NPOI库读写Excel文件

//首先Nuget安装NPOI库

using System;
using System.Data;
using System.IO;
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;


    public static class ExcelExtensions
    {
        /// <summary>
        /// DataSet数据导出到Excel文件
        /// </summary>
        /// <param name="ds">DataSet</param>
        /// <param name="fileName">文件全名</param>
        /// <returns></returns>
        public static bool DataSetToExcel(DataSet ds, string fileName)
        {
            IWorkbook workbook = new HSSFWorkbook();
            FileStream fs = null;
            try
            {
                int k = 0;
                foreach (DataTable dt in ds.Tables)
                {
                    if (dt != null && dt.Rows.Count > 0)
                    {
                        ISheet sheet = null;
                        if (!string.IsNullOrWhiteSpace(dt.TableName))
                        {
                            sheet = workbook.CreateSheet(dt.TableName);//创建一个名称为Sheet0的表
                        }
                        else
                        {
                            sheet = workbook.CreateSheet("Sheet" + k.ToString());//创建一个名称为Sheet0的表
                        }
                        int rowCount = dt.Rows.Count;//行数  
                        int columnCount = dt.Columns.Count;//列数

                        //设置列头  
                        IRow row = sheet.CreateRow(0);//excel第一行设为列头
                        ICell cell = null;
                        for (int c = 0; c < columnCount; c++)
                        {
                            cell = row.CreateCell(c);
                            cell.SetCellValue(dt.Columns[c].ColumnName);
                        }

                        //设置每行每列的单元格,  
                        for (int i = 0; i < rowCount; i++)
                        {
                            row = sheet.CreateRow(i + 1);
                            for (int j = 0; j < columnCount; j++)
                            {
                                cell = row.CreateCell(j);//excel第二行开始写入数据  
                                cell.SetCellValue(dt.Rows[i][j].ToString());
                            }
                        }
                        //设置最后一列单元格宽度
                        sheet.SetColumnWidth(columnCount - 1, 20000);
                        k = k + 1;
                    }
                }
                using (fs = File.OpenWrite(fileName))
                {
                    workbook.Write(fs);//向打开的这个xls文件中写入数据  
                }
                return true;
            }
            catch (Exception ex)
            {
                if (fs != null)
                {
                    fs.Close();
                }
                return false;
            }
        }

        /// <summary>
        /// 将excel导入到dataset
        /// </summary>
        /// <param name="filePath">excel路径</param>
        /// <param name="isColumnName">第一行是否是列名</param>
        /// <returns>返回datatable</returns>
        public static DataSet ExcelToDataSet(string filePath, bool isColumnName)
        {
            DataSet dataset = new DataSet();
            DataTable dataTable = null;
            FileStream fs = null;
            IWorkbook workbook = null;
            int startRow = 0;
            try
            {
                using (fs = File.OpenRead(filePath))
                {
                    // 2007版本
                    if (filePath.IndexOf(".xlsx") > 0)
                        workbook = new XSSFWorkbook(fs);
                    // 2003版本
                    else if (filePath.IndexOf(".xls") > 0)
                        workbook = new HSSFWorkbook(fs);

                    if (workbook != null)
                    {
                        for (int n = 0; n < workbook.NumberOfSheets; n++)
                        {
                            ISheet sheet = workbook.GetSheetAt(n); //读取第一个sheet，当然也可以循环读取每个sheet
                            dataTable = new DataTable();
                            if (sheet != null && sheet.SheetName != "")
                            {
                                dataTable.TableName = sheet.SheetName;
                                int rowCount = sheet.LastRowNum; //总行数
                                if (rowCount > 0)
                                {
                                    IRow firstRow = sheet.GetRow(0); //第一行
                                    int cellCount = firstRow.LastCellNum; //列数

                                    //构建datatable的列
                                    DataColumn column = null;
                                    ICell cell = null;
                                    if (isColumnName)
                                    {
                                        startRow = 1; //如果第一行是列名，则从第二行开始读取
                                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                                        {
                                            cell = firstRow.GetCell(i);
                                            if (cell != null)
                                            {
                                                if (cell.StringCellValue != null)
                                                {
                                                    column = new DataColumn(cell.StringCellValue);
                                                    dataTable.Columns.Add(column);
                                                }
                                            }
                                        }
                                    }
                                    else
                                    {
                                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                                        {
                                            column = new DataColumn("column" + (i + 1));
                                            dataTable.Columns.Add(column);
                                        }
                                    }

                                    //填充行
                                    for (int i = startRow; i <= rowCount; ++i)
                                    {
                                        IRow row = sheet.GetRow(i);
                                        if (row == null || string.IsNullOrWhiteSpace(row.Cells[0].ToString()))
                                            continue;

                                        DataRow dataRow = dataTable.NewRow();
                                        for (int j = row.FirstCellNum; j < cellCount; ++j)
                                        {
                                            cell = row.GetCell(j);
                                            if (cell == null)
                                            {
                                                dataRow[j] = "";
                                            }
                                            else
                                            {
                                                //CellType(Unknown = -1,Numeric = 0,String = 1,Formula = 2,Blank = 3,Boolean = 4,Error = 5,)
                                                switch (cell.CellType)
                                                {
                                                    case CellType.Blank:
                                                        dataRow[j] = "";
                                                        break;
                                                    case CellType.Numeric:
                                                        short format = cell.CellStyle.DataFormat;
                                                        //对时间格式（2015.12.5、2015/12/5、2015-12-5等）的处理
                                                        if (format == 14 || format == 31 || format == 57
                                                            || format == 58)
                                                            dataRow[j] = cell.DateCellValue;
                                                        else
                                                            dataRow[j] = cell.NumericCellValue;
                                                        break;
                                                    case CellType.String:
                                                        dataRow[j] = cell.StringCellValue;
                                                        break;
                                                }
                                            }
                                        }
                                        dataTable.Rows.Add(dataRow);
                                    }
                                }
                            }
                            dataset.Tables.Add(dataTable);
                        }
                    }
                }
                return dataset;
            }
            catch (Exception)
            {
                if (fs != null)
                {
                    fs.Close();
                }
                return null;
            }
        }
    }