Play framework handle 206 Partial Content

   final long MAX_ALLOWED_CHUNK_SIZE = 15 * 1024 * 1024;
   final Pattern rangeMatcher = Pattern.compile("[^\\d]+(\\d+)[^\\d]+(\\d+)?");

    public Result download(String path) {
        String sanitizedPath;
        try {
            sanitizedPath = sanitizedUserInputPath(path == null ? "" : path);
        } catch(RuntimeException e) {
            return badRequest(e.toString());
        }

        if (!request().getHeaders().contains("Range")) {
            return ok(new java.io.File(sanitizedPath));
        }

        String rangeHeader =  request().getHeaders().get("Range").get();
        Matcher rangeValues = rangeMatcher.matcher(rangeHeader);
        if (!rangeValues.find()) {
            return badRequest("Missing range header");
        }

        long fileSize = new File(sanitizedPath).length();
        long start, end;
        if (rangeValues.group(1) != null) {
            start = Long.parseLong(rangeValues.group(1));
        } else {
            start = 0;
        }

        if (rangeValues.group(2) != null) {
            // -1 because byte array index starts at 0.
            end = Math.min(Long.parseLong(rangeValues.group(2)), MAX_ALLOWED_CHUNK_SIZE - 1);
        } else {
            end = Math.min(fileSize - 1, start + MAX_ALLOWED_CHUNK_SIZE - 1);
        }

        // get MIME type
        String mimeType;
        try {
            mimeType = Files.probeContentType(Paths.get(sanitizedPath));
        } catch (IOException e) {
            return badRequest("Unknown MIME type");
        }

        long contentLength = end - start + 1;
        String returnContentRange = String.format("bytes %d-%d/%d", start, end, fileSize);

        Source<ByteString, ?> source = FileIO.fromPath(Paths.get(sanitizedPath), (int) contentLength, start);

        return new Result(
                new ResponseHeader(206, ImmutableMap.of(
                    "Accept-Ranges", "bytes",
                    "Content-Range", returnContentRange  // Without this field, it won't work
                )),
                new HttpEntity.Streamed(source, Optional.of(contentLength), Optional.of(mimeType))
        );
    }