowIndex == 65535 || rowIndex == 0)
                {
                    if (rowIndex != 0)
                    {
                        sheet = workbook.CreateSheet();
                    }

                    #region 表头及样式
                    {
                        IRow headerRow = sheet.CreateRow(0);
                        headerRow.HeightInPoints = 25;
                        headerRow.CreateCell(0).SetCellValue(strHeaderText);

                        ICellStyle headStyle = workbook.CreateCellStyle();
                        //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                        IFont font = workbook.CreateFont();
                        font.FontHeightInPoints = 20;
#if New_NPOI
                        font.IsBold = true;
#endif
#if Old_NPOI
                        font.Boldweight = 700;
#endif
                        headStyle.SetFont(font);
                        headerRow.GetCell(0).CellStyle = headStyle;
                        //sheet.AddMergedRegion(new Region(0, 0, 0, dtSource.Columns.Count - 1));
                        //headerRow.Dispose();
                    }
                    #endregion

                    #region 列头及样式
                    {
                        IRow headerRow = sheet.CreateRow(1);
                        ICellStyle headStyle = workbook.CreateCellStyle();
                        //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                        IFont font = workbook.CreateFont();
                        font.FontHeightInPoints = 10;
#if New_NPOI
                        font.IsBold = true;
#endif
#if Old_NPOI
                        font.Boldweight = 700;
#endif
                        headStyle.SetFont(font);
                        foreach (DataColumn column in dtSource.Columns)
                        {
                            headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
                            headerRow.GetCell(column.Ordinal).CellStyle = headStyle;

                            //设置列宽
                            //  sheet.SetColumnWidth(column.Ordinal, (arrColWidth[column.Ordinal] + 1) * 256); 
                        }
                        // headerRow.Dispose();
                    }
                    #endregion

                    rowIndex = 2;
                }
                #endregion

                #region 填充内容
                IRow dataRow = sheet.CreateRow(rowIndex);
                foreach (DataColumn column in dtSource.Columns)
                {
                    ICell newCell = dataRow.CreateCell(column.Ordinal);

                    string drValue = row[column].ToString();

                    switch (column.DataType.ToString())
                    {
                        case "System.String"://字符串类型
                            if (drValue.Length > 30000)
                                drValue = drValue.Substring(0, 30000);
                            newCell.SetCellValue(drValue);
                            break;
                        case "System.DateTime"://日期类型
                            System.DateTime dateV;
                            System.DateTime.TryParse(drValue, out dateV);
                            newCell.SetCellValue(dateV);

                            newCell.CellStyle = cellStyle;//格式化显示
                            break;
                        case "System.Boolean"://布尔型
                            bool boolV = false;
                            bool.TryParse(drValue, out boolV);
                            newCell.SetCellValue(boolV);
                            break;
                        case "System.Int16"://整型
                        case "System.Int32":
                        case "System.Int64":
                        case "System.Byte":
                            int intV = 0;
                            int.TryParse(drValue, out intV);
                            newCell.SetCellValue(intV);
                            break;
                        case "System.Decimal"://浮点型
                        case "System.Double":
                            double doubV = 0;
                            double.TryParse(drValue, out doubV);
                            newCell.SetCellValue(doubV);
                            break;
                        case "System.DBNull"://空值处理
                            newCell.SetCellValue("");
                            break;
                        default:
                            newCell.SetCellValue("");
                            break;
                    }

                }
                #endregion

                rowIndex++;
            }
            using (MemoryStream ms = new MemoryStream())
            {
                workbook.Write(ms);
                ms.Flush();
#if New_NPOI
                workbook.Close();
#endif
                return ms;
            }
        }

        /// <summary>
        /// DataTable导出到Excel的MemoryStream
        /// </summary>
        /// <param name="myDgv">源DataTable</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strHeaderText">excel文件后缀类型</param>
        private static MemoryStream DataGridViewToExcelStream(DataGridView myDgv, string strHeaderText, ExcelFileSuffixType suffix)
        {
            ISheet sheet = null;
            IWorkbook workbook = null;
            ICellStyle cellStyle = null;
            IDataFormat dataFormat = null;

#if New_NPOI
            if (suffix == ExcelFileSuffixType.xls)
                workbook = new HSSFWorkbook();
            else if (suffix == ExcelFileSuffixType.xlsx)
                workbook = new XSSFWorkbook();
#endif
#if Old_NPOI
            workbook = new HSSFWorkbook();
#endif
            sheet = workbook.CreateSheet();

            cellStyle = workbook.CreateCellStyle();
            dataFormat = workbook.CreateDataFormat();
            cellStyle.DataFormat = dataFormat.GetFormat("yyyy-mm-dd");

            //取得列宽
            int[] arrColWidth = new int[myDgv.Columns.Count];
            foreach (DataGridViewColumn item in myDgv.Columns)
            {
                arrColWidth[item.Index] = Encoding.GetEncoding(936).GetBytes(item.HeaderText.ToString()).Length;
            }
            for (int i = 0; i < myDgv.Rows.Count; i++)
            {
                for (int j = 0; j < myDgv.Columns.Count; j++)
                {
                    int intTemp = Encoding.GetEncoding(936).GetBytes(myDgv.Rows[i].Cells[j].ToString()).Length;
                    if (intTemp > arrColWidth[j])
                    {
                        arrColWidth[j] = intTemp;
                    }
                }
            }
            int rowIndex = 0;
            foreach (DataGridViewRow row in myDgv.Rows)
            {
                #region 新建表，填充表头，填充列头，样式
                if (rowIndex == 65535 || rowIndex == 0)
                {
                    if (rowIndex != 0)
                    {
                        sheet = workbook.CreateSheet();
                    }

                    #region 表头及样式
                    {
                        IRow headerRow = sheet.CreateRow(0);
                        headerRow.HeightInPoints = 25;
                        headerRow.CreateCell(0).SetCellValue(strHeaderText);

                        ICellStyle headStyle = workbook.CreateCellStyle();
                        //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                        IFont font = workbook.CreateFont();
                        font.FontHeightInPoints = 20;
#if New_NPOI
                        font.IsBold = true;
#endif
#if Old_NPOI
                        font.Boldweight = 700;
#endif
                        headStyle.SetFont(font);
                        headerRow.GetCell(0).CellStyle = headStyle;
                        // sheet.AddMergedRegion(new Region(0, 0, 0, dtSource.Columns.Count - 1));
                        //headerRow.Dispose();
                    }
                    #endregion


                    #region 列头及样式
                    {
                        IRow headerRow = sheet.CreateRow(1);
                        ICellStyle headStyle = workbook.CreateCellStyle();
                        //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                        IFont font = workbook.CreateFont();
                        font.FontHeightInPoints = 10;
#if New_NPOI
                        font.IsBold = true;
#endif
#if Old_NPOI
                        font.Boldweight = 700;
#endif
                        headStyle.SetFont(font);
                        foreach (DataGridViewColumn column in myDgv.Columns)
                        {
                            headerRow.CreateCell(column.Index).SetCellValue(column.HeaderText);
                            headerRow.GetCell(column.Index).CellStyle = headStyle;

                            //设置列宽
                            //sheet.SetColumnWidth(column.Index, (arrColWidth[column.Index] + 1) * 256);
                        }
                        // headerRow.Dispose();
                    }
                    #endregion

                    rowIndex = 2;
                }
                #endregion

                #region 填充内容
                IRow dataRow = sheet.CreateRow(rowIndex);
                if (row.Index > 0)
                {
                    foreach (DataGridViewColumn column in myDgv.Columns)
                    {
                        ICell newCell = dataRow.CreateCell(column.Index);

                        string drValue = myDgv[column.Index, row.Index - 1].Value.ToString();

                        switch (column.ValueType.ToString())
                        {
                            case "System.String"://字符串类型
                                newCell.SetCellValue(drValue);
                                break;
                            case "System.DateTime"://日期类型
                                System.DateTime dateV;
                                System.DateTime.TryParse(drValue, out dateV);
                                newCell.SetCellValue(dateV);

                                newCell.CellStyle = cellStyle;//格式化显示
                                break;
                            case "System.Boolean"://布尔型
                                bool boolV = false;
                                bool.TryParse(drValue, out boolV);
                                newCell.SetCellValue(boolV);
                                break;
                            case "System.Int16"://整型
                            case "System.Int32":
                            case "System.Int64":
                            case "System.Byte":
                                int intV = 0;
                                int.TryParse(drValue, out intV);
                                newCell.SetCellValue(intV);
                                break;
                            case "System.Decimal"://浮点型
                            case "System.Double":
                                double doubV = 0;
                                double.TryParse(drValue, out doubV);
                                newCell.SetCellValue(doubV);
                                break;
                            case "System.DBNull"://空值处理
                                newCell.SetCellValue("");
                                break;
                            default:
                                newCell.SetCellValue("");
                                break;
                        }

                    }
                }
                else
                { rowIndex--; }
                #endregion

                rowIndex++;
            }
            using (MemoryStream ms = new MemoryStream())
            {
                workbook.Write(ms);
                ms.Flush();
#if New_NPOI
                workbook.Close();
#endif
                return ms;
            }
        }
        #endregion
    }

    /// <summary>
    /// excel文件后缀格式
    /// </summary>
    enum ExcelFileSuffixType
    {
        /// <summary>
        /// Excel 2007及以上版本支持
        /// </summary>
        xls,
        /// <summary>
        /// Excel 2003及以上版本兼容支持
        /// </summary>
        xlsx
    }

注，测试NPOI版本为：2.5.1.0，包含的文件及依赖：

 

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