//inherit a class from com.github.snowdream.android.util.concurrent.AsyncTask
public class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
 public DownloadFilesTask(TaskListener<Integer, Long> listener) {
      //explicit inherit the construction from the super class.
      super(listener);
 }

/**
 * TODO 
 * if error occurs,carry it out.
 * 
 * if (listener != null) {
 *    listener.onError(new Throwable());
 * }
 */
protected Long doInBackground(URL... urls) {
     int count = urls.length;
     long totalSize = 0;
     for (int i = 0; i < count; i++) {
         totalSize += 10;
         publishProgress((int) ((i / (float) count) * 100));
         // Escape early if cancel() is called
         if (isCancelled()) break;
         try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
     }
     return totalSize;
 }
}

private TaskListener<Integer, Long> listener = new TaskListener<Integer, Long>(){

    @Override
    public void onStart() {
        super.onStart();
        Log.i("onStart()");
    }

    @Override
    public void onProgressUpdate(Integer... values) {
        super.onProgressUpdate(values);
        Log.i("onProgressUpdate(values)" + values[0] );
    }

    @Override
    public void onSuccess(Long result) {
        super.onSuccess(result);
        Log.i("onSuccess(result)" + result);
    }

    @Override
    public void onCancelled() {
        super.onCancelled();
        Log.i("onCancelled()");
    }

    @Override
    public void onError(Throwable thr) {
        super.onError(thr);
        Log.i("onError()");
    }

    @Override
    public void onFinish() {
        super.onFinish();
        Log.i("onFinish()");
    }

};

URL url = null;
try {
    url = new URL("http://www.baidu.com/");
} catch (MalformedURLException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

new DownloadFilesTask(listener).execute(url,url,url);