I think you can’t due to the Excel format. SXSSF creates temporary files and does not need to keep everything in memory. I recommend though to activate compression for those as they are heavy uncompressed
> Am 13.01.2020 um 11:19 schrieb Ramona Petricu > <ramona.petr...@metrosystems.net>: > > Hi, > > We are building a Spring boot REST endpoint that generates a large XLS file > (may contain ~ 1mil lines) and provides it for download. > The current solution uses the SXSSF API of Apache POI library for creating > the workbook; > after that we write the workbook to an output stream, collect the stream in > to an array of bytes and then provide this one for download. > > How could the content of the workbook be streamed, as we are adding more > rows, so that we don't keep the entire file in memory ? > I have found in the list of messages this answer > https://lists.apache.org/thread.html/ee085ea108af4f0db4b7b5c90a3558a4974f96ee908c7d254155ecd6%40%3Cuser.poi.apache.org%3E > Is it still up to date? Is this the way for doing the streaming or meanwhile > something has changed and we could do it directly from the memory? > > Code for current solution > > @RequestMapping(path = "/download/xls", method = RequestMethod.GET, produces > = org.springframework.http.MediaType.APPLICATION_OCTET_STREAM_VALUE) > public ResponseEntity<InputStreamResource> downloadXls(HttpServletResponse > response, XlsRequest request) throws FileNotFoundException, > InternalServerErrorException { > > byte[] data = downloadIssuesAsExcel(response, request); > > HttpHeaders headers = new HttpHeaders(); > headers.add("Content-Description", "File Transfer"); > headers.add("Content-Disposition", "attachment; filename=justAFile.xlsx"); > headers.add("Content-Transfer-Encoding", "binary"); > headers.add("Connection", "Keep-Alive"); > headers.setContentType( > org.springframework.http.MediaType.parseMediaType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")); > InputStreamResource isr = new InputStreamResource(new > ByteArrayInputStream(data)); > return > ResponseEntity.ok().contentLength(data.length).headers(headers).body(isr); > } > > public byte[] downloadIssuesAsExcel(HttpServletResponse response, XlsRequest > request) > throws InternalServerErrorException { > try { > SXSSFWorkbook workbook = createExcel(request, response); > ByteArrayOutputStream stream = new ByteArrayOutputStream(); > workbook.write(stream); > workbook.dispose(); > workbook.close(); > stream.close(); > return stream.toByteArray(); > } catch (Exception e) { > throw new InternalServerErrorException("IO exception while downloading XLS > file", e); > } > } > > Also tried to write the workbook content directly in the > response.getOutputStream() but the file gets corrupted somehow. > > response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"); > > response.setHeader("Content-Description", "File Transfer"); > response.setHeader("Content-Disposition", "attachment; filename=" + > issueDataService.getExcelName(request)); > response.setHeader("Content-Transfer-Encoding", "binary"); > response.setHeader("Connection", "Keep-Alive"); > > SXSSFWorkbook workbook = createExcel(request, response); > workbook.write(response.getOutputStream()); > workbook.dispose(); > workbook.close(); > > Thank you! > > --------------------------------------------------------------------- > To unsubscribe, e-mail: user-unsubscr...@poi.apache.org > For additional commands, e-mail: user-h...@poi.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@poi.apache.org For additional commands, e-mail: user-h...@poi.apache.org
