NPOIHelper

public class NPOIHelper
    {
        public static MemoryStream Export(DataTable dtSource, string strHeaderText, string strFileName)
        {

            string fileExt = Path.GetExtension(strFileName).ToLower();
            IWorkbook workbook;
            if (fileExt == ".xlsx")
                workbook = new XSSFWorkbook();
            else
                workbook = new HSSFWorkbook();
            ISheet sheet = workbook.CreateSheet();

            //#region 右击文件 属性信息     //不支持2007
            //{
            //    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 = DateTime.Now;
            //    workbook.SummaryInformation = si;
            //}
            //#endregion

            var dateStyle = workbook.CreateCellStyle();
            var format = workbook.CreateDataFormat();
            dateStyle.DataFormat = format.GetFormat("yyyy-MM-dd HH:mm:ss");

            //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
                    {
                        var headerRow = sheet.CreateRow(0);
                        headerRow.HeightInPoints = 25;
                        headerRow.CreateCell(0).SetCellValue(strHeaderText);

                        var headStyle = workbook.CreateCellStyle();
                        headStyle.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center;
                        var font = workbook.CreateFont();
                        font.FontHeightInPoints = 20;
                        font.Boldweight = 700;
                        headStyle.SetFont(font);
                        headerRow.GetCell(0).CellStyle = headStyle;
                        sheet.AddMergedRegion(new CellRangeAddress(0, 0, 0, dtSource.Columns.Count - 1));
                        //headerRow.Dispose();
                    }
                    #endregion


                    #region 列头及样式
                    {
                        var headerRow = sheet.CreateRow(1);
                        var headStyle = workbook.CreateCellStyle();
                        headStyle.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center;
                        var font = workbook.CreateFont();
                        font.FontHeightInPoints = 10;
                        font.Boldweight = 700;
                        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
                var dataRow = sheet.CreateRow(rowIndex);
                foreach (DataColumn column in dtSource.Columns)
                {
                    var newCell = dataRow.CreateCell(column.Ordinal);
                    string drValue = row[column].ToString();
                    switch (column.DataType.ToString())
                    {
                        case "System.Object":
                        case "System.String"://字符串类型
                            newCell.SetCellValue(drValue);
                            newCell.CellStyle = dateStyle;
                            break;
                        case "System.DateTime"://日期类型
                            DateTime dateV;
                            if (DateTime.TryParse(drValue, out dateV))
                            {
                                newCell.SetCellValue(dateV);
                            }
                            else
                            {
                                //newCell.SetCellValue("");
                            }
                            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 (NpoiMemoryStream ms = new NpoiMemoryStream())
            {
                ms.AllowClose = false;
                workbook.Write(ms);
                ms.Flush();
                ms.Position = 0;
                //ms.AllowClose = true;

                //sheet.CloneSheet(workbook);
                //workbook.Dispose();//一般只用写这一个就OK了，他会遍历并释放所有资源，但当前版本有问题所以只释放sheet
                return ms;
            }
        }

        public static MemoryStream Export(List<MergeModel> list, string strHeaderText, string strFileName)
        {

            string fileExt = Path.GetExtension(strFileName).ToLower();
            IWorkbook workbook;
            if (fileExt == ".xlsx")
                workbook = new XSSFWorkbook();
            else
                workbook = new HSSFWorkbook();

            for (int table_index = 0; table_index < list.Count; table_index++)
            {
                var dtSource = list[table_index].dt;
                ISheet sheet = workbook.CreateSheet(list[table_index].sheetname);

                //#region 右击文件 属性信息     //不支持2007
                //{
                //    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 = DateTime.Now;
                //    workbook.SummaryInformation = si;
                //}
                //#endregion

                var dateStyle = workbook.CreateCellStyle();
                var format = workbook.CreateDataFormat();
                dateStyle.DataFormat = format.GetFormat("yyyy-MM-dd HH:mm:ss");

                //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(list[table_index].sheetname);
                        }

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

                            var headStyle = workbook.CreateCellStyle();
                            headStyle.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center;
                            var font = workbook.CreateFont();
                            font.FontHeightInPoints = 20;
                            font.Boldweight = 700;
                            headStyle.SetFont(font);
                            headerRow.GetCell(0).CellStyle = headStyle;
                            sheet.AddMergedRegion(new CellRangeAddress(0, 0, 0, dtSource.Columns.Count - 1));
                            //headerRow.Dispose();
                        }
                        #endregion


                        #region 列头及样式
                        {
                            var headerRow = sheet.CreateRow(1);
                            var headStyle = workbook.CreateCellStyle();
                            headStyle.Alignment = NPOI.SS.UserModel.HorizontalAlignment.Center;
                            var font = workbook.CreateFont();
                            font.FontHeightInPoints = 10;
                            font.Boldweight = 700;
                            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
                    var dataRow = sheet.CreateRow(rowIndex);
                    foreach (DataColumn column in dtSource.Columns)
                    {
                        var newCell = dataRow.CreateCell(column.Ordinal);
                        string drValue = row[column].ToString();
                        switch (column.DataType.ToString())
                        {
                            case "System.String"://字符串类型
                                newCell.SetCellValue(drValue);
                                newCell.CellStyle = dateStyle;
                                break;
                            case "System.DateTime"://日期类型
                                DateTime dateV;
                                if (DateTime.TryParse(drValue, out dateV))
                                {
                                    newCell.SetCellValue(dateV);
                                }
                                else
                                {
                                    //newCell.SetCellValue("");
                                }
                                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 (NpoiMemoryStream ms = new NpoiMemoryStream())
            {
                ms.AllowClose = false;
                workbook.Write(ms);
                ms.Flush();
                ms.Position = 0;
                //ms.AllowClose = true;

                //sheet.CloneSheet(workbook);
                //workbook.Dispose();//一般只用写这一个就OK了，他会遍历并释放所有资源，但当前版本有问题所以只释放sheet
                return ms;
            }
        }
        /// <summary>
        /// 用于Web导出
        /// </summary>
        /// <param name="dtSource">源DataTable</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strFileName">文件名</param>
        public static void ExportByWeb(DataTable dtSource, string strHeaderText, string strFileName, HttpContext context = null)
        {
            if (dtSource == null || dtSource.Rows.Count <= 0) return;
            HttpContext curContext = HttpContext.Current;
            if (context != null) curContext = context;
            // 设置编码和附件格式
            curContext.Response.ContentType = "application/vnd.ms-excel";
            //curContext.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
            curContext.Response.ContentEncoding = Encoding.UTF8;
            curContext.Response.Charset = "";
            curContext.Response.AppendHeader("Content-Disposition",
                "attachment;filename=" + HttpUtility.UrlEncode(strFileName, Encoding.UTF8));
            //避免xlsx出错
            var ms = Export(dtSource, strHeaderText, strFileName);
            byte[] fileBuffer = new byte[ms.Length];
            ms.Read(fileBuffer, 0, (int)ms.Length);
            ms.Close();
            ms.Dispose();
            curContext.Response.BinaryWrite(fileBuffer);
            curContext.Response.Output.Flush();
            curContext.Response.End();
        }

        /// <summary>
        /// 用于Web导出
        /// </summary>
        /// <param name="dtSource">源DataTable</param>
        /// <param name="strHeaderText">表头文本</param>
        /// <param name="strFileName">文件名</param>
        public static void ExportByWeb(List<MergeModel> dtSource, string strHeaderText, string strFileName, HttpContext context = null)
        {
            HttpContext curContext = HttpContext.Current;
            if (context != null) curContext = context;
            // 设置编码和附件格式
            curContext.Response.ContentType = "application/vnd.ms-excel";
            //curContext.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
            curContext.Response.ContentEncoding = Encoding.UTF8;
            curContext.Response.Charset = "";
            curContext.Response.AppendHeader("Content-Disposition",
                "attachment;filename=" + HttpUtility.UrlEncode(strFileName, Encoding.UTF8));
            //避免xlsx出错
            var ms = Export(dtSource, strHeaderText, strFileName);
            byte[] fileBuffer = new byte[ms.Length];
            ms.Read(fileBuffer, 0, (int)ms.Length);
            ms.Close();
            ms.Dispose();
            curContext.Response.BinaryWrite(fileBuffer);
            curContext.Response.Output.Flush();
            curContext.Response.End();
        }

        /// <summary>
        /// 实体列表转换成DataTable
        /// </summary>
        /// <typeparam name="T">实体</typeparam>
        /// <param name="list"> 实体列表</param>
        /// <returns></returns>
        public static DataTable ListToDataTable<T>(IList<T> list)
            where T : class
        {
            if (list == null || list.Count <= 0)
            {
                return null;
            }
            DataTable dt = new DataTable(typeof(T).Name);
            DataColumn column;
            DataRow row;

            PropertyInfo[] myPropertyInfo = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);

            int length = myPropertyInfo.Length;
            bool createColumn = true;

            foreach (T t in list)
            {
                if (t == null)
                {
                    continue;
                }

                row = dt.NewRow();
                for (int i = 0; i < length; i++)
                {
                    PropertyInfo pi = myPropertyInfo[i];
                    string name = pi.Name;
                    if (createColumn)
                    {
                        try
                        {
                            column = new DataColumn(name, pi.PropertyType);
                            dt.Columns.Add(column);
                        }
                        catch (Exception ex)
                        {
                            var n = "";
                        }
                    }

                    row[name] = pi.GetValue(t, null);
                }

                if (createColumn)
                {
                    createColumn = false;
                }

                dt.Rows.Add(row);
            }
            return dt;

        }

        //新建类 重写Npoi流方法 (生成.xlsx 必须使用这个转换 否则无法打开，目前只有此方法可解决.xlsx问题)
        public class NpoiMemoryStream : MemoryStream
        {
            public NpoiMemoryStream()
            {
                AllowClose = true;
            }

            public bool AllowClose { get; set; }

            public override void Close()
            {
                if (AllowClose)
                    base.Close();
            }
        }

        public class MergeModel
        {
            /// <summary>
            /// Sheet名称
            /// </summary>
            public string sheetname { get; set; }
            /// <summary>
            /// 数据
            /// </summary>
            public DataTable dt { get; set; }
        }
    }