NPOI的总结

NPOI，顾名思义，就是POI的.NET版本。那POI又是什么呢？POI是一套用Java写成的库，能够帮助开发者在没有安装微软Office的情况下读写Office的文件。

支持的文件格式包括xls, doc, ppt等。

官方网站：http://npoi.codeplex.com/

nuget直接获取使用

一、NPOI生成Excel

            //创建工作薄            var workbook = new HSSFWorkbook();            //创建表            var table = workbook.CreateSheet("joye.net");            //模拟20行20列数据            for (var i = 0; i < 20; i++)            {                var row = table.CreateRow(i);                for (int j = 0; j < 20; j++)                {                    var cell = row.CreateCell(j);                    cell.SetCellValue(j);                }            }            //打开xls文件，如没有则创建，如存在则在创建是不要打开该文件            using (var fs = File.OpenWrite(@"c:/joye.net.xls"))            {                workbook.Write(fs);   //向打开的这个xls文件中写入mySheet表并保存。                Console.WriteLine("生成成功");            }

二、NPOI读取Excel

using (var fs = File.OpenRead(@"c:/joye.net.xls"))             {                //把xls文件中的数据写入workbook1中                var workbook1 = new HSSFWorkbook(fs);                for (var i = 0; i < workbook1.NumberOfSheets; i++)                {                    var sheet = workbook1.GetSheetAt(i);                    for (var j = 0; j <= sheet.LastRowNum; j++)                    {                           //读取当前行数据                        var row = sheet.GetRow(j);                        if (row != null)                        {                            for (var k = 0; k <= row.LastCellNum; k++)                            {   //当前表格                                var cell = row.GetCell(k);                                if (cell != null)                                {                                    Console.Write(cell.ToString() + "  ");                                }                            }                        }                        Console.WriteLine();                    }                }            }

读出的结果

 三、简单学习

/// <summary>        ///  组装workbook.        /// </summary>        /// <param name="dt">dataTable资源</param>        /// <param name="columnHeader">表头</param>        /// <returns></returns>        public static HSSFWorkbook BuildWorkbook1(DataTable dt, string columnHeader = "")        {            var workbook = new HSSFWorkbook();            ISheet sheet = workbook.CreateSheet(string.IsNullOrWhiteSpace(dt.TableName) ? "Sheet1" : dt.TableName);            #region 文件属性信息            {                var dsi = PropertySetFactory.CreateDocumentSummaryInformation();                dsi.Company = "NPOI";                workbook.DocumentSummaryInformation = dsi;                SummaryInformation si = PropertySetFactory.CreateSummaryInformation();                si.Author = "文件作者信息";                si.ApplicationName = "创建程序信息";                si.LastAuthor = "最后保存者信息";                si.Comments = "作者信息";                si.Title = "标题信息";                si.Subject = "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");            //取得列宽            var arrColWidth = new int[dt.Columns.Count];            foreach (DataColumn item in dt.Columns)            {                arrColWidth[item.Ordinal] = Encoding.GetEncoding(936).GetBytes(item.ColumnName.ToString()).Length;            }            for (var i = 0; i < dt.Rows.Count; i++)            {                for (var j = 0; j < dt.Columns.Count; j++)                {                    int intTemp = Encoding.GetEncoding(936).GetBytes(dt.Rows[i][j].ToString()).Length;                    if (intTemp > arrColWidth[j])                    {                        arrColWidth[j] = intTemp;                    }                }            }            int rowIndex = 0;            foreach (DataRow row in dt.Rows)            {                #region 表头 列头                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(columnHeader);                        //CellStyle                        ICellStyle headStyle = workbook.CreateCellStyle();                        headStyle.Alignment = HorizontalAlignment.Center;// 左右居中                            headStyle.VerticalAlignment = VerticalAlignment.Center;// 上下居中                         // 设置单元格的背景颜色（单元格的样式会覆盖列或行的样式）                            headStyle.FillForegroundColor = (short)11;                        //定义font                        IFont font = workbook.CreateFont();                        font.FontHeightInPoints = 20;                        font.Boldweight = 700;                        headStyle.SetFont(font);                        headerRow.GetCell(0).CellStyle = headStyle;                        sheet.AddMergedRegion(new CellRangeAddress(0, 0, 0, dt.Columns.Count - 1));                    }                    #endregion                    #region 列头及样式                    {                        var headerRow = sheet.CreateRow(1);                        //CellStyle                        ICellStyle headStyle = workbook.CreateCellStyle();                        headStyle.Alignment = HorizontalAlignment.Center;// 左右居中                            headStyle.VerticalAlignment = VerticalAlignment.Center;// 上下居中                         //定义font                        IFont font = workbook.CreateFont();                        font.FontHeightInPoints = 10;                        font.Boldweight = 700;                        headStyle.SetFont(font);                        foreach (DataColumn column in dt.Columns)                        {                            headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);                            headerRow.GetCell(column.Ordinal).CellStyle = headStyle;                            sheet.SetColumnWidth(column.Ordinal, (arrColWidth[column.Ordinal] + 1) * 256);                        }                    }                    #endregion                    if (columnHeader != "")                    {                        //header row                        IRow row0 = sheet.CreateRow(0);                        for (int i = 0; i < dt.Columns.Count; i++)                        {                            ICell cell = row0.CreateCell(i, CellType.String);                            cell.SetCellValue(dt.Columns[i].ColumnName);                        }                    }                    rowIndex = 2;                }                #endregion                #region 内容                var dataRow = sheet.CreateRow(rowIndex);                foreach (DataColumn column in dt.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);                            break;                        case "System.DateTime"://日期类型                            DateTime dateV;                            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++;            }            //自动列宽            for (int i = 0; i <= dt.Columns.Count; i++)                sheet.AutoSizeColumn(i, true);            return workbook;        }

            var dt = new DataTable();             //模拟20行20列数据            for (var i = 0; i < 3; i++)            {                dt.Columns.Add(i.ToString());            }            for (var j = 0; j < 65537; j++)            {                dt.Rows.Add(new object[] { 0 ,1,2 });            }            var newBook = BuildWorkbook(dt);            using (var fs = File.OpenWrite(@"c:/joye.net1.xls"))            {                newBook.Write(fs);                Console.WriteLine("生成成功");            }

四、NPOI导出Excel 65536问题

        public static HSSFWorkbook BuildWorkbook(DataTable dt)        {            var book = new HSSFWorkbook();              ISheet sheet = book.CreateSheet("Sheet1");            //Data Rows            for (int i = 0; i < dt.Rows.Count; i++)            {                IRow drow = sheet.CreateRow(i);                for (int j = 0; j < dt.Columns.Count; j++)                {                    ICell cell = drow.CreateCell(j, CellType.String);                    cell.SetCellValue(dt.Rows[i][j].ToString());                }            }            //自动列宽            for (int i = 0; i <= dt.Columns.Count; i++)                sheet.AutoSizeColumn(i, true);            return book;        }

NPOI导出Excel超过65536会报异常，原来是由于NPOI这个动态库导致的，然后看了下版本，发现是1.2.5。然后百度了下，发现这个版本的NPOI只支持office2003，二office2003最多支持65536行

解决方式：

1、只是在插入数据的时候，加个判断，如果数据条数大于65536时，就在创建一个sheet

        //65536判断处理        public static HSSFWorkbook BuildWorkbook(DataTable dt)        {            var book = new HSSFWorkbook();            ISheet sheet1 = book.CreateSheet("Sheet1");            ISheet sheet2 = book.CreateSheet("Sheet2");            //填充数据            for (int i = 0; i < dt.Rows.Count; i++)            {                if (i < 65536)                {                    IRow drow = sheet1.CreateRow(i);                    for (int j = 0; j < dt.Columns.Count; j++)                    {                        ICell cell = drow.CreateCell(j, CellType.String);                        cell.SetCellValue(dt.Rows[i][j].ToString());                    }                }                if (i >= 65536)                {                    IRow drow = sheet2.CreateRow(i - 65536);                    for (int j = 0; j < dt.Columns.Count; j++)                    {                        ICell cell = drow.CreateCell(j, CellType.String);                        cell.SetCellValue(dt.Rows[i][j].ToString());                    }                }            }            //自动列宽            for (int i = 0; i <= dt.Columns.Count; i++)            {                sheet1.AutoSizeColumn(i, true);                sheet2.AutoSizeColumn(i, true);            }            return book;        }

2、考虑使用高版本Office，使用用对象支持高版本的NPOI

        //高版本        public static XSSFWorkbook BuildWorkbook(DataTable dt)        {            var book = new XSSFWorkbook();            ISheet sheet = book.CreateSheet("Sheet1");            //Data Rows            for (int i = 0; i < dt.Rows.Count; i++)            {                IRow drow = sheet.CreateRow(i);                for (int j = 0; j < dt.Columns.Count; j++)                {                    ICell cell = drow.CreateCell(j, CellType.String);                    cell.SetCellValue(dt.Rows[i][j].ToString());                }            }            //自动列宽            for (int i = 0; i <= dt.Columns.Count; i++)                sheet.AutoSizeColumn(i, true);            return book;        }

五、web开发中导出Excel

        public static void ExportExcel(DataTable dt, string fileName = "")        {            //生成Excel            IWorkbook book = BuildWorkbook(dt);            //web 下载            if (fileName == "")                fileName = string.Format("{0:yyyyMMddHHmmssffff}", DateTime.Now);            fileName = fileName.Trim();            string ext = Path.GetExtension(fileName);            if (ext.ToLower() == ".xls" || ext.ToLower() == ".xlsx")                fileName = fileName.Replace(ext, string.Empty);            HttpResponse httpResponse = HttpContext.Current.Response;            httpResponse.Clear();            httpResponse.Buffer = true;            httpResponse.Charset = Encoding.UTF8.BodyName;            httpResponse.AppendHeader("Content-Disposition", "attachment;filename=" + fileName + ".xls");            httpResponse.ContentEncoding = Encoding.UTF8;            httpResponse.ContentType = "application/vnd.ms-excel; charset=UTF-8";            book.Write(httpResponse.OutputStream);            httpResponse.End();        }