Example for uploading file using foreground service

FileUploadService.java

import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.support.v4.app.NotificationCompat;
import android.support.v4.app.NotificationManagerCompat;
import android.text.TextUtils;
import android.util.Log;

import java.util.ArrayList;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

public class FileUploadService extends Service {

    public static final String START_UPLOAD = "START_UPLOAD";
    public static final String CANCEL_UPLOAD = "CANCEL_UPLOAD";
    private static final String FILE_LIST = "FILE_LIST";
    private static final String TAG = FileUploadService.class.getSimpleName();
    private static final String CHANNEL_ID = "FILE_UPLOAD";
    private static final int NOTIFICATION_ID = 111;

    private BlockingQueue<String> fileQueue = new ArrayBlockingQueue<>(100);
    private Handler mFileUploadHandler = new Handler();
    private FileUploadTask mFileUploadTask;
    private boolean isFileUploadRunning;

    public static void startUpload(Context context, ArrayList<String> fileList) {
        Intent intent = new Intent(context, FileUploadService.class);
        intent.setAction(START_UPLOAD);
        intent.putStringArrayListExtra(FILE_LIST, fileList);
        context.startService(intent);
    }

    public static void cancelUpload(Context context) {
        Intent intent = new Intent(context, FileUploadService.class);
        intent.setAction(CANCEL_UPLOAD);
        context.startService(intent);
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        String action = intent.getAction();
        if (!TextUtils.isEmpty(action)) {
            switch (action) {
                case START_UPLOAD:
                    ArrayList<String> fileList = intent.getStringArrayListExtra(FILE_LIST);
                    if (fileList != null) {
                        startFileUpload(fileList);
                    }
                    break;
                case CANCEL_UPLOAD:
                    cancelFileUpload();
                    break;
            }
        }
        return super.onStartCommand(intent, flags, startId);
    }

    private void cancelFileUpload() {
        fileQueue.clear();
        if (mFileUploadTask != null) {
            mFileUploadHandler.removeCallbacks(mFileUploadTask);
            isFileUploadRunning = false;
            mFileUploadTask = null;
            hideNotification();
        }
    }

    private void startFileUpload(ArrayList<String> fileList) {
        for (String filePath : fileList) {
            if (!fileQueue.contains(filePath)) {
                fileQueue.add(filePath);
            }
        }
        startUploadingFile();
    }

    private void startUploadingFile() {
        if (mFileUploadTask == null) {
            mFileUploadTask = new FileUploadTask();
        }
        if (!isFileUploadRunning) {
            isFileUploadRunning = true;
            mFileUploadHandler.post(mFileUploadTask);
        }
    }

    class FileUploadTask implements Runnable {

        @Override
        public void run() {
            if (fileQueue.isEmpty()) {
                isFileUploadRunning = false;
                Log.e(TAG, "File Upload Complete.");
                hideNotification();
                return;
            }
            try {
                String filePath = fileQueue.take();
                Log.e(TAG, "Upload File: " + filePath);

                callUploadFileApi(filePath);

                showUploadNotification(filePath);
                Thread.sleep(2000);

                mFileUploadHandler.post(this);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    private void callUploadFileApi(String filePath) {

    }

    private void hideNotification() {
        NotificationManagerCompat.from(this).cancel(NOTIFICATION_ID);
        stopForeground(true);
    }

    private void showUploadNotification(String fileName) {
        String messageText = "";
        if (fileQueue.size() > 0) {
            messageText = messageText + "\n" + fileQueue.size() + " is remaining.";
        }
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, CHANNEL_ID);
        builder.setContentTitle("File Upload")
                .setContentText(messageText)
                //.setSmallIcon(R.drawable.ic_checkmark)
                .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher))
                .setAutoCancel(true);

        startForeground(NOTIFICATION_ID, builder.build());
    }

}