c# NPOI 方式读取 EXCEL表 类

参考链接：https://www.cnblogs.com/chunxiong/p/9406178.html

稍微修改了一下。。。学习学习！！

namespace NPOIClass
{
    public class NPOIC
    {
        private static int sheetCellNumMax = 12;

        /// <summary>
        /// 获取sheet表名
        /// </summary>
        /// <param name="filePath"></param>
        /// <returns></returns>
        public static string[] GetSheetName(string filePath)
        {
            int sheetNumber = 0;
            var file = new FileStream(filePath, FileMode.Open, FileAccess.Read);
            if (filePath.IndexOf(".xlsx") > 0)
            {
                //2007版本
                var xssfworkbook = new XSSFWorkbook(file);
                sheetNumber = xssfworkbook.NumberOfSheets;

                string[] sheetNames = new string[sheetNumber];

                for (int i = 0; i < sheetNumber; i++)
                {
                    sheetNames[i] = xssfworkbook.GetSheetName(i);
                }
                return sheetNames;
            }
            else if (filePath.IndexOf(".xls") > 0)
            {
                //2003版本
                var hssfworkbook = new HSSFWorkbook(file);
                sheetNumber = hssfworkbook.NumberOfSheets;

                string[] sheetNames = new string[sheetNumber];

                for (int i = 0; i < sheetNumber; i++)
                {
                    sheetNames[i] = hssfworkbook.GetSheetName(i);
                }
                return sheetNames;
            }
            return null;
        }

        /// <summary>
        /// 根据表名获取表
        /// </summary>
        /// <param name="filePath"></param>
        /// <param name="sheetName"></param>
        /// <returns></returns>
        public static DataTable ExcelToDataTable(string filePath, string sheetName)
        {
            string outMsg = "";
            var dt = new DataTable();
            string fileType = Path.GetExtension(filePath).ToLower();

            try
            {
                ISheet sheet = null;
                FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
                if (fileType == ".xlsx")
                {
                    //2007版
                    XSSFWorkbook workbook = new XSSFWorkbook(fs);
                    sheet = workbook.GetSheet(sheetName);
                    if (sheet != null)
                    {
                        dt = GetSheetDataTable(sheet, out outMsg);
                    }
                }
                else if (fileType == ".xls")
                {
                    //2003版
                    HSSFWorkbook workbook = new HSSFWorkbook(fs);
                    sheet = workbook.GetSheet(sheetName);
                    if (sheet != null)
                    {
                        dt = GetSheetDataTable(sheet, out outMsg);
                    }
                }


            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }


            return dt;
        }

        /// <summary>
        /// 获取sheet表对应的DataTable
        /// </summary>
        /// <param name="sheet">Excel工作表</param>
        /// <param name="strMsg"></param>
        /// <returns></returns>
        private static DataTable GetSheetDataTable(ISheet sheet, out string strMsg)
        {
            strMsg = "";
            DataTable dt = new DataTable();
            string sheetName = sheet.SheetName;
            int startIndex = 0;// sheet.FirstRowNum;
            int lastIndex = sheet.LastRowNum;

            //最大列数
            int cellCount = 0;
            IRow maxRow = sheet.GetRow(0);
            for (int i = startIndex; i <= lastIndex; i++)
            {
                IRow row = sheet.GetRow(i);
                if (row != null && cellCount < row.LastCellNum)
                {
                    cellCount = row.LastCellNum;
                    maxRow = row;
                }
            }
            //列名设置
            try
            {
                //maxRow.LastCellNum = 12 // L
                for (int i = 0; i < sheetCellNumMax; i++)//maxRow.FirstCellNum
                {
                    dt.Columns.Add(Convert.ToChar(((int)'A') + i).ToString());
                    //DataColumn column = new DataColumn("Column" + (i + 1).ToString());
                    //dt.Columns.Add(column);
                }
            }
            catch
            {
                strMsg = "工作表" + sheetName + "中无数据";
                return null;
            }
            //数据填充
            for (int i = startIndex; i <= lastIndex; i++)
            {
                IRow row = sheet.GetRow(i);
                DataRow drNew = dt.NewRow();
                if (row != null)
                {
                    for (int j = row.FirstCellNum; j < row.LastCellNum; ++j)
                    {
                        if (row.GetCell(j) != null)
                        {
                            ICell cell = row.GetCell(j);
                            switch (cell.CellType)
                            {
                                case CellType.Blank:
                                    drNew[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)
                                        drNew[j] = cell.DateCellValue;
                                    else
                                        drNew[j] = cell.NumericCellValue;
                                    if (cell.CellStyle.DataFormat == 177 || cell.CellStyle.DataFormat == 178 || cell.CellStyle.DataFormat == 188)
                                        drNew[j] = cell.NumericCellValue.ToString("#0.00");
                                    break;
                                case CellType.String:
                                    drNew[j] = cell.StringCellValue;
                                    break;
                                case CellType.Formula:
                                    try
                                    {
                                        drNew[j] = cell.NumericCellValue;
                                        if (cell.CellStyle.DataFormat == 177 || cell.CellStyle.DataFormat == 178 || cell.CellStyle.DataFormat == 188)
                                            drNew[j] = cell.NumericCellValue.ToString("#0.00");
                                    }
                                    catch
                                    {
                                        try
                                        {
                                            drNew[j] = cell.StringCellValue;
                                        }
                                        catch { }
                                    }
                                    break;
                                default:
                                    drNew[j] = cell.StringCellValue;
                                    break;
                            }
                        }
                    }
                }
                dt.Rows.Add(drNew);
            }
            return dt;
        }
    }
}