关于SpringBoot大文件RestTemplate下载解决方案

关于SpringBoot大文件RestTemplate-解决方案

近期基于项目上使用到的RestTemplate-文件流，遇到1G以上的大文件，-需要3-4分钟，因为调用API接口没有做分片与多线程， 文件流全部采用同步方式加载，性能很慢。最近结合网上案例及自己总结，写了一个分片-tuling/fileServer项目： 1.包含同步-文件流在浏览器加载输出相关代码； 2.包含分片多线程-分片文件及合并文件相关代码；

另外在DownloadThread项目中使用代码完成了一个远程RestUrl请求去获取一个远端资源大文件进行多线程分片- 到本地的一个案例，可以-一些诸如.mp4/.avi等视频类大文件。相关代码也一并打包上传。

同步-，支持分片-Range主要代码：

@Controller

public 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- 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-

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("-完成");

}finally {

if (is != null){

is.close();

}

if (os != null){

os.close();

}

}

}

}

多线程分片-分片文件，-完成之后合并分片主要代码：

@RestController

public 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() {

// 探测-

FileInfo fileInfo = download(0, 10, -1, null);

if (fileInfo != null) {

long pages = fileInfo.fSize / PER_PAGE;

for (long i = 0; i <= pages; i++) {

Future future = taskExecutor.submit(new DownloadThread(i * PER_PAGE, (i + 1) * PER_PAGE - 1, i, fileInfo.fName));

if (!future.isCancelled()) {

http:// 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.fNaKmQKjomme = fName;

}

}

/**

* 根据开始位置/结束位置

* 分片-文件，临时存储文件分片

* 文件大小=结束位置-开始位置

*

* @return

*/

private FileInfo download(long start, long end, long page, String fName) {

File dirhttp:// = new File(DOWN_PATH);

if (!dir.exists()) {

dir.mkdirs();

}

// 断点-

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();

// 最后一个分片

if (end - Long.parseLong(fSize) > 0) {

// 开始合并文件

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();

}

}

/**

* 获取远程文件尺寸

*/

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服务器响应错误!");

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 {

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);

}

}

}

代码都在本地亲测（已修复Bug）可用，目前比较欠缺的是没有实现在分片-时对应浏览器进行-展示，需要暂存在本地磁盘目录。 目前将代码开源，希望能有更好解决方案的Coder Fork支持！也欢迎Star捧场。

博文参考了图灵学院相关的分片-案例教程，并修改了部分代码实现：

WebUploader--基于SpringBoot搭建，java文件上传-高阶实战

本文代码已上传至github：

BurstDownload

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