AsynTask, VideoDownload and ProgressBar in Android

In this post I will be dealing about how to download a video in android.........

Downloading a video and simultaneously showing a progressbar in android is elegantly handled by AsyncTask class in Android. AsyncTask enables proper and easy use of the UI thread. This class allows to perform background operations and publish results on the UI thread without having to manipulate threads and/or handlers.

The code for video download is as follows.........as can be noted the Downloader class extends AsyncTask.

The Downloader Class has to be nested in your Activity.

public class DownloaderClass extends AsyncTask {

private boolean stop = false;
private FileOutputStream fileOutputStream;
private InputStream inputStream;
// this is the total size of the file
private int totalSize = 0;
// variable to store total downloaded bytes
private int downloadedSize = 0;

private HttpURLConnection urlConnection;
private File videoFile;

@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
showDialog(0);
}

@Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
// method

// String
// path=Environment.getExternalStorageDirectory().getAbsolutePath()+PATH+fileName;
try {
// set the download URL, a url that points to a file on the
// internet
// this is the file to be downloaded
System.out.println("doInBackground");

URL url = new URL(params[0]);

// create the new connection
urlConnection = (HttpURLConnection) url.openConnection();

// set up some things on the connection
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);

// and connect!
urlConnection.connect();

// set the path where we want to save the file
// in this case, going to save it on the root directory of the
// sd card.
// File SDCardRoot = Environment.getExternalStorageDirectory();
String videoPath = SDCARD_ROOT + params[1];
// create a new file, specifying the path, and the filename
// which we want to save the file as.

boolean exists = (new File(videoPath)).exists();
if (!exists) {
new File(videoPath).mkdirs();
}
videoFile = new File(videoPath, VIDEO_NAME);

// this will be used to write the downloaded data into the file
// we
// created
fileOutputStream = new FileOutputStream(videoFile);

// this will be used in reading the data from the internet
inputStream = urlConnection.getInputStream();

// this is the total size of the file
totalSize = urlConnection.getContentLength();

// create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0; // used to store a temporary size of the
// buffer

// now, read through the input buffer and write the contents to
// the
// file
while ((bufferLength = inputStream.read(buffer)) > 0 && !stop) {
// add the data in the buffer to the file in the file output
// stream (the file on the sd card
fileOutputStream.write(buffer, 0, bufferLength);
// add up the size so we know how much is downloaded
downloadedSize += bufferLength;
publishProgress((downloadedSize * 100) / totalSize);
// this is where you would do something to report the
// prgress,
// like this maybe
// System.out.println(downloadedSize + "/" + totalSize);

}
// close the output stream when done
fileOutputStream.close();

System.out.println("Downloading finished");

playVideo();
// catch some possible errors...
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}

@Override
protected void onProgressUpdate(Integer... values) {
// TODO Auto-generated method stub
Log.d("% Downloaded : ", "" + values[0]);
progressDialog.setProgress(values[0]);
}

@Override
protected void onCancelled() {
// TODO Auto-generated method stub

// finish();
System.out.println("onCancelled()");
stop = true;

urlConnection.disconnect();
if (fileOutputStream != null) {
try {
fileOutputStream.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

videoFile.delete();

}

@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
}}

In your activity call this Downloader class by calling execute() method and pass the videoUrl(from the video is be downloaded) and videoPath(where it is to be stored on SDCard)

as here........

downloaderClassObj.execute(VIDEO_URL, VIDEO_PATH);

That's it your video will start downloading and get stored on the specified location.............so simple isn't it :).

Now lets deal with the progressbar, for this you need to override onCreateDialog() method in your activity..........

@Override
protected Dialog onCreateDialog(int id) {
// TODO Auto-generated method stub

progressDialog = new ProgressDialog(this);
progressDialog.setCancelable(true);
progressDialog.setMessage("Downloading...");
// set the progress to be horizontal
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
// reset the bar to the default value of 0
progressDialog.setProgress(0);
progressDialog.setMax(100);
progressDialog.show();
progressDialog.setOnCancelListener(new OnCancelListener() {

public void onCancel(DialogInterface dialog) {
// TODO Auto-generated method stub
downloaderClassObj.cancel(true);
}
});

return progressDialog;
}

From your onPreExecute() method in Downloader class call showDialog() to initiate the progressbar.........the onPreExecute() method gets automatically called as soon as execute() method is called..............

And in the onProgressUpdate() you get the percentage download done...........

onProgressUpdate() gets called, with the function call publishProgress() in the loop while downloading the video............

That's it, your Video Downloading with a progress Bar is accomplished...........