Npoi操作Excel

    1.读取Excel的多个sheet到DataSet里面 

  public DataSet GetDataSetFromExcel(string path)
        {
            DataSet set = new DataSet();
            FileStream fs;
            try
            {
                fs = new FileStream(path, FileMode.Open, FileAccess.Read);
            }
            catch (Exception)
            {

                // MessageBox.Show("文件被其他程序占用，请先关闭");
                return set;
            }

            bool isCompatible = GetIsCompatible(path);

            IWorkbook workbook = CreateWorkbook(isCompatible, fs);

            //获取Excel中有几个sheet
            int sheetNum = workbook.NumberOfSheets;

            string sheetName = "";

            ///Excel中的一个sheet
            ISheet sheet = null;
            int sheetIndex = -1;

            for (int i = 0; i < sheetNum; i++)
            {
                sheetName = workbook.GetSheetName(i);

                if (int.TryParse(sheetName, out sheetIndex))
                {
                    sheet = workbook.GetSheetAt(sheetIndex);
                }
                else
                {
                    sheet = workbook.GetSheet(sheetName);
                }
                // 示例的excel 第一行是个大标题，第二行才是标题行,所以下面这个标题行的索引为1
                set.Tables.Add(GetDataTableFromSheet(sheet, 1));
            }

            fs.Close();
            workbook = null;
            sheet = null;

            return set;
           
        }


        /// <summary>
        /// 从工作表中生成DataTable
        /// </summary>
        /// <param name="sheet">sheet 名</param>
        /// <param name="headerRowIndex">列标题行索引,从0开始</param>
        /// <returns></returns>
        private DataTable GetDataTableFromSheet(ISheet sheet, int headerRowIndex)
        {
            DataTable table = new DataTable();

            IRow headerRow = sheet.GetRow(headerRowIndex);

            ///获取excel 的列数
            int cellCount = headerRow.LastCellNum;


            // 根据Sheet为DataTable设置列 
            for (int i = 0; i < cellCount; i++)
            {
                if (headerRow.GetCell(i) == null || headerRow.GetCell(i).StringCellValue.Trim() == "")
                {
                    // 如果遇到第一个空列，则不再继续向后读取
                    cellCount = i;
                    break;
                }
                DataColumn column = new DataColumn(headerRow.GetCell(i).StringCellValue);
                table.Columns.Add(column);
            }

            //if (cellCount != 4)    // 如果标的结构不符合要求则提示导入文件错误
            //{
            //    //MessageBox.Show("该Excel数据异常，请确认导入的文件数据是否正确！");
            //    return null;
            //}


            // 获取sheet  的行数 
            int sheetCount = sheet.LastRowNum;
            for (int i = (headerRowIndex + 1); i <= sheetCount; i++)
            {
                try
                {
                    // 获取一行
                    IRow row = sheet.GetRow(i);
                    //如果遇到某行的第一个单元格的值为空，则不再继续向下读取
                    if (row != null && row.GetCell(0) != null)
                    {
                        // 读取sheet的一行到DataTable里面  
                        DataRow dataRow = table.NewRow();

                        for (int j = row.FirstCellNum; j < cellCount; j++)
                        {
                            dataRow[j] = row.GetCell(j).ToString();
                        }

                        table.Rows.Add(dataRow);
                    }
                }
                catch (Exception)
                {

                }

            }
            return table;
        }


        private static IWorkbook CreateWorkbook(bool isCompatible, dynamic stream)
        {
            if (isCompatible)
            {
                return new HSSFWorkbook(stream);
            }
            else
            {
                return new XSSFWorkbook(stream);
            }
        }

        private static bool GetIsCompatible(string filePath)
        {
            return filePath.EndsWith(".xls", StringComparison.OrdinalIgnoreCase);
        }

2.读取excel里面的图片

/// <summary>
        /// 从excel获取图片,由于excel存储图片的机制，只能根据excel中图片插入顺序导出
        /// </summary>
        /// <param name="filepath">文件路径</param>
        /// <param name="savepath">图片保存路径</param>
        /// <param name="listPath">返回保存的图表地址list</param>
        /// <returns>保存图片是否成功</returns>
        public  bool ExcelToImage(string filepath, string savepath, ref List<string> listPath)
        {
            if(!Directory.Exists(savepath))
            {
                Directory.CreateDirectory(savepath);
            }
            try
            {
                using (FileStream fsReader = File.OpenRead(filepath))
                {
                    HSSFWorkbook wk = new HSSFWorkbook(fsReader);
                    IList pictures = wk.GetAllPictures();
                    int i = 0;
                    foreach (HSSFPictureData pic in pictures)
                    {
                        //if (pic.Data.Length == 19504) //跳过不需要保存的图片，其中pic.data有图片长度
                        //    continue;
                        string ext = pic.SuggestFileExtension();//获取扩展名
                        string path = string.Empty;
                        if (ext.Equals("jpg"))
                        {
                            Image jpg = Image.FromStream(new MemoryStream(pic.Data));//从pic.Data数据流创建图片
                            path = Path.Combine(savepath, string.Format("pic{0}.jpg", i++));
                            jpg.Save(path);//保存
                        }
                        else if (ext.Equals("png"))
                        {
                            Image png = Image.FromStream(new MemoryStream(pic.Data));
                            path = Path.Combine(savepath, string.Format("pic{0}.png", i++));
                            png.Save(path);
                        }
                        else if (ext.Equals("jpeg"))
                        {
                            Image png = Image.FromStream(new MemoryStream(pic.Data));
                            path = Path.Combine(savepath, string.Format("pic{0}.png", i++));
                            png.Save(path);
                        }
                        if (!string.IsNullOrEmpty(path))
                            listPath.Add(path);
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("图片导出异常");
                return false;

            }
            Console.WriteLine("图片导出成功，共" + listPath.Count +"个图片");
            return true;
        }