从Minio断点续传资源，支持边下载边看

需求：客户端读取视频资源，边下载边读取
适用：minio文件服务器或其它本地服务器，oss文件服务器本身就支持，不需要此类方法
已解决：ios系统在资源过大的情况会出现异常。
public void getFileForRange(@PathVariable("fileId") String fileId,
                                OutputStream out,HttpServletRequest request, HttpServletResponse response) throws IOException {
        String filepath = String.format("%s/%s","存储文件路径",fileId);
        FileInputStream inputFileStream = null;
        BufferedOutputStream outputStream = null;
        try {
            File file = new File(filepath);
            if (!file.exists()) {
                // 禁止多线程同时下载视频文件
                try {
                    if(redisUtils.tryLock(CacheKey.VIDEO_CACHE_KEY + fileId)){
                        //mino获取文件并写在服务端
                        InputStream stream = fileBiz.get(fileId);
                        cn.hutool.core.io.FileUtil.writeFromStream(stream, file);
                    }
                }catch (Exception e){
                    log.error("下载文件失败:{}",e);
                }finally {
                    redisUtils.release(CacheKey.VIDEO_CACHE_KEY + fileId);
                }
            }

            long point = 0;
            long fileLength = file.length();
            long position_end = fileLength;

            inputFileStream = new FileInputStream(file);
            outputStream = new BufferedOutputStream(response.getOutputStream());
            response.reset();

            //设置支持断点
            response.setHeader("Accept-Ranges", "bytes");

            //获取断点位置
            String Range = request.getHeader("Range");
            if (Range != null) {
                response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
                String RangeFromTo = Range.replaceAll("bytes=", "");
                log.info("threadName: " + Thread.currentThread().getId() + " Range : " + RangeFromTo);
                String[] Ranges = RangeFromTo.split("-");
                point = Long.parseLong(Ranges[0]);

                if (2 == Ranges.length && !Ranges[1].equals("")) {
                    position_end = Long.parseLong(Ranges[1]);
                }
            }

            //写明要下载的文件的大小
            response.setHeader("Content-Length", Long.toString(position_end - point));
            log.info("threadName: " + Thread.currentThread().getId() + "point : " + point + " Content-Length : " + (position_end - point));

            //设置response的编码方式
            response.setContentType("application/x-msdownload");

            //设置断点续传回应头
            String contentRange = new StringBuffer("bytes ")
                    .append(point)
                    .append("-")
                    .append(fileLength - 1)
                    .append("/")
                    .append(fileLength)
                    .toString();

            if (point != 0) {
                // 断点续传的回应头：告诉改块插入的位置和文件的总大小
                // 格式：Content-Range: bytes [文件块的开始字节]-[文件块的结束字节 - 1]/[文件的总大小]
                contentRange = new StringBuffer("bytes ")
                        .append(point)
                        .append("-")
                        .append(position_end - 1)
                        .append("/")
                        .append(fileLength)
                        .toString();
                // 移动文件指针位置，断点处
                inputFileStream.skip(point);
            }
            response.setHeader("Accept-Ranges", "bytes");
            response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
            response.setContentType("video/mp4");
            // ios 默认不为添加
            response.setHeader("Content-Type", "video/mp4");
            response.setHeader("Content-Disposition", "inline;filename=" + filepath);
            response.setHeader("Content-Length", String.valueOf(position_end - point + 1));
            response.setHeader("Content-Range", "bytes " + position_end + "-" + point + "/" + file.length());
            response.setHeader("Content-Range", contentRange);

            long bytesWritten = 0;
            byte[] bytes = new byte[1024 * 4];
            int byteCount;

            long NeedWriten = position_end - point + 1;

            while (NeedWriten >= bytesWritten && (byteCount = inputFileStream.read(bytes)) != -1) {
                if (NeedWriten >= bytesWritten) {
                    long tTempWriten = (bytesWritten + byteCount) > NeedWriten ? (NeedWriten - bytesWritten) : byteCount;
                    outputStream.write(bytes, 0, (int) tTempWriten);
                    bytesWritten += tTempWriten;
                }
            }
        } catch (FileNotFoundException e) {
            log.error("读取文件失败：" + filepath + " FileNotFoundException happen : " + e + " URL : " + request.getRequestURL().toString());
        } catch (IOException e) {
            log.error("读取文件失败：" + filepath + " IOException hapepn : " + e + " URL : " + request.getRequestURL().toString());
        } finally {
            try {
                if (null != inputFileStream) {
                    inputFileStream.close();
                }
                if (null != outputStream) {
                    outputStream.close();
                }
            } catch (IOException e) {
                log.error("下载文件失败：" + filepath + " EofException happen : " + e);
            }
        }
    }

参考：Java断点下载_ZeroKoop的博客-CSDN博客