Java web文件下载断点续传

柔情只为你懂 2023-07-24 14:33 21阅读 0赞

### 一、下载文件请求  ###

@RequestMapping(value = "/file/download")
        @ResponseBody
        public Res download(HttpServletRequest request, HttpServletResponse response) {
    
    
            File file = new File(request.getParameter("fileName"));
            if (file.exists()) {
    
                String range = request.getHeader("Range");
                if (range != null && (range = range.trim()).length() > 0) {
                    Pattern rangePattern = Pattern.compile("^bytes=([0-9]+)-([0-9]+)?$");
                    Matcher matcher = rangePattern.matcher(range);
                    if (matcher.find()) {
                        Integer start = Integer.valueOf(matcher.group(1));
                        Integer end = 0;
                        String endStr = matcher.group(2);
                        if (endStr != null && (endStr = endStr.trim()).length() > 0)
                            end = Integer.valueOf(endStr);
    
                        downLoadByBreakpoint(file, start, end, response);
                        return null;
                    }
                }
    
                downLoadAll(file, response);
                return null;
            }
            
            return Res.fail("文件不存在");
    
        }

### 二、断点下载 ###

public void downLoadByBreakpoint(File file, long start, long end, HttpServletResponse response){
            OutputStream stream = null;
            RandomAccessFile fif = null;
            try {
                if (end <= 0) {
                    end = file.length() - 1;
                }
                stream = response.getOutputStream();
                response.reset();
                response.setStatus(206);
                response.setContentType("application/octet-stream");
                response.setHeader("Content-disposition", "attachment; filename=" + file.getName());
                response.setHeader("Content-Length", String.valueOf(end - start + 1));
                response.setHeader("Accept-Ranges", "bytes");
                response.setHeader("Content-Range", String.format("bytes %s-%s/%s", start, end, file.length()));
                fif = new RandomAccessFile(file, "r");
                fif.seek(start);
                long index = start;
                int d;
                byte[] buf = new byte[10240];
                while (index <= end && (d = fif.read(buf)) != -1) {
                    if (index + d > end) {
                        d = (int)(end - index + 1);
                    }
                    index += d;
                    stream.write(buf, 0, d);
                }
                stream.flush();
            } catch (Exception e) {
                try {
                    if (stream != null)
                        stream.close();
                    if (fif != null)
                        fif.close();
                } catch (Exception e11) {
                }
            }
        }

### 三、普通全量下载 ###

public void downLoadAll(File file, HttpServletResponse response){
            OutputStream stream = null;
            BufferedInputStream fif = null;
            try {
                stream = response.getOutputStream();
                response.reset();
                response.setContentType("application/octet-stream");
                response.setHeader("Content-disposition", "attachment; filename=" + file.getName());
                response.setHeader("Content-Length", String.valueOf(file.length()));
                fif = new BufferedInputStream(new FileInputStream(file));
                int d;
                byte[] buf = new byte[10240];
                while ((d = fif.read(buf)) != -1) {
                    stream.write(buf, 0, d);
                }
                stream.flush();
            } catch (Exception e) {
                try {
                    if (stream != null)
                        stream.close();
                    if (fif != null)
                        fif.close();
                } catch (Exception e11) {
                }
            }
        }