Excel导入到DataTable ，DataTable导入到Excel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using NPOI.HSSF.UserModel;
using System.IO;
using System.Data;
using NPOI.SS.Util;
using NPOI.HSSF.Util;// 列

namespace Common.Utility
{
    public class ExcelHelper : IDisposable
    {
        private string fileName = null; //文件名
        private IWorkbook workbook = null;
        private FileStream fs = null;
        private bool disposed;

        public ExcelHelper(string fileName)
        {
            this.fileName = fileName;
            disposed = false;
        }

        /// <summary>
        /// 将DataTable数据导入到excel中
        /// </summary>
        /// <param name="data">要导入的数据</param>
        /// <param name="isColumnWritten">DataTable的列名是否要导入</param>
        /// <param name="sheetName">要导入的excel的sheet的名称</param>
        /// <returns>导入数据行数(包含列名那一行)</returns>
        public int DataTableToExcel(DataTable data, string sheetName, bool isColumnWritten,string args="")
        {
            int i = 0;
            int j = 0;
            int count = 0;
            ISheet sheet = null;

            fs = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite);
            if (fileName.IndexOf(".xlsx") > 0) // 2007版本
                workbook = new XSSFWorkbook();
            else if (fileName.IndexOf(".xls") > 0) // 2003版本
                workbook = new HSSFWorkbook();

            try
            {
                if (workbook != null)
                {
                    sheet = workbook.CreateSheet(sheetName);
                }
                else
                {
                    return -1;
                }

                if (isColumnWritten == true) //写入DataTable的列名
                {
                    IRow row = sheet.CreateRow(0);
                    for (j = 0; j < data.Columns.Count; ++j)
                    {
                        row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
                    }
                    count = 1;
                }
                else
                {
                    count = 0;
                }

                for (i = 0; i < data.Rows.Count; ++i)
                {
                    IRow row = sheet.CreateRow(count);
                    for (j = 0; j < data.Columns.Count; ++j)
                    {
                        row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                        if (args == "export_code" && data.Rows[i][j].ToString()=="合计")
                        {

                            SetCellRangeAddress(sheet, i + 1, i + 1, 0, 3);
                            IRow row_1 = sheet.GetRow(i + 1);
                            ICell cell = row_1.GetCell(0);
                            ICellStyle cellstyle = workbook.CreateCellStyle();//设置垂直居中格式
                            cellstyle.VerticalAlignment = VerticalAlignment.Justify;//垂直居中
                            cellstyle.Alignment = HorizontalAlignment.Center;
                            cell.CellStyle = cellstyle;

                        }
                    }
                    ++count;
                }
                if (args == "export_code")
                {
                    var oldCode = "";
                    int n = 0;
                    for (i = 0; i < data.Rows.Count; ++i)
                    {
                        var code = data.Rows[i][1];
                        if (oldCode == "")
                        {
                            oldCode = code.ToString();
                            n = i;
                        }
                        if (oldCode != code.ToString())
                        {

                            SetCellRangeAddress(sheet, n + 1, i, 1, 1);
                            IRow row = sheet.GetRow(n + 1);
                            ICell cell = row.GetCell(1);
                            ICellStyle cellstyle = workbook.CreateCellStyle();//设置垂直居中格式
                            cellstyle.VerticalAlignment = VerticalAlignment.Justify;//垂直居中
                            cellstyle.Alignment = HorizontalAlignment.Center;
                            cell.CellStyle = cellstyle;

                        }
                        if (data.Rows[i][4].ToString() == "合计")
                        {
                            oldCode = "";
                        }
                    }
                }

                workbook.Write(fs); //写入到excel
                return count;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
                return -1;
            }
        }

        #region
        /// <summary>
        /// 获取单元格样式
        /// </summary>
        /// <param name="hssfworkbook">Excel操作类</param>
        /// <param name="font">单元格字体</param>
        /// <param name="fillForegroundColor">图案的颜色</param>
        /// <param name="fillPattern">图案样式</param>
        /// <param name="fillBackgroundColor">单元格背景</param>
        /// <param name="ha">垂直对齐方式</param>
        /// <param name="va">垂直对齐方式</param>
        /// <returns></returns>
        public static ICellStyle GetCellStyle(HSSFWorkbook hssfworkbook,  HSSFColor fillBackgroundColor, HorizontalAlignment ha, VerticalAlignment va)
        {
            ICellStyle cellstyle = hssfworkbook.CreateCellStyle();
            cellstyle.Alignment = ha;
            cellstyle.VerticalAlignment = va;
            if (fillBackgroundColor != null)
            {
                cellstyle.FillBackgroundColor = fillBackgroundColor.GetIndex();
            }
            return cellstyle;
        }
        /// <summary>
        /// 合并单元格
        /// </summary>
        /// <param name="sheet">要合并单元格所在的sheet</param>
        /// <param name="rowstart">开始行的索引</param>
        /// <param name="rowend">结束行的索引</param>
        /// <param name="colstart">开始列的索引</param>
        /// <param name="colend">结束列的索引</param>
        public static void SetCellRangeAddress(ISheet sheet, int rowstart, int rowend, int colstart, int colend)
        {
            CellRangeAddress cellRangeAddress = new CellRangeAddress(rowstart, rowend, colstart, colend);
            sheet.AddMergedRegion(cellRangeAddress);
        }

        #endregion

        /// <summary>
        /// 将excel中的数据导入到DataTable中
        /// </summary>
        /// <param name="sheetName">excel工作薄sheet的名称</param>
        /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param>
        /// <returns>返回的DataTable</returns>
        public DataTable ExcelToDataTable(string sheetName, bool isFirstRowColumn)
        {
            ISheet sheet = null;
            DataTable data = new DataTable();
            int startRow = 0;
            try
            {
                fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                if (fileName.IndexOf(".xlsx") > 0) // 2007版本
                    workbook = new XSSFWorkbook(fs);
                else if (fileName.IndexOf(".xls") > 0) // 2003版本
                    workbook = new HSSFWorkbook(fs);

                if (sheetName != null)
                {
                    sheet = workbook.GetSheet(sheetName);
                    if (sheet == null) //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet
                    {
                        sheet = workbook.GetSheetAt(0);
                    }
                }
                else
                {
                    sheet = workbook.GetSheetAt(0);
                }
                if (sheet != null)
                {
                    IRow firstRow = sheet.GetRow(0);
                    int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数

                    if (isFirstRowColumn)
                    {
                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                        {
                            ICell cell = firstRow.GetCell(i);
                            if (cell != null)
                            {
                                string cellValue = cell.StringCellValue;
                                if (cellValue != null)
                                {
                                    DataColumn column = new DataColumn(cellValue);
                                    data.Columns.Add(column);
                                }
                            }
                        }
                        startRow = sheet.FirstRowNum + 1;
                    }
                    else
                    {
                        startRow = sheet.FirstRowNum;
                    }

                    //最后一列的标号
                    int rowCount = sheet.LastRowNum;
                    ICell tempcell = null;
                    for (int i = startRow; i <= rowCount; ++i)
                    {
                        IRow row = sheet.GetRow(i);
                        if (row == null) continue; //没有数据的行默认是null　　　　　　　

                        DataRow dataRow = data.NewRow();
                        for (int j = row.FirstCellNum; j < cellCount; ++j)
                        {
                            tempcell = row.GetCell(j);
                            if (tempcell != null) //同理，没有数据的单元格都默认是null
                            {
                                switch (tempcell.CellType)
                                {
                                    case CellType.Blank:
                                        dataRow[j] = "";
                                        break;
                                    case CellType.String:
                                        dataRow[j] = tempcell.StringCellValue;
                                        break;
                                    case CellType.Numeric:
                                            dataRow[j] = tempcell.NumericCellValue;
                                        break;
                                    case CellType.Formula:
                                        dataRow[j] = tempcell.NumericCellValue;
                                        break;
                                    default:
                                        dataRow[j] = "";
                                        break;
                                }
                            }
                        }
                        data.Rows.Add(dataRow);
                    }
                }

                return data;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
                throw ex;
                //return null;
            }
        }

        /// <summary>
        /// 将excel中的数据导入到DataTable中,增加多个sheet的情况
        /// </summary>
        /// <param name="sheetName">excel工作薄sheet的名称</param>
        /// <param name="isFirstRowColumn">第一行是否是DataTable的列名</param>
        /// <returns>返回的DataTable</returns>
        public DataTable ExcelToDataTable(int sheetIndex, bool isFirstRowColumn)
        {
            ISheet sheet = null;
            DataTable data = new DataTable();
            int startRow = 0;
            try
            {
                fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                if (fileName.IndexOf(".xlsx") > 0) // 2007版本
                    workbook = new XSSFWorkbook(fs);
                else if (fileName.IndexOf(".xls") > 0) // 2003版本
                    workbook = new HSSFWorkbook(fs);

                sheet = workbook.GetSheetAt(sheetIndex);
                if (sheet != null)
                {
                    IRow firstRow = sheet.GetRow(0);
                    int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数
                    if (isFirstRowColumn)
                    {
                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                        {
                            ICell cell = firstRow.GetCell(i);
                            if (cell != null)
                            {
                                string cellValue = cell.StringCellValue;
                                if (cellValue != null)
                                {
                                    DataColumn column = new DataColumn(cellValue);
                                    data.Columns.Add(column);
                                }
                            }
                        }
                        startRow = sheet.FirstRowNum + 1;
                    }
                    else
                    {
                        startRow = sheet.FirstRowNum;
                    }

                    //最后一列的标号
                    int rowCount = sheet.LastRowNum;
                    ICell tempcell = null;
                    for (int i = startRow; i <= rowCount; ++i)
                    {
                        IRow row = sheet.GetRow(i);
                        if (row == null) continue; //没有数据的行默认是null　　　　　　　

                        DataRow dataRow = data.NewRow();
                        for (int j = row.FirstCellNum; j < cellCount; ++j)
                        {
                            tempcell = row.GetCell(j);
                            if (tempcell != null) //同理，没有数据的单元格都默认是null
                            {
                                switch (tempcell.CellType)
                                {
                                    case CellType.Blank:
                                        dataRow[j] = "";
                                        break;
                                    case CellType.String:
                                        dataRow[j] = tempcell.StringCellValue;
                                        break;
                                    case CellType.Numeric:
                                        dataRow[j] = tempcell.NumericCellValue;
                                        break;
                                    case CellType.Formula:
                                        dataRow[j] = tempcell.NumericCellValue;
                                        break;
                                    default:
                                        dataRow[j] = "";
                                        break;
                                }
                            }
                        }
                        data.Rows.Add(dataRow);
                    }
                }

                return data;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
                throw ex;
            }
        }
        public DataTable ExcelToDataTable(int sheetIndex, int RowIndex, bool isFirstRowColumn)
        {
            ISheet sheet = null;
            DataTable data = new DataTable();
            int startRow = 0;
            try
            {
                fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                if (fileName.IndexOf(".xlsx") > 0) // 2007版本
                    workbook = new XSSFWorkbook(fs);
                else if (fileName.IndexOf(".xls") > 0) // 2003版本
                    workbook = new HSSFWorkbook(fs);

                sheet = workbook.GetSheetAt(sheetIndex);
                if (sheet != null)
                {
                    IRow firstRow = sheet.GetRow(RowIndex);
                    int cellCount = firstRow.LastCellNum; //一行最后一个cell的编号 即总的列数
                    if (isFirstRowColumn)
                    {
                        for (int i = firstRow.FirstCellNum; i < cellCount; ++i)
                        {
                            ICell cell = firstRow.GetCell(i);
                            if (cell != null)
                            {
                                string cellValue = cell.StringCellValue;
                                if (cellValue != null)
                                {
                                    DataColumn column = new DataColumn(cellValue);
                                    data.Columns.Add(column);
                                }
                            }
                        }
                        startRow = sheet.FirstRowNum + 1+ RowIndex;
                    }
                    else
                    {
                        startRow = sheet.FirstRowNum+ RowIndex;
                    }

                    //最后一列的标号
                    int rowCount = sheet.LastRowNum;
                    ICell tempcell = null;
                    for (int i = startRow; i <= rowCount; ++i)
                    {
                        IRow row = sheet.GetRow(i);
                        if (row == null) continue; //没有数据的行默认是null　　　　　　　

                        DataRow dataRow = data.NewRow();
                        for (int j = row.FirstCellNum; j < cellCount; ++j)
                        {
                            tempcell = row.GetCell(j);
                            if (tempcell != null) //同理，没有数据的单元格都默认是null
                            {
                                switch (tempcell.CellType)
                                {
                                    case CellType.Blank:
                                        dataRow[j] = "";
                                        break;
                                    case CellType.String:
                                        dataRow[j] = tempcell.StringCellValue;
                                        break;
                                    case CellType.Numeric:
                                        dataRow[j] = tempcell.NumericCellValue;
                                        break;
                                    case CellType.Formula:
                                        dataRow[j] = tempcell.NumericCellValue;
                                        break;
                                    default:
                                        dataRow[j] = "";
                                        break;
                                }
                            }
                        }
                        data.Rows.Add(dataRow);
                    }
                }

                return data;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
                throw ex;
            }
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (!this.disposed)
            {
                if (disposing)
                {
                    if (fs != null)
                        fs.Close();
                }

                fs = null;
                disposed = true;
            }
        }
    }
}