java 视频断点播放，实现无卡顿

背景：前端一般展示页面播放视频都是从头加载视频，这样会使用户体现很差，网速不好快进的话就会卡顿，加载太慢，为了 解决这一问题，后台给前端提供的接口需要实现断点下载的功能

@ApiOperation(value = "视频播放一方法", notes = "视频播放一方法")
    @GetMapping(value = "/preview")
    @ApiImplicitParams({
            @ApiImplicitParam(name = "url", value = "文件路径", required = true,paramType = "query")
    })
    @Override
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        // TODO Auto-generated method stub
        HttpServletRequest request=(HttpServletRequest)req;
        HttpServletResponse response=(HttpServletResponse)res;
        System.out.println(req.getParameter("url"));
        String path = addMinioUrl.getObPath(req.getParameter("url"));
        //String path="E:/video/111.mp4";
        RandomAccessFile targetFile = null;
        OutputStream outputStream = null;
        try {
            outputStream = response.getOutputStream();
            response.reset();
            //获取请求头中Range的值
            String rangeString = request.getHeader(HttpHeaders.RANGE);
 
            //打开文件
            File file = new File(path);
            if (file.exists()) {
                //使用RandomAccessFile读取文件
                targetFile = new RandomAccessFile(file, "r");
                long fileLength = targetFile.length();
                long requestSize = (int) fileLength;
                //分段下载视频
                if (StringUtils.hasText(rangeString)) {
                    //从Range中提取需要获取数据的开始和结束位置
                    long requestStart = 0, requestEnd = 0;
                    String[] ranges = rangeString.split("=");
                    if (ranges.length > 1) {
                        String[] rangeDatas = ranges[1].split("-");
                        requestStart = Integer.parseInt(rangeDatas[0]);
                        if (rangeDatas.length > 1) {
                            requestEnd = Integer.parseInt(rangeDatas[1]);
                        }
                    }
                    if (requestEnd != 0 && requestEnd > requestStart) {
                        requestSize = requestEnd - requestStart + 1;
                    }
                    //根据协议设置请求头
                    response.setHeader(HttpHeaders.ACCEPT_RANGES, "bytes");
                    response.setHeader(HttpHeaders.CONTENT_TYPE, "video/mp4");
                    if (!StringUtils.hasText(rangeString)) {
                        response.setHeader(HttpHeaders.CONTENT_LENGTH, fileLength + "");
                    } else {
                        long length;
                        if (requestEnd > 0) {
                            length = requestEnd - requestStart + 1;
                            response.setHeader(HttpHeaders.CONTENT_LENGTH, "" + length);
                            response.setHeader(HttpHeaders.CONTENT_RANGE, "bytes " + requestStart + "-" + requestEnd + "/" + fileLength);
                        } else {
                            length = fileLength - requestStart;
                            response.setHeader(HttpHeaders.CONTENT_LENGTH, "" + length);
                            response.setHeader(HttpHeaders.CONTENT_RANGE, "bytes " + requestStart + "-" + (fileLength - 1) + "/"
                                    + fileLength);
                        }
                    }
                    //断点传输下载视频返回206
                    response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
                    //设置targetFile，从自定义位置开始读取数据
                    targetFile.seek(requestStart);
                } else {
                    //如果Range为空则下载整个视频
                    response.setHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=test.mp4");
                    //设置文件长度
                    response.setHeader(HttpHeaders.CONTENT_LENGTH, String.valueOf(fileLength));
                }
 
                //从磁盘读取数据流返回
                byte[] cache = new byte[4096];
                try {
                    while (requestSize > 0) {
                        int len = targetFile.read(cache);
                        if (requestSize < cache.length) {
                            outputStream.write(cache, 0, (int) requestSize);
                        } else {
                            outputStream.write(cache, 0, len);
                            if (len < cache.length) {
                                break;
                            }
                        }
                        requestSize -= cache.length;
                    }
                } catch (IOException e) {
                    // tomcat原话。写操作IO异常几乎总是由于客户端主动关闭连接导致，所以直接吃掉异常打日志
                    //比如使用video播放视频时经常会发送Range为0- 的范围只是为了获取视频大小，之后就中断连接了
                    //log.info(e.getMessage());
                    //throw new RuntimeException(e);
                }
            } else {
                // throw new RuntimeException("文件路劲有误");
            }
            outputStream.flush();
        } catch (Exception e) {
            // e.printStackTrace();
            // throw new RuntimeException("文件传输错误");
        }finally {
            if(outputStream != null){
                try {
                    outputStream.close();
                } catch (IOException e) {
                    //e.printStackTrace();
                    // throw new RuntimeException("流释放错误");
 
                }
            }
            if(targetFile != null){
                try {
                    targetFile.close();
                } catch (IOException e) {
                    //e.printStackTrace();
                    //    throw new RuntimeException("文件流释放错误");
                }
            }
        }
 
    }

前端要安装视频插件，需要的小伙伴可以@我