HSSFCellStyle cellStyle_date = workbook.createCellStyle();
cellStyle_date.setAlignment(HSSFCellStyle.ALIGN_CENTER);
cellStyle_date.setDataFormat(HSSFDataFormat.getBuiltinFormat("m/d/yy h:mm"));
HSSFCellStyle cellStyle_timestamp = workbook.createCellStyle();
cellStyle_timestamp.setAlignment(HSSFCellStyle.ALIGN_CENTER);
cellStyle_timestamp.setDataFormat(HSSFDataFormat.getBuiltinFormat("m/d/yy h:mm"));
HSSFCellStyle cellStyle_decimal = workbook.createCellStyle();
cellStyle_decimal.setAlignment(HSSFCellStyle.ALIGN_RIGHT);