Java 实现的断点下载

/** * @desc 断点下载工具方法 * @param request * @param response * @param fileLength * @param contentType * @param fileName * @param fileId */ public static void resumeDownload(HttpServletRequest request, HttpServletResponse response, Long fileLength, String contentType, String fileName, String fileId) { ServletOutputStream out = null; response.reset(); // 记录断点续传的开始点 long pos = 0; if (null != request.getHeader("Range")) { response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT); try { pos = Long.parseLong(request.getHeader("Range") .replaceAll("bytes=", "").replaceAll("-.*", "")); } catch (NumberFormatException e) { LOGGER.error(e.getMessage(), e); pos = 0; } String contentRange = new StringBuffer("bytes ").append(pos + "") .append("-").append((fileLength.intValue() - 1) + "") .append("/").append(fileLength.intValue() + "").toString(); response.setHeader("Content-Range", contentRange); } response.setHeader("Accept-Ranges", "bytes"); response.setHeader("Content-Length", String.valueOf(fileLength.intValue() - pos)); response.setCharacterEncoding("UTF-8"); response.setContentType(contentType); response.setHeader("Content-disposition", "attachment;filename=\"" + fileName + "\""); try { out = response.getOutputStream(); } catch (IOException e) { LOGGER.error(e.getMessage(), e); } // 断点下载 CloseableHttpClient httpClient = HttpClients.createDefault(); HttpPost httpPost = new HttpPost(SysConf.getString("fezo.download.url")); List<NameValuePair> nvps = new ArrayList<NameValuePair>(); nvps.add(new BasicNameValuePair(SysConf.getString("fezo.download.param"), fileId)); HttpResponse httpResponse = null; BufferedInputStream input = null; try { httpPost.setEntity(new UrlEncodedFormEntity(nvps)); httpPost.setHeader("Range", "bytes=" + pos + "-"); httpResponse = httpClient.execute(httpPost); input = new BufferedInputStream(httpResponse.getEntity().getContent()); byte[] buffer = new byte[CommonConstants.BUFFER_SIZE]; int len = -1; while ((len = input.read(buffer)) != -1) { out.write(buffer, 0, len); } out.flush(); out.close(); input.close(); } catch (UnsupportedEncodingException e) { LOGGER.error(e.getMessage(), e); } catch (ClientProtocolException e) { LOGGER.error(e.getMessage(), e); } catch (IOException e) { // 可以忽略这个异常，有可能是用户暂停下载，或者迅雷等下载工具分块下载 } finally { try { if (httpClient != null) httpClient.close(); } catch(IOException e) { LOGGER.error(e.getMessage(), e); } } }