Download image with OKHttpClient in AsyncTask.

DownloadImageTask.java

package io.triptime.android.service;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.util.Log;

import java.io.IOException;

import io.triptime.android.TripTime;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

/**
 * Created by edward_chiang on 27/06/2017.
 */

public class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {

    private OnBitmapDownloadListener onBitmapDownloadListener;

    @Override
    protected Bitmap doInBackground(String... strings) {
        final OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
                .url(strings[0])
                .build();

        Response response = null;
        Bitmap mIcon11 = null;
        try {
            response = client.newCall(request).execute();
        } catch (IOException e) {
            e.printStackTrace();
        }
        if (response.isSuccessful()) {
            try {
                mIcon11 = BitmapFactory.decodeStream(response.body().byteStream());
            } catch (Exception e) {
                Log.e(TripTime.TAG, e.getMessage());
                e.printStackTrace();
            }

        }
        return mIcon11;
    }

    @Override
    protected void onPostExecute(Bitmap bitmap) {
        super.onPostExecute(bitmap);
        if (onBitmapDownloadListener != null) {
            onBitmapDownloadListener.result(bitmap);
        }
    }

    public OnBitmapDownloadListener getOnBitmapDownloadListener() {
        return onBitmapDownloadListener;
    }

    public void setOnBitmapDownloadListener(OnBitmapDownloadListener onBitmapDownloadListener) {
        this.onBitmapDownloadListener = onBitmapDownloadListener;
    }

    public interface OnBitmapDownloadListener {
        public void result(Bitmap bitmap);
    }
}