一、Excel导入及导出问题产生：
从接触.net到现在一直在维护一个DataTable导出到Excel的类，时不时还会维护一个导入类。以下是时不时就会出现的问题：
导出问题：
如果是asp.net，你得在服务器端装Office，几百M呢，还得及时更新它，以防漏洞，还得设定权限允许ASP.net访问COM+，听说如果导出过程中出问题可能导致服务器宕机。
Excel会把只包含数字的列进行类型转换，本来是文本型的，它非要把你转成数值型的，像身份证后三位变成000，编号000123会变成123，够智能吧，够郁闷吧。不过这些都还是可以变通解决的，在他们前边加上一个字母，让他们不只包含数字。
导出时，如果你的字段内容以"-"或"="开头，Excel好像把它当成了公式什么的，接下来就出错，提示：类似，保存到Sheet1的问题
导入问题：
Excel会根据你的 Excel文件前8行分析数据类型，如果正好你前8行某一列只是数字，那它会认为你这一列就是数值型的，然后，身份证，手机，编号都转吧变成类似这样的1.42702E+17格式，日期列变成 包含日期和数字的，乱的很，可以通过改注册表让Excel分析整个表，但如果整列都是数字，那这个问题还是解决不了。
以上问题，一般人初次做时肯定得上网查查吧，一个问题接着另一个问题，查到你郁郁而死，还有很多问题没解决，最终感觉已经解决的不错了，但还不能保证某一天还会出个什么问题。
二、使用第三方开源组件导入及导出Excel的解决方案：
偶然间发现了NPOI与MyXls，相见恨晚，害的我在Excel上浪费了那么多时间，他们俩的好处是：就是.net的自定义类库，可以直接对Excel进行读或写，而不依赖Office 的 Excel，这不管对于ASP.net或Winform都非常有利，不用担心Excel进程的释放问题，服务器安全，设置，导出，导入“Excel智能识别”，公式日期等问题，可以说以前的Excel问题，全都不用管了，它们可以很好的帮你解决，NPOI || MyXls == 研究几年Excel。
NPOI开源地址：http://npoi.codeplex.com/
MyXls开源地址：http://sourceforge.net/projects/myxls/
三、下面来两个简单入门例子：
MyXls 快速入门例子:
/// <summary> /// MyXls简单Demo，快速入门代码 /// </summary> /// <param name="dtSource"></param> /// <param name="strFileName"></param> /// <remarks>MyXls认为Excel的第一个单元格是：(1,1)</remarks> public static void ExportEasy(DataTable dtSource, ?string strFileName) { ????XlsDocument xls = new XlsDocument(); ????Worksheet sheet = xls.Workbook.Worksheets.Add("Sheet1"); ?????//填充表头 ????foreach (DataColumn col in dtSource.Columns) ????{ ????????sheet.Cells.Add(1, col.Ordinal + 1, col.ColumnName); ????} ?????//填充内容 ????for (int i = 0; i < dtSource.Rows.Count; i++) ????{ ????????for (int j = 0; j < dtSource.Columns.Count; j++) ????????{ ????????????sheet.Cells.Add(i + 2, j + 1, dtSource.Rows[i][j].ToString()); ????????} ????} ?????//保存 ????xls.FileName = strFileName; ????xls.Save(); }NPOI 快速入门例子:
/// <summary> /// NPOI简单Demo，快速入门代码 /// </summary> /// <param name="dtSource"></param> /// <param name="strFileName"></param> /// <remarks>NPOI认为Excel的第一个单元格是：(0，0)</remarks> public static void ExportEasy(DataTable dtSource, string strFileName) { ????HSSFWorkbook workbook = new HSSFWorkbook(); ????HSSFSheet sheet = workbook.CreateSheet(); ?????//填充表头 ????HSSFRow dataRow = sheet.CreateRow(0); ????foreach (DataColumn column in dtSource.Columns) ????{ ????????dataRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName); ????} ??????//填充内容 ????for (int i = 0; i < dtSource.Rows.Count; i++) ????{ ????????dataRow = sheet.CreateRow(i + 1); ????????for (int j = 0; j < dtSource.Columns.Count; j++) ????????{ ????????????dataRow.CreateCell(j).SetCellValue(dtSource.Rows[i][j].ToString()); ????????} ????} ??????//保存 ????using (MemoryStream ms = new MemoryStream()) ????{ ????????using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write)) ????????{ ????????????workbook.Write(fs); ????????} ????} ????workbook.Dispose(); }四、接下来是封装的可以用在实际项目中的类，实现的功能有（仅NPOI）：
- 支持web及winform从DataTable导出到Excel。
- 生成速度很快。
- 准确判断数据类型，不会出现身份证转数值等上面提到的一系列问题。
- 如果单页条数大于65535时会新建工作表。
- 列宽自适应。
- 支持读取Excel。
- 调用方便，只一调用一个静态类就OK了。
- 因为测试期间发现MyXls导出速度要比NPOI慢3倍，而NPOI既能满足我们的导出需求，又能很好的满足我们的导入需求，所以只针对NPOI进行全方位功能实现及优化。
NPOI操作类 ?using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.IO; using System.Text; using NPOI; using NPOI.HPSF; using NPOI.HSSF; using NPOI.HSSF.UserModel; using NPOI.HSSF.Util; using NPOI.POIFS; using NPOI.Util; ??namespace SNF.Utilities { ????public class NPOIHelper ????{ ????????/// <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 Export(DataTable dtSource, string strHeaderText, string strFileName) ????????{ ????????????using (MemoryStream ms = Export(dtSource, strHeaderText)) ????????????{ ????????????????using (FileStream fs = new FileStream(strFileName, FileMode.Create, FileAccess.Write)) ????????????????{ ????????????????????byte[] data = ms.ToArray(); ????????????????????fs.Write(data, 0, data.Length); ????????????????????fs.Flush(); ????????????????} ????????????} ????????} ?????????/// <summary> ????????/// DataTable导出到Excel的MemoryStream ????????/// </summary> ????????/// <param name="dtSource">源DataTable</param> ????????/// <param name="strHeaderText">表头文本</param> ????????public static MemoryStream Export(DataTable dtSource, string strHeaderText) ????????{ ????????????HSSFWorkbook workbook = new HSSFWorkbook(); ????????????HSSFSheet sheet = workbook.CreateSheet(); ?????????????#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 = DateTime.Now; ????????????????workbook.SummaryInformation = si; ????????????} ????????????#endregion ?????????????HSSFCellStyle dateStyle = workbook.CreateCellStyle(); ????????????HSSFDataFormat format = 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 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 ????????????????????{ ????????????????????????HSSFRow headerRow = sheet.CreateRow(0); ????????????????????????headerRow.HeightInPoints = 25; ????????????????????????headerRow.CreateCell(0).SetCellValue(strHeaderText); ?????????????????????????HSSFCellStyle headStyle = workbook.CreateCellStyle(); ????????????????????????headStyle.Alignment = CellHorizontalAlignment.CENTER; ????????????????????????HSSFFont font = 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 ????????????????????{ ????????????????????????HSSFRow headerRow = sheet.CreateRow(1); ?????????????????????????HSSFCellStyle headStyle = workbook.CreateCellStyle(); ????????????????????????headStyle.Alignment = CellHorizontalAlignment.CENTER; ????????????????????????HSSFFont 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 ????????????????HSSFRow dataRow = sheet.CreateRow(rowIndex); ????????????????foreach (DataColumn column in dtSource.Columns) ????????????????{ ????????????????????HSSFCell 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++; ????????????} ?????????????using (MemoryStream ms = new MemoryStream()) ????????????{ ????????????????workbook.Write(ms); ????????????????ms.Flush(); ????????????????ms.Position = 0; ?????????????????sheet.Dispose(); ????????????????//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 curContext = HttpContext.Current; ?????????????// 设置编码和附件格式 ????????????curContext.Response.ContentType = "application/vnd.ms-excel"; ????????????curContext.Response.ContentEncoding = Encoding.UTF8; ????????????curContext.Response.Charset = ""; ????????????curContext.Response.AppendHeader("Content-Disposition", ????????????????"attachment;filename=" + HttpUtility.UrlEncode(strFileName, Encoding.UTF8)); ?????????????curContext.Response.BinaryWrite(Export(dtSource, strHeaderText).GetBuffer()); ????????????curContext.Response.End(); ?????????} ??????????/// <summary>读取excel ????????/// 默认第一行为标头 ????????/// </summary> ????????/// <param name="strFileName">excel文档路径</param> ????????/// <returns></returns> ????????public static DataTable Import(string strFileName) ????????{ ????????????DataTable dt = new DataTable(); ?????????????HSSFWorkbook hssfworkbook; ????????????using (FileStream file = new FileStream(strFileName, FileMode.Open, FileAccess.Read)) ????????????{ ????????????????hssfworkbook = new HSSFWorkbook(file); ????????????} ????????????HSSFSheet sheet = hssfworkbook.GetSheetAt(0); ????????????System.Collections.IEnumerator rows = sheet.GetRowEnumerator(); ?????????????HSSFRow headerRow = sheet.GetRow(0); ????????????int cellCount = headerRow.LastCellNum; ?????????????for (int j = 0; j < cellCount; j++) ????????????{ ????????????????HSSFCell cell = headerRow.GetCell(j); ????????????????dt.Columns.Add(cell.ToString()); ????????????} ?????????????for (int i = (sheet.FirstRowNum + 1); i <= sheet.LastRowNum; i++) ????????????{ ????????????????HSSFRow 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; ????????} ????} }五、NPOI操作类的调用方法
DataTable dt_Grade = Tools.Data.GetDataTable(strSQL);
filename += "绩效考核结果分数统计表";
PMS.Common.NPOIHelper.ExportByWeb(dt_Grade, filename, filename+".xls");
六、效果展示
七、NPOI类库下载：
NPOI 下载地址： http://npoi.codeplex.com/releases
官方学习网站 ： http://tonyqus.sinaapp.com/
信息来源：http://www.cnblogs.com/yongfa365/archive/2010/05/10/NPOI-MyXls-DataTable-To-Excel-From-Excel.html
八、参考地址：
NPOI导出Excel表功能实现(多个工作簿)：http://www.cnblogs.com/zhengjuzhuan/archive/2010/02/01/1661103.html
在 Server 端存取 Excel 檔案的利器：NPOI Library：http://msdn.microsoft.com/zh-tw/ee818993.aspx
ASP.NET使用NPOI类库导出Excel：http://www.cnblogs.com/niunan/archive/2010/03/30/1700706.html
九、总结：
通过以上分析，我们不难发现，用NPOI或MyXls代替是Excel是很明智的，在发文前，我看到NPOI及MyXls仍然在活跃的更新中。在使用过程中发现这两个组件极相似，以前看过文章说他们使用的内核是一样的。还有NPOI是国人开发的，且有相关中文文档，在很多地方有相关引用，下载量也很大。并且它支持Excel，看到MyXls相关问题基本上没人回答，所以推荐使用NPOI。MyXls可以直接Cell.Font.Bold操作，而NPOI得使用CellType多少感觉有点麻烦。
出处：https://www.cnblogs.com/spring_wang/p/3145689.html
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简单使用NPOI读取和生成Excel文件
NPOI的下载地址：http://npoi.codeplex.com/
NPOI的使用教程（中文）：http://tonyqus.sinaapp.com/
这里只是写一些简单的例子以便查阅。
读取Excel文件：
NPOI的使用教程（中文）：http://tonyqus.sinaapp.com/
这里只是写一些简单的例子以便查阅。
读取Excel文件：
//打开Excel文件using (FileStream excelfs = new FileStream("c:\\workbook.xls", FileMode.Open, FileAccess.Read)){ ???//根据“文件流”来创建HSSFWorkbook，即整个excel的工作簿 ???HSSFWorkbook workbook = new HSSFWorkbook(excelfs); ???//获取excel的第一个sheet工作表 ???HSSFSheet sheet = (HSSFSheet)workbook.GetSheetAt(0); ???//循环读取所有行的内容 ???for (int i = sheet.FirstRowNum; i <= sheet.LastRowNum; i++) ???{ ???????DataRow newRow = table.NewRow(); ???????//读取excel的行 ????????HSSFRow row = (HSSFRow)sheet.GetRow(i); ???????if (row != null) ???????{ ???????????if (row.GetCell(0) != null) ???????????{ ???????????????//复制整行数据 ?????????????????for (int j = row.FirstCellNum; j < row.Cells.Count; j++) ???????????????{ ???????????????????newRow[j] = row.GetCell(j); ???????????????} ???????????????//添加到数据表中 ?????????????????table.Rows.Add(newRow); ???????????} ???????} ???}}生成Excel文件：
//新建workbook工作簿HSSFWorkbook workbook = new HSSFWorkbook();
//新建sheet工作表HSSFSheet sheet = (HSSFSheet)workbook.CreateSheet();
//设置默认列宽sheet.DefaultColumnWidth = 15;
//填充工作表的内容for (int i = 0; i < dataSource.Count; i++){ ???//新建row数据行 ???HSSFRow dataRow = (HSSFRow)sheet.CreateRow(i); ???//填充数据行的内容 ???for (int j = 0; j < dataSource.ToArray().Count(); j++) ???{ ???????//新建cell单元格并填充内容 ???????dataRow.CreateCell(j).SetCellValue(dataSource[i][j].ToString()); ???}}//保存文件using (FileStream fs = new FileStream("c:\\workbook.xls", FileMode.Create, FileAccess.Write)){ ???workbook.Write(fs);}出处：https://www.cnblogs.com/xwgli/archive/2013/04/07/3006151.html
NET使用NPOI组件导出Excel-入门示例及通用方法
原文地址：https://www.cnblogs.com/mq0036/p/9835949.html