近期基于項目上使用到的RestTemplate下載文件流，遇到1G以上的大文件，下載需要3-4分鐘，因為調(diào)用API接口沒有做分片與多線程， 文件流全部采用同步方式加載，性能很慢。最近結(jié)合網(wǎng)上案例及自己總結(jié)，寫了一個分片下載tuling/fileServer項目： 1.包含同步下載文件流在瀏覽器加載輸出相關(guān)代碼； 2.包含分片多線程下載分片文件及合并文件相關(guān)代碼；
另外在DownloadThread項目中使用代碼完成了一個遠(yuǎn)程RestUrl請求去獲取一個遠(yuǎn)端資源大文件進(jìn)行多線程分片下載 到本地的一個案例，可以下載一些諸如.mp4/.avi等視頻類大文件。相關(guān)代碼也一并打包上傳。
同步下載，支持分片下載Range主要代碼：
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@Controllerpublic class DownLoadController { private static final String UTF8 = "UTF-8"; @RequestMapping("/download") public void downLoadFile(HttpServletRequest request, HttpServletResponse response) throws IOException { File file = new File("D:\\DevTools\\ideaIU-2021.1.3.exe"); response.setCharacterEncoding(UTF8); InputStream is = null; OutputStream os = null; try { // 分片下載 Range表示方式 bytes=100-1000 100- long fSize = file.length(); response.setContentType("application/x-download"); String fileName = URLEncoder.encode(file.getName(), UTF8); response.addHeader("Content-Disposition", "attachment;filename=" + fileName); // 支持分片下載 response.setHeader("Accept-Range", "bytes"); response.setHeader("fSize", String.valueOf(fSize)); response.setHeader("fName", fileName); long pos = 0, last = fSize - 1, sum = 0; if (null != request.getHeader("Range")) { response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT); String numberRange = request.getHeader("Range").replaceAll("bytes=", ""); String[] strRange = numberRange.split("-"); if (strRange.length == 2) { pos = Long.parseLong(strRange[0].trim()); last = Long.parseLong(strRange[1].trim()); if (last > fSize-1) { last = fSize - 1; } } else { pos = Long.parseLong(numberRange.replaceAll("-", "").trim()); } } long rangeLength = last - pos + 1; String contentRange = new StringBuffer("bytes").append(pos).append("-").append(last).append("/").append(fSize).toString(); response.setHeader("Content-Range", contentRange); response.setHeader("Content-Length", String.valueOf(rangeLength)); os = new BufferedOutputStream(response.getOutputStream()); is = new BufferedInputStream(new FileInputStream(file)); is.skip(pos); byte[] buffer = new byte[1024]; int length = 0; while (sum < rangeLength) { int readLength = (int) (rangeLength - sum); length = is.read(buffer, 0, (rangeLength - sum) <= buffer.length ? readLength : buffer.length); sum += length; os.write(buffer,0, length); } System.out.println("下載完成"); }finally { if (is != null){ is.close(); } if (os != null){ os.close(); } } }} |
多線程分片下載分片文件，下載完成之后合并分片主要代碼：
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@RestControllerpublic class DownloadClient { private static final Logger LOGGER = LoggerFactory.getLogger(DownloadClient.class); private final static long PER_PAGE = 1024L * 1024L * 50L; private final static String DOWN_PATH = "F:\\fileItem"; ExecutorService taskExecutor = Executors.newFixedThreadPool(10); @RequestMapping("/downloadFile") public String downloadFile() { // 探測下載 FileInfo fileInfo = download(0, 10, -1, null); if (fileInfo != null) { long pages = fileInfo.fSize / PER_PAGE; for (long i = 0; i <= pages; i++) { Future<FileInfo> future = taskExecutor.submit(new DownloadThread(i * PER_PAGE, (i + 1) * PER_PAGE - 1, i, fileInfo.fName)); if (!future.isCancelled()) { try { fileInfo = future.get(); } catch (InterruptedException | ExecutionException e) { e.printStackTrace(); } } } return System.getProperty("user.home") + "\\Downloads\\" + fileInfo.fName; } return null; } class FileInfo { long fSize; String fName; public FileInfo(long fSize, String fName) { this.fSize = fSize; this.fName = fName; } } /** * 根據(jù)開始位置/結(jié)束位置 * 分片下載文件，臨時存儲文件分片 * 文件大小=結(jié)束位置-開始位置 * * @return */ private FileInfo download(long start, long end, long page, String fName) { File dir = new File(DOWN_PATH); if (!dir.exists()) { dir.mkdirs(); } // 斷點下載 File file = new File(DOWN_PATH, page + "-" + fName); if (file.exists() && page != -1 && file.length() == PER_PAGE) { return null; } try { HttpClient client = HttpClients.createDefault(); HttpGet httpGet = new HttpGet("http://127.0.0.1:8080/download"); httpGet.setHeader("Range", "bytes=" + start + "-" + end); HttpResponse response = client.execute(httpGet); String fSize = response.getFirstHeader("fSize").getValue(); fName = URLDecoder.decode(response.getFirstHeader("fName").getValue(), "UTF-8"); HttpEntity entity = response.getEntity(); InputStream is = entity.getContent(); FileOutputStream fos = new FileOutputStream(file); byte[] buffer = new byte[1024]; int ch; while ((ch = is.read(buffer)) != -1) { fos.write(buffer, 0, ch); } is.close(); fos.flush(); fos.close(); // 最后一個分片 if (end - Long.parseLong(fSize) > 0) { // 開始合并文件 mergeFile(fName, page); } return new FileInfo(Long.parseLong(fSize), fName); } catch (IOException e) { e.printStackTrace(); } return null; } private void mergeFile(String fName, long page) { File file = new File(DOWN_PATH, fName); try { BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream(file)); for (long i = 0; i <= page; i++) { File tempFile = new File(DOWN_PATH, i + "-" + fName); while (!file.exists() || (i != page && tempFile.length() < PER_PAGE)) { try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } byte[] bytes = FileUtils.readFileToByteArray(tempFile); os.write(bytes); os.flush(); tempFile.delete(); } File testFile = new File(DOWN_PATH, -1 + "-null"); testFile.delete(); os.flush(); os.close(); } catch (IOException e) { e.printStackTrace(); } } /** * 獲取遠(yuǎn)程文件尺寸 */ private long getRemoteFileSize(String remoteFileUrl) throws IOException { long fileSize = 0; HttpURLConnection httpConnection = (HttpURLConnection) new URL(remoteFileUrl).openConnection(); //使用HEAD方法 httpConnection.setRequestMethod("HEAD"); int responseCode = httpConnection.getResponseCode(); if (responseCode >= 400) { LOGGER.debug("Web服務(wù)器響應(yīng)錯誤!"); return 0; } String sHeader; for (int i = 1;; i++) { sHeader = httpConnection.getHeaderFieldKey(i); if (sHeader != null && sHeader.equals("Content-Length")) { LOGGER.debug("文件大小ContentLength:" + httpConnection.getContentLength()); fileSize = Long.parseLong(httpConnection.getHeaderField(sHeader)); break; } } return fileSize; } class DownloadThread implements Callable<FileInfo> { long start; long end; long page; String fName; public DownloadThread(long start, long end, long page, String fName) { this.start = start; this.end = end; this.page = page; this.fName = fName; } @Override public FileInfo call() { return download(start, end, page, fName); } }} |
代碼都在本地親測（已修復(fù)Bug）可用，目前比較欠缺的是沒有實現(xiàn)在分片下載時對應(yīng)瀏覽器進(jìn)行下載展示，需要暫存在本地磁盤目錄。 目前將代碼開源，希望能有更好解決方案的Coder Fork支持！也歡迎Star捧場。
博文參考了圖靈學(xué)院相關(guān)的分片下載案例教程，并修改了部分代碼實現(xiàn)：
WebUploader--基于SpringBoot搭建，Java文件上傳下載高階實戰(zhàn)
本文代碼已上傳至GitHub：
到此這篇關(guān)于SpringBoot大文件RestTemplate下載解決方案的文章就介紹到這了,更多相關(guān)SpringBoot RestTemplate下載內(nèi)容請搜索服務(wù)器之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持服務(wù)器之家！
原文鏈接：https://www.cnblogs.com/yif0118/p/15456666.html
