Downloading Image Via AsyncTask and displaying it in an Imageview without storing in sdcard

Issue

I want to download an image via AsyncTask and want to display it in an ImageView I am able to do it normally but I also want to show the progress to the user and do all this without having to store the file in the SDcard.

Here is what I have done so far.

class DownloadFileFromURL extends AsyncTask<String, String, String> {

/**
 * Before starting background thread
 * Show Progress Bar Dialog
 * */
@Override
protected void onPreExecute() {
    super.onPreExecute();
    showDialog(progress_bar_type);
}

/**
 * Downloading file in background thread
 * */
@Override
protected String doInBackground(String... f_url) {
    int count;
    try {
        URL url = new URL(f_url[0]);
        URLConnection conection = url.openConnection();
        conection.connect();
        // getting file length
        int lenghtOfFile = conection.getContentLength();

        // input stream to read file - with 8k buffer
        InputStream input = new BufferedInputStream(url.openStream(), 8192);

        // Output stream to write file
        OutputStream output = new FileOutputStream("/sdcard/downloadedfile.jpg");

        byte data[] = new byte[1024];

        long total = 0;

        while ((count = input.read(data)) != -1) {
            total += count;
            // publishing the progress....
            // After this onProgressUpdate will be called
            publishProgress(""+(int)((total*100)/lenghtOfFile));

            // writing data to file
            output.write(data, 0, count);
        }

        // flushing output
        output.flush();

        // closing streams
        output.close();
        input.close();

    } catch (Exception e) {
        Log.e("Error: ", e.getMessage());
    }

    return null;
}

/**
 * Updating progress bar
 * */
protected void onProgressUpdate(String... progress) {
    // setting progress percentage
    pDialog.setProgress(Integer.parseInt(progress[0]));
}

/**
 * After completing background task
 * Dismiss the progress dialog
 * **/
@Override
protected void onPostExecute(String file_url) {
    // dismiss the dialog after the file was downloaded
    dismissDialog(progress_bar_type);

    // Displaying downloaded image into image view
    // Reading image path from sdcard
    String imagePath = Environment.getExternalStorageDirectory().toString() + "/downloadedfile.jpg";
    // setting downloaded into image view
    my_image.setImageDrawable(Drawable.createFromPath(imagePath));
}

}

Solution

If you don't want to download image locally, you should use ByteArrayOutputStream instead of FileOutputStream.

And this is the key code:

ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
    total += count;
    publishProgress(""+(int)((total*100)/lenghtOfFile));

    outputStream.write(data, 0, count);
}

//after downloading the image
byte[] imageData = outputStream.toByteArray();
Bitmap bitmap = BitmapFactory.decodeByteArray(imageData, 0, imageData.length);
my_image.setImageBitmap(bitmap);

I didn't test it, but I believe this can help you.

Answered By - L. Swifter