Java 8: How to chunk multipart file for POST request

Question

I have a multipart file, it will be an image or video, which needs to be chunked for POST request. How can I chunk the file into byte array segments?

edit: I'm using Twitter API to upload image, according to their docs, media must be chunked

Answer 1

I've found a solution thanks to https://www.baeldung.com/2013/04/04/multipart-upload-on-s3-with-jclouds/

public final class MediaUtil {

    public static int getMaximumNumberOfParts(byte[] byteArray) {
        int numberOfParts = byteArray.length / (1024 * 1024); // 1MB
        if (numberOfParts == 0) {
            return 1;
        }
        return numberOfParts;
    }

    public static List<byte[]> breakByteArrayIntoParts(byte[] byteArray, int maxNumberOfParts) {
        List<byte[]> parts = new ArrayList<>();
        int fullSize = byteArray.length;
        long dimensionOfPart = fullSize / maxNumberOfParts;
        for (int i = 0; i < maxNumberOfParts; i++) {
            int previousSplitPoint = (int) (dimensionOfPart * i);
            int splitPoint = (int) (dimensionOfPart * (i + 1));
            if (i == (maxNumberOfParts - 1)) {
                splitPoint = fullSize;
            }
            byte[] partBytes = Arrays.copyOfRange(byteArray, previousSplitPoint, splitPoint);
            parts.add(partBytes);
        }

        return parts;
    }
}

// Post the request
int maxParts = MediaUtil.getMaximumNumberOfParts(multipartFile.getBytes());

List<byte[]> bytes = MediaUtil.breakByteArrayIntoParts(multipartFile.getBytes(), maxParts);
int segment = 0;
for (byte[] b : bytes) {
    // POST request here
    segment++;
}