利用NPOI解析Excel的通用类

using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System;

public class ExcelHelp
{
    public class x2003
    {
        #region Excel2003
        /// <summary>
        /// 将Excel文件中的数据读出到DataTable中(xls)
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        public static DataTable ExcelToTableForXLS(string file)
        {
            DataTable dt = new DataTable();
            using (FileStream fs = new FileStream(file, FileMode.Open, FileAccess.Read))
            {
                HSSFWorkbook hssfworkbook = new HSSFWorkbook(fs);
                ISheet sheet = hssfworkbook.GetSheetAt(0);

                //表头
                IRow header = sheet.GetRow(sheet.FirstRowNum);
                List<int> columns = new List<int>();
                for (int i = 0; i < header.LastCellNum; i++)
                {
                    object obj = GetValueTypeForXLS(header.GetCell(i) as HSSFCell);
                    if (obj == null || obj.ToString() == string.Empty)
                    {
                        dt.Columns.Add(new DataColumn("Columns" + i.ToString()));
                        //continue;
                    }
                    else
                        dt.Columns.Add(new DataColumn(obj.ToString()));
                    columns.Add(i);
                }
                //数据
                for (int i = sheet.FirstRowNum + 1; i <= sheet.LastRowNum; i++)
                {
                    DataRow dr = dt.NewRow();
                    bool hasValue = false;
                    foreach (int j in columns)
                    {
                        dr[j] = GetValueTypeForXLS(sheet.GetRow(i).GetCell(j) as HSSFCell);
                        if (dr[j] != null && dr[j].ToString() != string.Empty)
                        {
                            hasValue = true;
                        }
                    }
                    if (hasValue)
                    {
                        dt.Rows.Add(dr);
                    }
                }
            }
            return dt;
        }

        /// <summary>
        /// 将DataTable数据导出到Excel文件中(xls)
        /// </summary>
        /// <param name="dt"></param>
        /// <param name="file"></param>
        public static void TableToExcelForXLS(DataTable dt, string file)
        {
            HSSFWorkbook hssfworkbook = new HSSFWorkbook();
            ISheet sheet = hssfworkbook.CreateSheet("Test");

            //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());
                }
            }

            //转为字节数组
            MemoryStream stream = new MemoryStream();
            hssfworkbook.Write(stream);
            var buf = stream.ToArray();

            //保存为Excel文件
            using (FileStream fs = new FileStream(file, FileMode.Create, FileAccess.Write))
            {
                fs.Write(buf, 0, buf.Length);
                fs.Flush();
            }
        }

        /// <summary>
        /// 获取单元格类型(xls)
        /// </summary>
        /// <param name="cell"></param>
        /// <returns></returns>
        private static object GetValueTypeForXLS(HSSFCell 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;
            }
        }
        #endregion
    }

    public class x2007
    {
        #region Excel2007
        /// <summary>
        /// 将Excel文件中的数据读出到DataTable中(xlsx)
        /// </summary>
        /// <param name="file"></param>
        /// <returns></returns>
        public static DataTable ExcelToTableForXLSX(string file)
        {
            DataTable dt = new DataTable();
            using (FileStream fs = new FileStream(file, FileMode.Open, FileAccess.Read))
            {
                XSSFWorkbook xssfworkbook = new XSSFWorkbook(fs);
                ISheet sheet = xssfworkbook.GetSheetAt(0);

                //表头
                IRow header = sheet.GetRow(sheet.FirstRowNum);
                List<int> columns = new List<int>();
                for (int i = 0; i < header.LastCellNum; i++)
                {
                    object obj = GetValueTypeForXLSX(header.GetCell(i) as XSSFCell);
                    if (obj == null || obj.ToString() == string.Empty)
                    {
                        dt.Columns.Add(new DataColumn("Columns" + i.ToString()));
                        //continue;
                    }
                    else
                        dt.Columns.Add(new DataColumn(obj.ToString()));
                    columns.Add(i);
                }
                //数据
                for (int i = sheet.FirstRowNum + 1; i <= sheet.LastRowNum; i++)
                {
                    DataRow dr = dt.NewRow();
                    bool hasValue = false;
                    foreach (int j in columns)
                    {
                        dr[j] = GetValueTypeForXLSX(sheet.GetRow(i).GetCell(j) as XSSFCell);
                        if (dr[j] != null && dr[j].ToString() != string.Empty)
                        {
                            hasValue = true;
                        }
                    }
                    if (hasValue)
                    {
                        dt.Rows.Add(dr);
                    }
                }
            }
            return dt;
        }

        /// <summary>
        /// 将DataTable数据导出到Excel文件中(xlsx)
        /// </summary>
        /// <param name="dt"></param>
        /// <param name="file"></param>
        public static void TableToExcelForXLSX(DataTable dt, string file)
        {
            XSSFWorkbook xssfworkbook = new XSSFWorkbook();
            ISheet sheet = xssfworkbook.CreateSheet("sheet1");

            //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());
                }
            }

            //转为字节数组
            MemoryStream stream = new MemoryStream();
            xssfworkbook.Write(stream);
            var buf = stream.ToArray();

            //保存为Excel文件
            using (FileStream fs = new FileStream(file, FileMode.Create, FileAccess.Write))
            {
                fs.Write(buf, 0, buf.Length);
                fs.Flush();
            }
        }

        /// <summary>
        /// 获取单元格类型(xlsx)
        /// </summary>
        /// <param name="cell"></param>
        /// <returns></returns>
        private static object GetValueTypeForXLSX(XSSFCell 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;
            }
        }
        #endregion
    }

    public static DataTable GetDataTable(string filepath)
    {
        try
        {
            var dt = new DataTable("xls");
            if (filepath.Last() == 's')
            {
                dt = x2003.ExcelToTableForXLS(filepath);
            }
            else
            {
                dt = x2007.ExcelToTableForXLSX(filepath);
            }
            return dt;
        }
        catch (Exception ex)
        {
            return null;
        }
    }


    /// <summary>
    /// 将Excel文件中的数据读出到DataTable中
    /// </summary>
    /// <param name="file">文件路径</param>
    /// <param name="sheetName">工作表名称</param>
    /// <param name="columnTypeDic">列名与列类型字典</param>
    /// <returns>DataTable</returns>
    public static DataTable ImportToTable(string file, string sheetName = "", Dictionary<string, Type> columnTypeDic = null)
    {
        DataTable dt = null;
        FileStream fs = null;
        try
        {
            fs = new FileStream(file, FileMode.Open, FileAccess.Read);
            IWorkbook workbook = WorkbookFactory.Create(fs);
            ISheet sheet = string.IsNullOrEmpty(sheetName) ? workbook.GetSheetAt(0) : workbook.GetSheet(sheetName);
            if (sheet == null) return null;
            dt = SheetToDataTable(sheet, columnTypeDic);
            fs.Close();
            return dt;
        }
        catch (Exception ex)
        {
            if (fs != null)
            {
                fs.Close();
            }
            return dt;
        }
    }
    /// <summary>
    /// 将Excel文件中的数据读出到DataSet中
    /// </summary>
    /// <param name="file">Excel文件路径</param>
    /// <param name="columnTypeDic">列名与列类型字典</param>
    /// <returns>DataSet</returns>
    public static DataSet ImportToDataSet(string file, Dictionary<string, Type> columnTypeDic = null)
    {
        DataSet ds = new DataSet();
        FileStream fs = null;
        try
        {
            fs = new FileStream(file, FileMode.Open, FileAccess.Read);
            IWorkbook workbook = WorkbookFactory.Create(fs);
            int sheetCount = workbook.NumberOfSheets;
            for (int i = 0; i < sheetCount; i++)
            {
                ISheet sheet = workbook.GetSheetAt(i);
                if (sheet == null) continue;
                DataTable dt = SheetToDataTable(sheet, columnTypeDic);
                ds.Tables.Add(dt);
            }
            fs.Close();
            return ds;
        }
        catch (Exception ex)
        {
            if (fs != null)
            {
                fs.Close();
            }
            return ds;
        }
    }
    /// <summary>
    /// 将Sheet中的数据读出到DataTable中
    /// </summary>
    /// <param name="sheet">ISheet</param>
    /// <param name="columnTypeDic">列名与列类型字典</param>
    /// <returns>DataTable</returns>
    private static DataTable SheetToDataTable(ISheet sheet, Dictionary<string, Type> columnTypeDic)
    {
        DataTable dt = new DataTable(sheet.SheetName);
        //表头
        IRow header = sheet.GetRow(sheet.FirstRowNum);
        if (header == null) return dt;
        for (int i = 0; i < header.LastCellNum; i++)
        {
            ICell cell = header.GetCell(i);
            object obj = GetCellValue(cell);
            string columnName = "";
            if (obj == null || string.IsNullOrEmpty(obj.ToString()) || dt.Columns.Contains(obj.ToString()))
                columnName = "Columns" + i;
            else
                columnName = obj.ToString();
            if (obj != null && dt.Columns.Contains(obj.ToString()))
            {
            }
            if (columnTypeDic != null && columnTypeDic.ContainsKey(columnName))
                dt.Columns.Add(columnName, columnTypeDic[columnName]);
            else
                dt.Columns.Add(columnName);
        }

        //数据
        int firstRowNum = sheet.FirstRowNum;//耗时操作，只读一次，提升效率
        int lastRowNum = sheet.LastRowNum;
        for (int i = firstRowNum + 1; i <= lastRowNum; i++)
        {
            DataRow dr = dt.NewRow();
            bool hasValue = false;
            for (int j = 0; j < header.LastCellNum; j++)
            {
                IRow row = sheet.GetRow(i);
                if (row == null) continue;
                ICell cell = row.GetCell(j);
                if (cell == null) continue;
                dr[j] = GetCellValue(cell);
                if (dr[j] != null && dr[j].ToString() != string.Empty)
                {
                    hasValue = true;
                }
            }
            if (hasValue)
            {
                dt.Rows.Add(dr);
            }
        }
        return dt;
    }
    /// <summary>
    /// 获取单元格的值
    /// </summary>
    /// <param name="cell">ICell</param>
    /// <returns>object</returns>
    private static object GetCellValue(ICell cell)
    {
        if (cell == null)
            return null;
        try
        {
            CellType cellType = cell.CellType == CellType.Formula ? cell.CachedFormulaResultType : cell.CellType;
            switch (cellType)
            {
                case CellType.Blank: //BLANK:
                    return null;
                case CellType.Boolean: //BOOLEAN:
                    return cell.BooleanCellValue;
                case CellType.Numeric: //NUMERIC:
                    if (HSSFDateUtil.IsCellDateFormatted(cell))//日期类型
                    {
                        return cell.DateCellValue;
                    }
                    else//其他数字类型
                    {
                        return cell.NumericCellValue;
                    }
                case CellType.String: //STRING:
                    return cell.StringCellValue;
                case CellType.Error: //ERROR:
                    return cell.ErrorCellValue;
                default:
                    return null;
            }
        }
        catch (Exception ex)
        {
            return null;
        }
    }
}