Excel导入：

if (Path.GetExtension(filePath).ToLower() == ".xls".ToLower())
            {
                HSSFWorkbook hssfworkbook;
                try
                {
                    using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                    {

                        hssfworkbook = new HSSFWorkbook(file);
                    }
                }
                catch (Exception e)
                {
                    throw e;
                }

                ISheet sheet = hssfworkbook.GetSheetAt(0);
                System.Collections.IEnumerator rows = sheet.GetRowEnumerator();
                HSSFRow headerRow = (HSSFRow)sheet.GetRow(0);

                for (int j = 0; j < (sheet.GetRow(0).LastCellNum); j++)
                {
                    //SET EVERY COLUMN NAME
                    HSSFCell cell = (HSSFCell)headerRow.GetCell(j);

                    dt.Columns.Add(cell.ToString());
                }

                while (rows.MoveNext())
                {
                    IRow row = (HSSFRow)rows.Current;
                    DataRow dr = dt.NewRow();

                    if (row.RowNum == 0) continue;//The firt row is title,no need import

                    for (int i = 0; i < row.LastCellNum; i++)
                    {
                        if (i >= dt.Columns.Count)
                        {
                            break;
                        }

                        ICell cell = row.GetCell(i);

                        if ((i == 0) && (string.IsNullOrEmpty(cell.ToString()) == true))
                        {
                            break;
                        }

                        if (cell == null)
                        {
                            dr[i] = null;
                        }
                        else
                        {
                            dr[i] = cell.ToString();
                        }
                    }

                    dt.Rows.Add(dr);
                }
               
            }
            else
            {//.xlsx
                XSSFWorkbook hssfworkbook;
                try
                {
                    using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                    {

                        hssfworkbook = new XSSFWorkbook(file);
                    }
                }
                catch (Exception e)
                {
                    throw e;
                }

                ISheet sheet = hssfworkbook.GetSheetAt(0);
                System.Collections.IEnumerator rows = sheet.GetRowEnumerator();
                XSSFRow headerRow = (XSSFRow)sheet.GetRow(0);
 
                for (int j = 0; j < (sheet.GetRow(0).LastCellNum); j++)
                {
                    
                    XSSFCell cell = (XSSFCell)headerRow.GetCell(j);

                    dt.Columns.Add(cell.ToString());

                }

                while (rows.MoveNext())
                {
                    IRow row = (XSSFRow)rows.Current;
                    DataRow dr = dt.NewRow();

                    if (row.RowNum == 0) continue;

                    for (int i = 0; i < row.LastCellNum; i++)
                    {
                        if (i >= dt.Columns.Count)
                        {
                            break;
                        }

                        ICell cell = row.GetCell(i);

                        if ((i == 0) && (string.IsNullOrEmpty(cell.ToString()) == true))
                        {
                            break;
                        }

                        if (cell == null)
                        {
                            dr[i] = null;
                        }
                        else
                        {
                            dr[i] = cell.ToString();
                        }
                    }
                    dt.Rows.Add(dr);
                }
               
            }
            return dt;

        }