Android Open Source - MobileCodeGenerator Image Downloading Task

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License

The source code is released under:

GNU General Public License

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Java Source Code

package it.polimi.valtellina;
/*from   w w  w .java2 s.  c  o  m*/
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.widget.ImageView;

public class ImageDownloadingTask extends AsyncTask<ImageView, Void, Bitmap> {
  private ImageView imageView;
  private String imageUri;

  /**
   * This task attempts to download an image from the Network:
   * in case of success, it sets the proper ImageView,
   * in case of failure, it does nothing (ImageView remains without image).
   */
  public ImageDownloadingTask() {
  };

  /***
   * Attempts to download the image from the Network.
   * @params params[0] = ImageView where to put the image to be downloaded. The url must be attached in a tag on the ImageView.
   */
  @Override
  protected Bitmap doInBackground(ImageView... params) {
    imageView = (ImageView) params[0];
    Bitmap bitmap = null;
    if (imageView != null) {
      imageUri = imageView.getTag().toString();
      try {
        bitmap = downloadImage(imageUri);
      } catch (MalformedURLException e) {
        e.printStackTrace();
      } catch (IOException e) { //failure in downloading the image
        e.printStackTrace();
      }
    }
    return bitmap;
  }

  /**
   * Attempts to download the image at the url passed as parameter: it returns the bitmap in case of success, null otherwise.
   * @param imageUrl
   */
  protected Bitmap downloadImage(String imageUrl)
      throws MalformedURLException, IOException {
    HttpURLConnection connection = (HttpURLConnection) new URL(imageUrl)
        .openConnection();
    connection.connect();
    Bitmap downloadedBitmap = BitmapFactory.decodeStream(connection
        .getInputStream()); //Convert to bitmap
    connection.disconnect();
    return downloadedBitmap;
  }

  /***
   * If the image has been downloaded properly it sets the ImageView.
   */
  @Override
  protected void onPostExecute(Bitmap bitmap) {
    super.onPostExecute(bitmap);
    if (bitmap != null) {
      String imageUri = imageView.getTag().toString();
      if (this.imageUri.equals(imageUri)) { //needed for synchronization reasons
        this.imageView.setImageBitmap(bitmap);
      }
    }
  }
}

Java Source Code List