VanGogh Image Loading Library (Re-creating Picasso)

MyVanGoghActivity.java

public class MyVanGoghActivity extends AppCompatActivity {

    ImageView imageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_crappy_picasso);
        // Downloading image and displaying it
        // Passing into imageview
        // Write it to disk
        // Passing into imagebutton
        // Setting it as the bg of a view
        imageView = (ImageView) findViewById(R.id.imageView);
        String url = "https://i.imgur.com/tGbaZCY.jpg";
        VanGogh.load(url, new OnImageListener() {
            public void onImageLoaded(Bitmap b) {
                imageView.setImageBitmap(b);
            }
        }
        
    }
}

VanGogh.java

public class VanGogh {

    // TODO Things to add if we had more time
    // Check for the network connectivity
    // Resize the bitmap efficiently loading
    // Caching (Memory, File cache)
    // -- Memory (Bitmap store to "image_cache/<url>"
    // -- Disk (Bitmap store to file "image_cache/<url>")
    // Placeholder
    // Fitting based on dimensions
    // Scaling image
    // Check if the url is valid
    // Handle exceptions during download
    // Add logging mechanisms

    public interface OnImageListener {
        public void onImageLoaded(Bitmap b, int res);
    }

    public static void load(String urlStr, OnImageListener listener) {
      // Start the background task
        new DownloadImageTask(urlStr, listener).execute();
    }
    
    // Convenience method for loading into an imageView
    public static void load(String urlStr, final ImageView imageView) {
        load(urlStr, new OnImageListener() {
            @Override
            public void onImageLoaded(Bitmap b, int res) {
                imageView.setImageBitmap(b);
            }
        });
    }

    // Background Thread
    // 1. From the UIThread,
    // we need start a task
    //   1b. Pass data to
    // bg thread (url)
    // 2. Run some task in bg
    // 3. Pass the data back
    //  to the UIThread
    public static class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
        String url;
        OnImageListener listener;

        public DownloadImageTask(String url, OnImageListener listener) {
            this.url = url;
            this.listener = listener;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected Bitmap doInBackground(String... params) {
            // 1. Create an asynchronous thread
            // 2. Check for networking
            // 3. Create a connection
            URL urlO = null;
            InputStream stream = null;
            try {
                urlO = new URL(url);
                HttpURLConnection conn = (HttpURLConnection)
                        urlO.openConnection();
                // 4. Open the input stream
                conn.connect();
                stream = conn.getInputStream();
                // 5. Download and Decode data
                Bitmap bitmap = BitmapFactory.decodeStream(stream);
                // 6. Close the stream
                stream.close();
                /// Return Bitmap
                return bitmap;
            } catch (IOException e) {
                e.printStackTrace();
                // Smart exception loggin
            }
            return null;
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            // 7. Call the listener
            if (listener != null) {
                listener.onImageLoaded(bitmap, 200);
            }
        }
    }


}