public static final String upload(String baseDir, MultipartFile file, String[] allowedExtension)
            throws FileSizeLimitExceededException, IOException, FileNameLengthLimitExceededException,
            InvalidExtensionException
    {   //判斷文件名長度是否過長
        int fileNamelength = Objects.requireNonNull(file.getOriginalFilename()).length();
        if (fileNamelength > FileUploadUtils.DEFAULT_FILE_NAME_LENGTH)
        {
            throw new FileNameLengthLimitExceededException(FileUploadUtils.DEFAULT_FILE_NAME_LENGTH);
        }
        //判斷文件的擴展類型是否合理
        assertAllowed(file, allowedExtension);
        //對文件名進行編碼
        String fileName = extractFilename(file);
        //獲取文件在本機的絕對地址
        String absPath = getAbsoluteFile(baseDir, fileName).getAbsolutePath();
        //將文件放到本機絕對地址
        file.transferTo(Paths.get(absPath));
        //返回文件名
        return getPathFileName(fileName);
    }
//比較重要的就是這個 他將會創(chuàng)建多級目錄 并且把文件保存到對應(yīng)的位置
private static final File getAbsoluteFile(String uploadDir, String fileName) throws IOException
    {
        File desc = new File(uploadDir + File.separator + fileName);

        if (!desc.exists())
        {
            if (!desc.getParentFile().exists())
            {
                desc.getParentFile().mkdirs();
            }
        }
        return desc.isAbsolute() ? desc : desc.getAbsoluteFile();
    }

@AutoConfiguration
public class DynamicThreadPool {

    /**
     * 初始化線程池
     *
     * @return
     */
    @Bean("fileThreadPool")
    private static ThreadPoolExecutor buildThreadPoolExecutor() {
        return new ThreadPoolExecutor(3,
                3,
                60,
                TimeUnit.SECONDS,
                new ResizableCapacityLinkedBlockIngQueue<Runnable>(10),
                new NamedThreadFactory("file-thread-"),
                new ThreadPoolExecutor.DiscardPolicy());
    }
}

 	@Autowired
    @Qualifier("fileThreadPool")
    private ThreadPoolExecutor fileThreadPool;

    /**
     * 實現(xiàn)多文件多線程上傳
     *
     * @param files 要上傳的文件
     * @return 返回戀愛日志信息
     */
    @ApiOperation(value = "多附件上傳-純附件上傳", notes = "多附件上傳")
    @ResponseBody
    @PostMapping("/uploadFiles")
    public R<LoveLogs> handleFileUpload(@RequestParam("files") MultipartFile[] files) {
        LoveLogs loveLogs = new LoveLogs();
        String[] urls = new String[files.length];
        CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<>();
        CountDownLatch countDownLatch = new CountDownLatch(files.length);
        for (int i = 0; i < files.length; i++) {
            try {
                 獲取文件名
                //String fileName = file.getOriginalFilename();
                 拼接文件保存路徑
                //String filePath = "D:/uploads/" + fileName;
                 保存文件到本地
                //file.transferTo(new File(filePath));
                MultipartFile file = files[i];
                //String url = sysFileService.uploadFile(file);
                //urls[i] = url;
                //TODO 使用CountDownLaunch或者ComplatableFuture或者Semaphore
                //來完成多線程的文件上傳
                fileThreadPool.submit(() -> {
                    try {
                        String s = sysFileService.uploadFile(file);
                        list.add(s);
                    } catch (Exception e) {
                        throw new RuntimeException(e);
                    } finally {
                        //表示一個文件已經(jīng)被完成
                        countDownLatch.countDown();
                    }
                });
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
        try {
            //阻塞直到所有的文件完成復(fù)制
            countDownLatch.await();
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }
        //統(tǒng)計每個文件的url
        String photoUrls = String.join(",", list);
        loveLogs.setUrls(photoUrls);
        //返回結(jié)果
        return R.ok(loveLogs);
    }

/**
     * 文件下載
     *
     * @param name     文件名稱
     * @param response 響應(yīng)流
     */
    @GetMapping("/download")
    public void download(@RequestParam String name, HttpServletResponse response) {
        //FileInputStream fis = null;
        //ServletOutputStream os = null;
        try (FileInputStream fis = new FileInputStream(new File(name));
             ServletOutputStream os = response.getOutputStream()) {
            //輸入流,通過輸入流讀取文件內(nèi)容
            //fis = new FileInputStream(new File( name));
            //輸出流,通過輸出流將文件寫回瀏覽器,在瀏覽器展示圖片
            //os = response.getOutputStream();
            //設(shè)置響應(yīng)的數(shù)據(jù)的格式
            response.setContentType("image/jpeg");
            int len = 0;
            byte[] buffre = new byte[1024 * 10];
            while ((len = fis.read(buffre)) != -1) {
                os.write(buffre, 0, len);
                os.flush();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }