读取EXCEL

            using (FileStream fs = new FileStream(inputFile, FileMode.Open, FileAccess.Read))
            {
                HSSFWorkbook workbook = new HSSFWorkbook(fs);
                HSSFSheet sheet1 = (HSSFSheet)workbook.GetSheetAt(0);


                using (FileStream csv = new FileStream(outputFile, FileMode.Create, FileAccess.Write))
                {
                    using (StreamWriter write = new StreamWriter(csv, Encoding.UTF8))
                    {
                        for (int i = sheet1.FirstRowNum; i < sheet1.LastRowNum; i++)
                        {
                            HSSFRow row = (HSSFRow)sheet1.GetRow(i);
                            if (row == null)
                                continue;
                            string content = "";
                            for (int j = row.FirstCellNum; j < row.LastCellNum; j++)
                            {
                                HSSFCell cell = (HSSFCell)row.GetCell(j);
                                if (cell == null)
                                    continue;
                                content += cell.ToString().Replace("\n", "") + ",";
                            }
                            content = content.Substring(0, content.Length - 1);
                            write.WriteLine(content);
                        }

                    }

                }