封装一个ExcelHelper,方便将Excel直接转成Datatable对象

  public class ExcelHelper
     {
         /// <summary>
         /// Excel转换成DataTable
         /// </summary>
         /// <param name="excelFilePath">excel文件路径</param>
         /// <param name="sheetNum">sheet序号</param>
         /// <param name="headerRowNum">标题列序号</param>
         /// <returns></returns>
         public static DataTable ExcelToDataTable(string excelFilePath,int sheetNum=,int headerRowNum=)
         {

             IWorkbook workbook;
             DataTable dt;
             string extension = Path.GetExtension(excelFilePath).ToLower();
             try
             {
                 using (FileStream fileStream = new FileStream(excelFilePath, FileMode.Open, FileAccess.Read))
                 {
                     if (extension == ".xlsx")
                     { workbook = new XSSFWorkbook(fileStream); }
                     else
                     { workbook = new HSSFWorkbook(fileStream); }
                     ISheet sheet = workbook.GetSheetAt(sheetNum);
                     dt = new DataTable(sheet.SheetName);
                     IRow headerRow = sheet.GetRow(headerRowNum);
                     string fieldName = "";
                     //ArrayList fieldArray = new ArrayList();
                     /*
                      增加标题列,author liwx 2016/08/25
                      */
                     for (int i = headerRow.FirstCellNum; i < headerRow.LastCellNum; i++)
                     {
                         if (headerRow.GetCell(i) != null)
                         {
                             fieldName = headerRow.GetCell(i).ToString().Trim();
                             //fieldArray.Add(fieldName);
                             DataColumn column = new DataColumn(fieldName);
                             dt.Columns.Add(column);
                         }
                         else
                         {
                             break;
                         }
                     }

                     DataRow dr;
                     IRow row;
                     ICell cell;
                     //short format;
                     for (int i = headerRowNum + ; i <= sheet.LastRowNum; i++)
                     {
                         row = sheet.GetRow(i);
                         if (row != null)
                         {
                             dr = dt.NewRow();
                             for (int j = headerRow.FirstCellNum; j < headerRow.LastCellNum; j++)
                             {
                                 cell=row.GetCell(j);
                                 if (cell != null)
                                 {
                                     //format = cell.CellStyle.DataFormat;
                                     //if (format == 14 || format == 31 || format == 57 || format == 58)
                                     //    dataRow[j] = cell.DateCellValue.ToString("yyyy/MM/dd");//日期转化格式如需要可解开
                                     dr[j] = cell.ToString().Trim() == "" ? null : cell.ToString().Trim();
                                 }
                                 else
                                 {
                                     dr[j] = null;
                                 }
                             }
                             dt.Rows.Add(dr);
                         }
                     }
                 }
             }
             catch (Exception ex)
             {
                 throw ex;
             }
             return dt;
         }
         /// <summary>
         /// Excel转换成DataTable
         /// </summary>
         /// <param name="excelFilePath">excel文件路径</param>
         /// <param name="sheetName">sheet名称</param>
         /// <param name="headerRowNum">标题列序号</param>
         /// <returns></returns>
         public static DataTable ExcelToDataTable(string excelFilePath, string sheetName, int headerRowNum = )
         {

             IWorkbook workbook;
             DataTable dt;
             string extension = Path.GetExtension(excelFilePath).ToLower();
             try
             {
                 using (FileStream fileStream = new FileStream(excelFilePath, FileMode.Open, FileAccess.Read))
                 {
                     if (extension == ".xlsx")
                     { workbook = new XSSFWorkbook(fileStream); }
                     else
                     { workbook = new HSSFWorkbook(fileStream); }
                     ISheet sheet;
                     //如果有指定工作表名称
                     if (!string.IsNullOrEmpty(sheetName))
                     {
                         sheet = workbook.GetSheet(sheetName);
                         //如果没有找到指定的sheetName对应的sheet，则尝试获取第一个sheet
                         if (sheet == null)
                         {
                             sheet = workbook.GetSheetAt();
                         }
                     }
                     else
                     {
                         //如果没有指定的sheetName，则尝试获取第一个sheet
                         sheet = workbook.GetSheetAt();
                     }

                     dt = new DataTable(sheet.SheetName);
                     IRow headerRow = sheet.GetRow(headerRowNum);
                     string fieldName = "";
                     //ArrayList fieldArray = new ArrayList();
                     /*
                      增加标题列,author liwx 2016/08/25
                      */
                     for (int i = headerRow.FirstCellNum; i < headerRow.LastCellNum; i++)
                     {
                         if (headerRow.GetCell(i) != null)
                         {
                             fieldName = headerRow.GetCell(i).ToString().Trim();
                             //fieldArray.Add(fieldName);
                             DataColumn column = new DataColumn(fieldName);
                             dt.Columns.Add(column);
                         }
                         else
                         {
                             break;
                         }
                     }

                     DataRow dr;
                     IRow row;
                     ICell cell;
                     //short format;
                     for (int i = headerRowNum + ; i <= sheet.LastRowNum; i++)
                     {
                         row = sheet.GetRow(i);
                         if (row != null)
                         {
                             dr = dt.NewRow();
                             for (int j = headerRow.FirstCellNum; j < headerRow.LastCellNum; j++)
                             {
                                 cell = row.GetCell(j);
                                 if (cell != null)
                                 {
                                     //format = cell.CellStyle.DataFormat;
                                     //if (format == 14 || format == 31 || format == 57 || format == 58)
                                     //    dataRow[j] = cell.DateCellValue.ToString("yyyy/MM/dd");//日期转化格式如需要可解开
                                     dr[j] = cell.ToString().Trim() == "" ? null : cell.ToString().Trim();
                                 }
                                 else
                                 {
                                     dr[j] = null;
                                 }
                             }
                             dt.Rows.Add(dr);
                         }
                     }
                 }
             }
             catch (Exception ex)
             {
                 throw ex;
             }
             return RemoveEmpty(dt);
         }
         /// <summary>
         /// 获取Excel里Sheet总数
         /// </summary>
         /// <param name="excelFilePath"></param>
         /// <returns></returns>
         public static int GetExcelSheetTotal(string excelFilePath)
         {
             IWorkbook workbook;
             DataTable dt;
             string extension = Path.GetExtension(excelFilePath).ToLower();
             try
             {
                 using (FileStream fileStream = new FileStream(excelFilePath, FileMode.Open, FileAccess.Read))
                 {
                     if (extension == ".xlsx")
                     { workbook = new XSSFWorkbook(fileStream); }
                     else
                     { workbook = new HSSFWorkbook(fileStream); }
                     return workbook.NumberOfSheets;
                 }
             }
             catch (Exception ex)
             {
                 throw ex;
             }
         }

         /// <summary>
         /// 将datatable导入到exel
         /// </summary>
         /// <param name="datatemp"></param>
         /// <param name="fileName"></param>
         ///<param name="removeEmpty">是否去除所有值都为空的列</param>
         /// <returns></returns>
         public static int DataTableToExcel(DataTable datatemp, string fileName,bool removeEmpty=true)
         {
             DataTable data = removeEmpty? RemoveEmpty(datatemp): datatemp;
             bool isColumnWritten = true;
             int i = ;
             int j = ;
             int count = ;
             ISheet sheet = null;
             IWorkbook workbook = null;
             using (FileStream fs = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.ReadWrite))
             {
                 if (fileName.IndexOf(".xlsx") > ) // 2007版本
                     workbook = new XSSFWorkbook();
                 else if (fileName.IndexOf(".xls") > ) // 2003版本
                     workbook = new HSSFWorkbook();

                 try
                 {
                     if (workbook != null)
                     {
                         sheet = workbook.CreateSheet("Sheet1");
                     }
                     else
                     {
                         return -;
                     }

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

                     for (i = ; i < data.Rows.Count; ++i)
                     {
                         IRow row = sheet.CreateRow(count);
                         for (j = ; j < data.Columns.Count; ++j)
                         {
                             row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                         }
                         ++count;
                     }
                     workbook.Write(fs); //写入到excel
                     return count;
                 }
                 catch (Exception ex)
                 {
                     Console.WriteLine("Exception: " + ex.Message);
                     return -;
                 }
             }
         }

         /// <summary>
         /// Excel导出成内存流
         /// </summary>
         /// <param name="data"></param>
         /// <returns></returns>
         public static MemoryStream DataTableToExcel(DataTable data)
         {
             bool isColumnWritten = true;
             int i = ;
             int j = ;
             int count = ;
             IWorkbook workbook =new HSSFWorkbook();
             try
             {
                 //添加一个sheet
                 ISheet sheet = workbook.CreateSheet("Sheet1");
                 //将数据逐步写入sheet1各个行
                 if (isColumnWritten == true) //写入DataTable的列名
                 {
                     IRow row = sheet.CreateRow();
                     for (j = ; j < data.Columns.Count; ++j)
                     {
                         row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
                     }
                     count = ;
                 }
                 else
                 {
                     count = ;
                 }

                 for (i = ; i < data.Rows.Count; ++i)
                 {
                     IRow row = sheet.CreateRow(count);
                     for (j = ; j < data.Columns.Count; ++j)
                     {
                         row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                     }
                     ++count;
                 }
                 // 写入到客户端
                 MemoryStream ms = new System.IO.MemoryStream();
                 workbook.Write(ms);
                 ms.Seek(, SeekOrigin.Begin);
                 return ms;
             }
             catch (Exception ex)
             {
                 throw ex;
                 Console.WriteLine("Exception: " + ex.Message);
                 return null;
             }
         }

         /// <summary>
         /// Excel导出成内存流
         /// </summary>
         /// <param name="data"></param>
         /// <returns></returns>
         public static MemoryStream DataTableToExcel(List<DataTable> dtList,List<string> nameList)
         {
             IWorkbook workbook = new HSSFWorkbook();
             try
             {
                 var data = dtList[];
                 for (var i=;i<dtList.Count();i++) {
                     ISheet sheet=string.IsNullOrWhiteSpace(nameList[i]) ?workbook.CreateSheet("Sheet"+(i+)):workbook.CreateSheet(nameList[i]);
                       WriteSheet(dtList[i],sheet);
                 }
                 // 写入到客户端
                 MemoryStream ms = new System.IO.MemoryStream();
                 workbook.Write(ms);
                 ms.Seek(, SeekOrigin.Begin);
                 return ms;
             }
             catch (Exception ex)
             {
                 throw ex;
                 Console.WriteLine("Exception: " + ex.Message);
                 return null;
             }
         }

         private static void WriteSheet(DataTable data,ISheet sheet, bool isColumnWritten=true) {
             int i = ;
             int j = ;
             int count = ;
             //将数据逐步写入sheet1各个行
             if (isColumnWritten == true) //写入DataTable的列名
             {
                 IRow row = sheet.CreateRow();
                 for (j = ; j < data.Columns.Count; ++j)
                 {
                     row.CreateCell(j).SetCellValue(data.Columns[j].ColumnName);
                 }
                 count = ;
             }
             else
             {
                 count = ;
             }

             for (i = ; i < data.Rows.Count; ++i)
             {
                 IRow row = sheet.CreateRow(count);
                 for (j = ; j < data.Columns.Count; ++j)
                 {
                     row.CreateCell(j).SetCellValue(data.Rows[i][j].ToString());
                 }
                 ++count;
             }

         }
         /// <summary>
         /// 去除空行
         /// </summary>
         /// <param name="dtr"></param>
         /// <returns></returns>
         protected static DataTable RemoveEmpty(DataTable dtr)
         {
             DataTable dt = dtr;
             List<DataRow> removelist = new List<DataRow>();
             for (int i = ; i < dt.Rows.Count; i++)
             {
                 bool IsNull = true;
                 for (int j = ; j < dt.Columns.Count; j++)
                 {
                     if (!string.IsNullOrEmpty(dt.Rows[i][j].ToString().Trim()))
                     {
                         IsNull = false;
                     }
                 }
                 if (IsNull)
                 {
                     removelist.Add(dt.Rows[i]);
                 }
             }
             for (int i = ; i < removelist.Count; i++)
             {
                 dt.Rows.Remove(removelist[i]);
             }
             return dt;
         }
     }