private DownloadResult download()

in src/main/java/com/aliyun/oss/internal/OSSDownloadOperation.java [517:585]
57 lines of code
8 McCabe index (conditional complexity)

    private DownloadResult download(DownloadCheckPoint downloadCheckPoint, DownloadFileRequest downloadFileRequest)
            throws Throwable {
        DownloadResult downloadResult = new DownloadResult();
        ArrayList<PartResult> taskResults = new ArrayList<PartResult>();
        ExecutorService service = Executors.newFixedThreadPool(downloadFileRequest.getTaskNum());
        ArrayList<Future<PartResult>> futures = new ArrayList<Future<PartResult>>();
        List<Task> tasks = new ArrayList<Task>();
        ProgressListener listener = downloadFileRequest.getProgressListener();

        // Compute the size of data pending download.
        long completedLength = 0;
        long contentLength = 0;
        for (int i = 0; i < downloadCheckPoint.downloadParts.size(); i++) {
            long partSize = downloadCheckPoint.downloadParts.get(i).end -
                    downloadCheckPoint.downloadParts.get(i).start + 1;
            contentLength += partSize;
            if (downloadCheckPoint.downloadParts.get(i).isCompleted) {
                completedLength += partSize;
            }
        }

        ProgressPublisher.publishResponseContentLength(listener, contentLength);
        ProgressPublisher.publishResponseBytesTransferred(listener, completedLength);
        downloadFileRequest.setProgressListener(null);

        // Concurrently download parts.
        for (int i = 0; i < downloadCheckPoint.downloadParts.size(); i++) {
            if (!downloadCheckPoint.downloadParts.get(i).isCompleted) {
                Task task = new Task(i, "download-" + i, downloadCheckPoint, i, downloadFileRequest, objectOperation,
                        listener);
                futures.add(service.submit(task));
                tasks.add(task);
            } else {
                taskResults.add(new PartResult(i + 1, downloadCheckPoint.downloadParts.get(i).start,
                        downloadCheckPoint.downloadParts.get(i).end, downloadCheckPoint.downloadParts.get(i).length,
                        downloadCheckPoint.downloadParts.get(i).crc));
            }
        }
        service.shutdown();

        // Waiting for all parts download,
        service.awaitTermination(Long.MAX_VALUE, TimeUnit.SECONDS);
        for (Future<PartResult> future : futures) {
            try {
                PartResult tr = future.get();
                taskResults.add(tr);
            } catch (ExecutionException e) {
                downloadFileRequest.setProgressListener(listener);
                throw e.getCause();
            }
        }

        // Sorts the download result by the part number.
        Collections.sort(taskResults, new Comparator<PartResult>() {
            @Override
            public int compare(PartResult p1, PartResult p2) {
                return p1.getNumber() - p2.getNumber();
            }
        });

        // sets the return value.
        downloadResult.setPartResults(taskResults);
        if (tasks.size() > 0) {
            downloadResult.setObjectMetadata(tasks.get(0).GetobjectMetadata());
        }
        downloadFileRequest.setProgressListener(listener);

        return downloadResult;
    }