java下载文件文件内容为空

Question

java下载文件接口输出文件内容为空

如果不用javaresponse.getOutpuStream，而是new一个FileOutputStream，写死为本地路径，那么输出的文件可以正常查看，一点问题没有。可是下面的代码下载的文件，如果是图片，查看的时候提示不支持，pdf格式有页数，内容是空白的，文本格式也是空白的。换过ContentType也没解决，也试过直接write读回来的字节数组也没用。并且控制台并没有报错。希望各位朋友能够指点一二，不胜感激

public void downloadAnnexFile(String annexId, HttpServletRequest request, HttpServletResponse response){
        logger.info("进入service");
        RDDataAnnexBO annexInfo = rdDataAnnexDao.selectAnnexInfoById(annexId);
        logger.info("附件对象：" + annexInfo.toString());
        if(annexInfo == null){
            return;
        }
        //文件名转义回原文展示给用户下载
        String fileName = unescapeHtml4ByString(annexInfo.getFileName());
        logger.info("转义回原文的文件名：" + fileName);
        ByteArrayInputStream byteArrayInputStream = null;
        String downloadFileName = "";
        OutputStream outputStream = null;
        try {
            response.setContentType("application/octet-stream");
            String userAgent = request.getHeader("User-Agent");
            boolean isMSIE = ((userAgent != null && userAgent.contains("MSIE")) ||
                    (null != userAgent && (userAgent.contains("like Gecko") && !userAgent.contains("Safari"))) ||
                    (userAgent != null && userAgent.contains("Edge")));
            if (isMSIE) {
                downloadFileName = URLEncoder.encode(fileName + annexInfo.getFileSuffix(), "UTF-8");
            } else {
                downloadFileName = new String((fileName + annexInfo.getFileSuffix()).getBytes(StandardCharsets.UTF_8), StandardCharsets.ISO_8859_1);
            }
            response.setHeader("Content-disposition", String.format("attachment; filename=\"%s\"", downloadFileName));
            byte[] base = hdfsBucketDubboService.readStreamFileToHdfs(annexInfo.getAnnex(), "/BLM/RD");
            byteArrayInputStream = new ByteArrayInputStream(base);
            outputStream = response.getOutputStream();
            byte[] content = new byte[1024];
            int length = 0;
            while ((length = byteArrayInputStream.read(content)) != -1) {
                outputStream.write(content, 0, length);
            }
        } catch (Exception e) {
            logger.error("下载HDFS文件异常", e);
        } finally {
            try {
                if (outputStream != null) {
                    outputStream.flush();
                    outputStream.close();
                }
                if (byteArrayInputStream != null) {
                    byteArrayInputStream.close();
                }
            } catch (Exception e) {
                logger.error("流关闭异常:", e);
            }
        }
        logger.info("service完成");
    }

Answer 1

望采纳！！！

先调用 byteArrayInputstream 的 close，然后再调用 outputstream 的 flush 和 close 方法。。