到WriteContextImpl写内容实现类的finish方法中，我们可以看到writeWorkbookHolder.getWorkbook().write(writeWorkbookHolder.getOutputStream()); 这句是重点，将写Excel持有容器中的内容流输出；之后就是关闭流，删除临时文件的过程
@Override public void finish() { WriteHandlerUtils.afterWorkbookDispose(this); if (writeWorkbookHolder == null) { return; } Throwable throwable = null; boolean isOutputStreamEncrypt = false; try { isOutputStreamEncrypt = doOutputStreamEncrypt07(); } catch (Throwable t) { throwable = t; } if (!isOutputStreamEncrypt) { try { // 重点 writeWorkbookHolder.getWorkbook().write(writeWorkbookHolder.getOutputStream()); writeWorkbookHolder.getWorkbook().close(); } catch (Throwable t) { throwable = t; } } try { Workbook workbook = writeWorkbookHolder.getWorkbook(); if (workbook instanceof SXSSFWorkbook) { ((SXSSFWorkbook)workbook).dispose(); } } catch (Throwable t) { throwable = t; } try { if (writeWorkbookHolder.getAutoCloseStream() && writeWorkbookHolder.getOutputStream() != null) { writeWorkbookHolder.getOutputStream().close(); } } catch (Throwable t) { throwable = t; } if (!isOutputStreamEncrypt) { try { doFileEncrypt07(); } catch (Throwable t) { throwable = t; } } try { if (writeWorkbookHolder.getTempTemplateInputStream() != null) { writeWorkbookHolder.getTempTemplateInputStream().close(); } } catch (Throwable t) { throwable = t; } clearEncrypt03(); if (throwable != null) { throw new ExcelGenerateException("Can not close IO", throwable); } if (LOGGER.isDebugEnabled()) { LOGGER.debug("Finished write."); } } 1.4. 文件上传它提供了一个接收InputStream的参数，之后和Excel读没多大区别
/** * 文件上传 * <p> * 1. 创建excel对应的实体对象 参照{@link UploadData} * <p> * 2. 由于默认异步读取excel，所以需要创建excel一行一行的回调监听器，参照{@link UploadDataListener} * <p> * 3. 直接读即可 */ @PostMapping("upload") @ResponseBody public String upload(MultipartFile file) throws IOException { EasyExcel.read(file.getInputStream(), UploadData.class, new UploadDataListener()).sheet().doRead(); return "success"; } 1.5. 文件下载写入提供参数OutputStream，其它和文件写入差不多
/** * 文件下载 * <p> * 1. 创建excel对应的实体对象 参照{@link DownloadData} * <p> * 2. 设置返回的 参数 * <p> * 3. 直接写，这里注意，finish的时候会自动关闭OutputStream,当然你外面再关闭流问题不大 */ @GetMapping("download") public void download(HttpServletResponse response) throws IOException { // 这里注意 有同学反应使用swagger 会导致各种问题，请直接用浏览器或者用postman response.setContentType("application/vnd.ms-excel"); response.setCharacterEncoding("utf-8"); // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系 String fileName = URLEncoder.encode("测试", "UTF-8"); response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".xlsx"); EasyExcel.write(response.getOutputStream(), DownloadData.class).sheet("模板").doWrite(data()); } 1.6. 读取技巧 1.6.1. Excel读取多页