Class used to monitoring the file upload progress in Retrofit2 library.

ProgressRequestBody.java

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import okhttp3.MediaType;
import okhttp3.RequestBody;
import okio.BufferedSink;

/**
 * Class used to monitoring the file upload progress in Retrofit2 library.
 * <p/>
 * Created by douglas on 18/02/16.
 */
public class ProgressRequestBody extends RequestBody {
    private final byte[] mBytes;
    private final File mFile;
    private UploadCallbacks mListener;
    private final long mLenght;
    private final MediaType mMediaType;

    private static final int DEFAULT_BUFFER_SIZE = 1024;

    public interface UploadCallbacks {
        void onProgressUpdate(long uploaded, long lenght, int percentage);
    }

    private ProgressRequestBody(final byte[] bytes, final File file, long lenght, MediaType mediaType, UploadCallbacks listener) {
        mBytes = bytes;
        mFile = file;
        mLenght = lenght;
        mMediaType = mediaType;
        mListener = listener;
    }

    /**
     * Send byte array.
     *
     * @param bytes
     * @param mediaType
     * @param listener
     */
    public ProgressRequestBody(final byte[] bytes, final MediaType mediaType, final UploadCallbacks listener) {
        this(bytes, null, bytes.length, mediaType, listener);
    }

    /**
     * Send file.
     *
     * @param file
     * @param mediaType
     * @param listener
     * @throws FileNotFoundException
     */
    public ProgressRequestBody(final File file, final MediaType mediaType, final UploadCallbacks listener) throws FileNotFoundException {
        this(null, file, file.length(), mediaType, listener);
    }

    @Override
    public MediaType contentType() {
        return mMediaType;
    }

    @Override
    public long contentLength() throws IOException {
        return mLenght;
    }

    @Override
    public synchronized void writeTo(BufferedSink sink) throws IOException {
        InputStream is = createInputStream();
        try {
            byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
            long uploaded = 0;
            int read;

            while ((read = is.read(buffer)) != -1) {
                sink.write(buffer, 0, read);

                uploaded += read;
                mListener.onProgressUpdate(uploaded, mLenght, (int) (100f * uploaded / mLenght));
            }
        } finally {
            closeInputStream(is);
        }
    }

    private void closeInputStream(InputStream is) {
        try {
            is.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    private InputStream createInputStream() throws FileNotFoundException {
        if (mBytes != null) {
            return new ByteArrayInputStream(mBytes);
        } else if (mFile != null) {
            return new FileInputStream(mFile);
        }
        throw new IllegalArgumentException("File and bytes are null");
    }
}