NPOI DataSet导出excel

        /// <summary>
        /// DataSet导出到Excel的MemoryStream
        /// </summary>
        /// <param name="dtSource">源DataSet</param>
        public static MemoryStream DataSetToExcel(DataSet ds)
        {
            XSSFWorkbook workbook = new XSSFWorkbook();
            for (int k = 0; k < ds.Tables.Count; k++)
            {
                //   HSSFSheet sheet = (HSSFSheet)workbook.CreateSheet();
                XSSFSheet sheet = (XSSFSheet)workbook.CreateSheet(ds.Tables[k].TableName.ToString());

                #region 右击文件 属性信息
                {
                    DocumentSummaryInformation dsi = PropertySetFactory.CreateDocumentSummaryInformation();
                    dsi.Company = "NPOI";

                    // workbook.DocumentSummaryInformation = dsi;

                    SummaryInformation si = PropertySetFactory.CreateSummaryInformation();
                    si.Author = "文件作者信息"; //填加xls文件作者信息
                    si.ApplicationName = "创建程序信息"; //填加xls文件创建程序信息
                    si.LastAuthor = "最后保存者信息"; //填加xls文件最后保存者信息
                    si.Comments = "作者信息"; //填加xls文件作者信息
                    si.Title = "标题信息"; //填加xls文件标题信息
                    si.Subject = "主题信息";//填加文件主题信息
                    si.CreateDateTime = System.DateTime.Now;
                    // workbook.SummaryInformation = si;
                }
                #endregion

                XSSFCellStyle dateStyle = (XSSFCellStyle)workbook.CreateCellStyle();
                XSSFDataFormat format = (XSSFDataFormat)workbook.CreateDataFormat();
                dateStyle.DataFormat = format.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 ds.Tables[k].Rows)
                {
                    #region 新建表，填充表头，填充列头，样式
                    if (rowIndex == 0)
                    {
                        //if (rowIndex != 0)
                        //{
                        //    sheet = (XSSFSheet)workbook.CreateSheet();
                        //}

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

                            //HSSFCellStyle headStyle = (HSSFCellStyle)workbook.CreateCellStyle();
                            ////  headStyle.Alignment = CellHorizontalAlignment.CENTER;
                            //HSSFFont font = (HSSFFont)workbook.CreateFont();
                            //font.FontHeightInPoints = 20;
                            //font.Boldweight = 700;
                            //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
                        {
                            XSSFRow headerRow = (XSSFRow)sheet.CreateRow(0);
                            XSSFCellStyle headStyle = (XSSFCellStyle)workbook.CreateCellStyle();
                            //headStyle.Alignment = CellHorizontalAlignment.CENTER;
                            XSSFFont font = (XSSFFont)workbook.CreateFont();
                            font.FontHeightInPoints = 10;
                            font.Boldweight = 700;
                            headStyle.SetFont(font);
                            foreach (DataColumn column in ds.Tables[k].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 = 1;
                    }
                    #endregion


                    #region 填充内容
                    XSSFRow dataRow = (XSSFRow)sheet.CreateRow(rowIndex);
                    foreach (DataColumn column in ds.Tables[k].Columns)
                    {
                        XSSFCell newCell = (XSSFCell)dataRow.CreateCell(column.Ordinal);

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

                        switch (column.DataType.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 = dateStyle;//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();
                return ms;
            }
        }

        /// <summary>
        /// DataSet导出到Excel文件
        /// </summary>
        /// <param name="dtSource">源DataSet</param>
        /// <param name="strFileName">保存位置</param>
        public static void DataSetToExcel(DataSet dtSource, string strFileName)
        {
            using (MemoryStream ms = DataSetToExcel(dtSource ))
            {
                using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write))
                {
                    byte[] data = ms.ToArray();
                    fs.Write(data, 0, data.Length);
                    fs.Flush();
                }
            }
        }