C#使用NPOI对Excel数据进行导入导出

DataTable dt = ImportToTable("00.xls");
if (dt != null)
{
    Console.Write(dt.Rows.Count);
    Console.ReadKey();
}

public static DataTable ImportToTable(string fileName)
{
    DataTable dt = new DataTable();
    IWorkbook workbook;
    string fileExt = Path.GetExtension(fileName).ToLower();
    using (FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read))
    {
        //XSSFWorkbook 适用XLSX格式，HSSFWorkbook 适用XLS格式
        if (fileExt == ".xlsx")
        {
            workbook = new XSSFWorkbook(fs);
        }
        else if (fileExt == ".xls")
        {
            workbook = new HSSFWorkbook(fs);
        }
        else
        {
            workbook = null;
            return null;
        }

        ISheet sheet = workbook.GetSheetAt(0);//Sheet总数量：workbook.NumberOfSheets

        //表头  
        IRow header = sheet.GetRow(sheet.FirstRowNum);
        for (int i = 0; i < header.LastCellNum; i++)
        {
            object obj = GetValueType(header.GetCell(i));
            if (obj == null || obj.ToString() == string.Empty)
            {
                dt.Columns.Add(new DataColumn("Columns" + i.ToString()));
            }
            else

                dt.Columns.Add(new DataColumn(obj.ToString()));
        }
        //数据  
        for (int i = sheet.FirstRowNum + 1; i <= sheet.LastRowNum; i++)
        {
            DataRow dr = dt.NewRow();
            bool hasValue = false;
            IRow row = sheet.GetRow(i);
            for (int j = row.FirstCellNum; j < row.LastCellNum; j++)
            {
                dr[j] = GetValueType(sheet.GetRow(i).GetCell(j));
                if (dr[j] != null && dr[j].ToString() != string.Empty)
                {
                    hasValue = true;
                }
            }
            if (hasValue)
            {
                dt.Rows.Add(dr);
            }
        }

        return dt;
    }

}
/// 

/// 获取单元格类型
/// 
/// 
/// 
/// 
static object GetValueType(ICell cell)
{
    if (cell == null)
        return null;
    switch (cell.CellType)
    {
        case CellType.Blank: //BLANK:  
            return null;
        case CellType.Boolean: //BOOLEAN:  
            return cell.BooleanCellValue;
        case CellType.Numeric: //NUMERIC:  
            return cell.NumericCellValue;
        case CellType.String: //STRING:  
            return cell.StrinGCellValue;
        case CellType.Error: //ERROR:  
            return cell.ErrorCellValue;
        case CellType.Formula: //FORMULA:  
        default:
            return "=" + cell.CellFormula;
    }
}

IEnumerator rows = sheet.GetEnumerator();
while (rows.MoveNext())
{
    IRow row = (HSSFRow)rows.Current;
    ICell cell = row.GetCell(0);
    if (cell != null && cell.StringCellValue == "XX")
    {
        return row.GetCell(1).StringCellValue;
    }
}

IWorkbook workbook = new HSSFWorkbook();

//add picture data to this workbook.
byte[] bytes = System.IO.File.ReadAllBytes(@"00.jpg");
int pictureIdx = workbook.AddPicture(bytes, PictureType.JPEG);

//create sheet
ISheet sheet = workbook.CreateSheet("Sheet1");

// Create the drawing patriarch.  This is the top level container for all shapes. 
IDrawing patriarch = sheet.CreateDrawingPatriarch();

//add a picture
HSSFClientAnchor anchor = new HSSFClientAnchor(0, 0, 1023, 0, 0, 0, 1, 3);
IPicture pict = patriarch.CreatePicture(anchor, pictureIdx);

//保存为Excel文件  
using (FileStream fs = new FileStream("00_new.xls", FileMode.Create, FileAccess.Write))
{
    workbook.Write(fs);
}

IWorkbook workbook;
using (FileStream fs = new FileStream("模板文件.xls", FileMode.Open, FileAccess.Read))
{
    workbook = new HSSFWorkbook(fs);
}

ISheet cloneSheet = workbook.CloneSheet(workbook.GetSheetIndex("Sheet1"));//复制第一个模板Sheet
cloneSheet.ForceFormulaRecalculation = true;
workbook.SetSheetName(workbook.GetSheetIndex(cloneSheet), "SheetClone");//设置新SheetName

cloneSheet.GetRow(4).GetCell(1).SetCellValue("a");//为已经存在的单元格赋值

IRow row = cloneSheet.GetRow(15);
if (row == null)
    row = cloneSheet.CreateRow(15);
ICell cell = row.GetCell(7);
if (cell == null)
    cell = row.CreateCell(7);
cell.SetCellValue("XX");// 为不存在的单元格，先新建再赋值

cloneSheet.ShiftRows(51, 60, 34);//51-60行（尾部）整体移动34行，腾出更多控件插入多行数据
workbook.RemoveSheetAt(workbook.GetSheetIndex("Sheet1"));//移除原模板Sheet

FileStream fs_new = new FileStream(DateTime.Now.Ticks + ".xls", FileMode.Create);
workbook.Write(fs_new);
fs_new.Close();

ExportToExcel(dt, "00_new.xls");

public static void ExportToExcel(DataTable dt, string fileName)
{
    IWorkbook workbook;
    string fileExt = Path.GetExtension(fileName).ToLower();
    //XSSFWorkbook 适用XLSX格式，HSSFWorkbook 适用XLS格式
    if (fileExt == ".xlsx")
    {
        workbook = new XSSFWorkbook();
    }
    else if (fileExt == ".xls")
    {
        workbook = new HSSFWorkbook();
    }
    else
    {
        workbook = null;
        return;
    }

    ISheet sheet = string.IsNullOrEmpty(dt.TableName) ? workbook.CreateSheet("Sheet1") : workbook.CreateSheet(dt.TableName);

    //表头  
    IRow row = sheet.CreateRow(0);
    for (int i = 0; i < dt.Columns.Count; i++)
    {
        ICell cell = row.CreateCell(i);
        cell.SetCellValue(dt.Columns[i].ColumnName);
    }

    //数据  
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        IRow row1 = sheet.CreateRow(i + 1);
        for (int j = 0; j < dt.Columns.Count; j++)
        {
            ICell cell = row1.CreateCell(j);
            cell.SetCellValue(dt.Rows[i][j].ToString());
        }
    }

    //保存为Excel文件  
    using (FileStream fs = new FileStream(fileName, FileMode.Create, FileAccess.Write))
    {
        workbook.Write(fs);
    }
}

public static MemoryStream ExportToExcel(DataTable dt, string HeaderText)
{
    var workbook = new HSSFWorkbook();
    ISheet sheet = workbook.CreateSheet(string.IsNullOrWhiteSpace(dt.TableName) ? "Sheet1" : dt.TableName);

    //右击文件“属性”信息
    #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

    //格式
    var dateStyle = workbook.CreateCellStyle();
    var format = workbook.CreateDataFormat();
    dateStyle.DataFormat = format.GetFormat("yyyy-mm-dd");//日期格式

    //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();//超过65535行，则新建一个Sheet
            }

            #region 表头及样式
            {
                var headerRow = sheet.CreateRow(0);
                headerRow.HeightInPoints = 25;
                headerRow.CreateCell(0).SetCellValue(HeaderText);
                //CellStyle
                ICellStyle headStyle = workbook.CreateCellStyle();
                headStyle.Alignment = NPOI.SS.UserModel.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 NPOI.SS.Util.CellRangeAddress(0, 0, 0, dt.Columns.Count - 1));//合并区域
            }
            #endregion


            #region 列头及样式
            {
                var headerRow = sheet.CreateRow(1);
                //CellStyle
                ICellStyle headStyle = workbook.CreateCellStyle();
                headStyle.Alignment = NPOI.SS.UserModel.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);//设置列宽
                }
            }
            #endregion

            rowIndex = 2;//数据行RowIndex为2（表头和列头个占一行）
        }
        #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("");//设置单元格公式：newCell.SetCellFormula("SUM($B0:$D0)")
                    break;
            }

        }
        #endregion

        rowIndex++;
    }
    //自动列宽
    for (int i = 0; i <= dt.Columns.Count; i++)
        sheet.AutoSizeColumn(i, true);

    using (MemoryStream ms = new MemoryStream())
    {
        workbook.Write(ms);
        ms.Flush();
        ms.Position = 0;
        return ms;
    }
}

public static void ExportToExcelByWeb(DataTable dt, string HeaderText, string FileName)
{
    HttpContext context = HttpContext.Current;
    context.Response.ContentType = "application/vnd.ms-excel";
    context.Response.ContentEncoding = Encoding.UTF8;
    context.Response.Charset = "UTF-8";
    context.Response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}.xls", HttpUtility.UrlEncode(FileName, Encoding.UTF8)));
    byte[] data = ExportToExcel(dt, HeaderText).GetBuffer();//Read（）方法也可以
    context.Response.BinaryWrite(data);//     或者： context.Response.OutputStream.Write(data,0,data.Length)
    context.Response.End();
}

public static void ExportToExcel(DataTable dt, string HeaderText, string FileName)
{
    using (MemoryStream ms = ExportToExcel(dt, HeaderText))
    {
        using (FileStream fs = new FileStream(FileName, FileMode.Create, FileAccess.Write))
        {
            byte[] data = ms.ToArray();//跟GetBuffer（）对比，速度稍慢，但无空数据
            fs.Write(data, 0, data.Length);
            fs.Flush();
        }
    }
}