NPOI读写Excel0307

 #region NPOI 操作 Excel 2007
         /// <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 filePath)
         {
             DataTable dt = new DataTable();
             using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
             {
                 XSSFWorkbook xssfworkbook = new XSSFWorkbook(fs);
                 ISheet sheet = xssfworkbook.GetSheetAt();

                 //表头
                 IRow header = sheet.GetRow(sheet.FirstRowNum);
                 List<int> columns = new List<int>();
                 for (int i = ; 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 + ; 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("Test");

             //表头
             IRow row = sheet.CreateRow();
             for (int i = ; i < dt.Columns.Count; i++)
             {
                 ICell cell = row.CreateCell(i);
                 cell.SetCellValue(dt.Columns[i].ColumnName);
             }

             //数据
             for (int i = ; i < dt.Rows.Count; i++)
             {
                 IRow row1 = sheet.CreateRow(i + );
                 for (int j = ; 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, , 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

         #region NPOI 操作 Excel 2003
         /// <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 filePath)
         {
             DataTable dt = new DataTable();
             using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
             {
                 HSSFWorkbook hssfworkbook = new HSSFWorkbook(fs);
                 ISheet sheet = hssfworkbook.GetSheetAt();

                 //表头
                 IRow header = sheet.GetRow(sheet.FirstRowNum);
                 List<int> columns = new List<int>();
                 for (int i = ; 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 + ; 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();
             for (int i = ; i < dt.Columns.Count; i++)
             {
                 ICell cell = row.CreateCell(i);
                 cell.SetCellValue(dt.Columns[i].ColumnName);
             }

             //数据
             for (int i = ; i < dt.Rows.Count; i++)
             {
                 IRow row1 = sheet.CreateRow(i + );
                 for (int j = ; 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, , 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

通过字符串Split就可以得到后缀

 private string MySubString(string s)
         {
             string[] str = s.Split('.');
             string temp = str[];
             return temp;
         }