Android Retrofit - onProgressUpdate for showing Progress Notification

Question

I'm currently using Retrofit by Square for Android network communications. Is there a way to get its progress during a task to create a progress notification, something similar to that which Facebook uses when uploading an image?

Use Case would be to load an image hopefully of full image quality without compression or scaling.

I see how it is possible with an asynctask but that would defeat the purpose of using Retrofit. However that might be the route I would have to take.

Answer 1

This answer is for Retrofit 1. For solution compatible with Retrofit 2 see this answer.

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I had the same problem and finally managed to do it. I was using spring lib before and what I show below kind worked for Spring but was inconsistent since I made a mistake on using it for the InputStream. I moved all my API's to use retrofit and upload was the last one on the list, I just override TypedFile writeTo() to update me on the bytes read to the OutputStream. Maybe this can be improved but as I said I made it when I was using Spring so I just reused it. This is the code for upload and it's working for me on my app, if you want download feedback then you can use @Streaming and read the inputStream.

ProgressListener

public interface ProgressListener {
 void transferred(long num);
}

CountingTypedFile

public class CountingTypedFile extends TypedFile {

 private static final int BUFFER_SIZE = 4096;

 private final ProgressListener listener;

 public CountingTypedFile(String mimeType, File file, ProgressListener listener) {
    super(mimeType, file);
    this.listener = listener;
 }

 @Override public void writeTo(OutputStream out) throws IOException {
    byte[] buffer = new byte[BUFFER_SIZE];
    FileInputStream in = new FileInputStream(super.file());
    long total = 0;
    try {
        int read;
        while ((read = in.read(buffer)) != -1) {
            total += read;
            this.listener.transferred(total);
            out.write(buffer, 0, read);
        }
    } finally {
        in.close();
    }
 }
}

MyApiService

public interface MyApiService {
 @Multipart
 @POST("/files")
 ApiResult uploadFile(@Part("file") TypedFile resource, @Query("path") String path);
}

SendFileTask

private class SendFileTask extends AsyncTask<String, Integer, ApiResult> {
    private ProgressListener listener;
    private String filePath;
    private FileType fileType;

    public SendFileTask(String filePath, FileType fileType) {
        this.filePath = filePath;
        this.fileType = fileType;
    }

    @Override
    protected ApiResult doInBackground(String... params) {
        File file = new File(filePath);
        totalSize = file.length();
        Logger.d("Upload FileSize[%d]", totalSize);
        listener = new ProgressListener() {
            @Override
            public void transferred(long num) {
                publishProgress((int) ((num / (float) totalSize) * 100));
            }
        };
        String _fileType = FileType.VIDEO.equals(fileType) ? "video/mp4" : (FileType.IMAGE.equals(fileType) ? "image/jpeg" : "*/*");
        return MyRestAdapter.getService().uploadFile(new CountingTypedFile(_fileType, file, listener), "/Mobile Uploads");
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        Logger.d(String.format("progress[%d]", values[0]));
        //do something with values[0], its the percentage so you can easily do
        //progressBar.setProgress(values[0]);
    }
}

The CountingTypedFile is just a copy of TypedFile but including the ProgressListener.