将 POI SXSSFWorkbook 流式传输到 servlet 输出流

Question

我们正在构建一个 Spring Boot REST 端点，该端点生成一个大型 XLS 文件（可能包含约 100 万行）并提供下载。 当前的解决方案使用Apache POI 库的SXSSF API 来创建工作簿； 之后，我们将工作簿写入输出流，将流收集到一个字节数组中，然后提供这个以供下载。

当我们添加更多行时，如何流式传输工作簿的内容，以便我们不会将整个文件保存在内存中？

当前解决方案的代码

@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);
        }
    }

还尝试直接在 response.getOutputStream() 中写入工作簿内容，但文件以某种方式损坏。

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();

Answer 1

我刚刚使用您的代码作为模板并创建了运行良好的控制器

@RestController
public class XlsxController {

    @RequestMapping(path = "/download/xls", method = RequestMethod.GET, produces = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
    public void downloadXls(HttpServletResponse r) throws IOException {
        r.setHeader("Content-Description", "File Transfer");
        r.setHeader("Content-Disposition", "attachment; filename=justAFile.xlsx");
        r.setHeader("Content-Transfer-Encoding", "binary");
        r.setHeader("Connection", "Keep-Alive");

        try (SXSSFWorkbook w = getWorkbook()) {
            w.write(r.getOutputStream());
        }
    }

具有 100 万行的工作簿，权重超过 40 Mb

org.springframework:spring-webmvc:5.2.2.RELEASE
org.apache.poi:poi-ooxml:4.1.1