Android Open Source - android-002 Downloader Task

• Back to App/course  ↑

From Project

Back to project page android-002.

License

The source code is released under:

Apache License

Java Source Code

package course.labs.notificationslab;
/*w ww  .  ja  v  a  2 s  .c  om*/
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.RemoteViews;

public class DownloaderTask extends AsyncTask<String, Void, String[]> {

  private static final int SIM_NETWORK_DELAY = 1000;
  private static final String TAG = "Lab-Notifications";
  private final int MY_NOTIFICATION_ID = 11151990;
  private String mFeeds[] = new String[3];
  private MainActivity mParentActivity;
  private Context mApplicationContext;

  // Raw feed file IDs used in this offline version of the app
  public static final int txtFeeds[] = { R.raw.tswift, R.raw.rblack,
      R.raw.lgaga };

  // Constructor
  public DownloaderTask(MainActivity parentActivity) {
    super();

    mParentActivity = parentActivity;
    mApplicationContext = parentActivity.getApplicationContext();

  }

  @Override
  protected String[] doInBackground(String... urlParameters) {
    Log.i(TAG, "Entered doInBackground()");

    return download(urlParameters);

  }

  // Simulate downloading tweets from the network
  private String[] download(String urlParameters[]) {

    boolean downloadCompleted = false;

    try {

      for (int idx = 0; idx < urlParameters.length; idx++) {

        InputStream inputStream;
        BufferedReader in;

        try {
          // Pretend the tweets take a long time to load
          Thread.sleep(SIM_NETWORK_DELAY);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }

        inputStream = mApplicationContext.getResources()
            .openRawResource(txtFeeds[idx]);
        in = new BufferedReader(new InputStreamReader(inputStream));

        String readLine;
        StringBuffer buf = new StringBuffer();

        while ((readLine = in.readLine()) != null) {
          buf.append(readLine);
        }

        mFeeds[idx] = buf.toString();

        if (null != in) {
          in.close();
        }
      }

      downloadCompleted = true;

    } catch (IOException e) {
      e.printStackTrace();
    }

    Log.i(TAG, "Tweet Download Completed:" + downloadCompleted);

    notify(downloadCompleted);

    return mFeeds;

  }

  // Call back to the MainActivity to update the feed display

  @Override
  protected void onPostExecute(String[] result) {
    super.onPostExecute(result);

    if (mParentActivity != null) {
      mParentActivity.setRefreshed(result);
    }

  }

  // If necessary, notifies the user that the tweet downloads are complete.
  // Sends an ordered broadcast back to the BroadcastReceiver in MainActivity
  // to determine whether the notification is necessary.

  private void notify(final boolean success) {
    Log.i(TAG, "Entered notify()");

    final Intent restartMainActivtyIntent = new Intent(mApplicationContext,
        MainActivity.class);
    restartMainActivtyIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

    if (success) {

      // Save tweets to a file
      saveTweetsToFile();

    }

    // Sends an ordered broadcast to determine whether MainActivity is
    // active and in the foreground. Creates a new BroadcastReceiver
    // to receive a result indicating the state of MainActivity

    // The Action for this broadcast Intent is
    // MainActivity.DATA_REFRESHED_ACTION
    // The result MainActivity.IS_ALIVE, indicates that MainActivity 
    // is active and in the foreground.

    mApplicationContext.sendOrderedBroadcast(new Intent(
        MainActivity.DATA_REFRESHED_ACTION), null,
        new BroadcastReceiver() {

          final String failMsg = "Download has failed. Please retry Later.";
          final String successMsg = "Download completed successfully.";

          @Override
          public void onReceive(Context context, Intent intent) {

            Log.i(TAG,
                "Entered result receiver's onReceive() method");

            // TODO: Check whether the result code is not MainActivity.IS_ALIVE

//            if (false || true) {
            if ( getResultCode() != MainActivity.IS_ALIVE) {
              Log.i(TAG, "MainActivity not alive - sending notification...");

              // TODO: If so, create a PendingIntent using the
              // restartMainActivityIntent and set its flags
              // to FLAG_UPDATE_CURRENT
              PendingIntent pendingIntent = 
                PendingIntent.getActivity(context, 
                            MY_NOTIFICATION_ID, 
                            restartMainActivtyIntent, 
                            PendingIntent.FLAG_UPDATE_CURRENT);

              // Uses R.layout.custom_notification for the
              // layout of the notification View. The xml
              // file is in res/layout/custom_notification.xml

              RemoteViews mContentView = new RemoteViews(
                  mApplicationContext.getPackageName(),
                  R.layout.custom_notification);

              // TODO: Set the notification View's text to
              // reflect whether the download completed
              // successfully
              String msg = success ? successMsg : failMsg;
              mContentView.setTextViewText(R.id.text, msg);

              // TODO: Use the Notification.Builder class to
              // create the Notification. You will have to set
              // several pieces of information. You can use
              // android.R.drawable.stat_sys_warning
              // for the small icon. You should also
              // setAutoCancel(true).
              Notification notification 
                = new Notification.Builder(mApplicationContext)
                       .setContentTitle("Tweet download finished")
                       .setContentText(msg)
                       .setSmallIcon(android.R.drawable.stat_sys_warning)
                       .setAutoCancel(true)
                       .setContentIntent(pendingIntent)
                       .build();
              
              
              // TODO: Send the notification
              NotificationManager notificationManager =
                (NotificationManager) mApplicationContext.getSystemService(
                        Context.NOTIFICATION_SERVICE);
              notificationManager.notify(MY_NOTIFICATION_ID, notification);

              Log.i(TAG, "Notification Area Notification sent");
            } else {
              Log.i(TAG, "MainActivity is alive - no need to notify...");
            }
          }
        }, null, 0, null, null);
  }

  // Saves the tweets to a file
  private void saveTweetsToFile() {
    PrintWriter writer = null;
    try {
      FileOutputStream fos = mApplicationContext.openFileOutput(
          MainActivity.TWEET_FILENAME, Context.MODE_PRIVATE);
      writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
          fos)));

      for (String s : mFeeds) {
        writer.println(s);
      }
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      if (null != writer) {
        writer.close();
      }
    }
  }

}

Java Source Code List

• Back to App/course  ↑