Example of implementation of APK Expansion Files download process with a PhoneGap application

Sample.java

package com.phonegap.Sample;

import java.io.File;

import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.app.PendingIntent;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Bundle;
import android.os.Environment;
import android.os.Messenger;
import android.os.StatFs;
import android.util.Log;

import org.apache.cordova.*;

import com.google.android.vending.expansion.downloader.DownloadProgressInfo;
import com.google.android.vending.expansion.downloader.DownloaderClientMarshaller;
import com.google.android.vending.expansion.downloader.DownloaderServiceMarshaller;
import com.google.android.vending.expansion.downloader.Helpers;
import com.google.android.vending.expansion.downloader.IDownloaderClient;
import com.google.android.vending.expansion.downloader.IDownloaderService;
import com.google.android.vending.expansion.downloader.IStub;

public class Sample extends DroidGap implements IDownloaderClient
{
	private IStub mDownloaderClientStub;
	
	private IDownloaderService mRemoteService;
	
	private ProgressDialog mProgressDialog;

	private static final String LOG_TAG = "Sample";
	
	// The shared path to all app expansion files
	private final static String EXP_PATH = "/Android/obb/";
	
	/**
     * This is a little helper class that demonstrates simple testing of an
     * Expansion APK file delivered by Market. You may not wish to hard-code
     * things such as file lengths into your executable... and you may wish to
     * turn this code off during application development.
     */
	private static class XAPKFile {
		public final boolean mIsMain;
		public final int mFileVersion;
		public final long mFileSize;

		XAPKFile(boolean isMain, int fileVersion, long fileSize) {
			mIsMain = isMain;
			mFileVersion = fileVersion;
			mFileSize = fileSize;
		}
	}

	/**
	 * Here is where you place the data that the validator will use to determine
	 * if the file was delivered correctly. This is encoded in the source code
	 * so the application can easily determine whether the file has been
	 * properly delivered without having to talk to the server. If the
	 * application is using LVL for licensing, it may make sense to eliminate
	 * these checks and to just rely on the server.
	 */
	private static final XAPKFile[] xAPKS = {
		new XAPKFile(
			true, // true signifies a main file
			1, // the version of the APK that the file was uploaded against
			172667765L // the length of the file in bytes
		)
	};
	
	/**
     * Go through each of the APK Expansion files defined in the structure above
     * and determine if the files are present and match the required size. Free
     * applications should definitely consider doing this, as this allows the
     * application to be launched for the first time without having a network
     * connection present. Paid applications that use LVL should probably do at
     * least one LVL check that requires the network to be present, so this is
     * not as necessary.
     * 
     * @return true if they are present.
     */
	boolean expansionFilesDelivered() {
		for (XAPKFile xf : xAPKS) {
			String fileName = Helpers.getExpansionAPKFileName(this, xf.mIsMain, xf.mFileVersion);
			// Log.v(LOG_TAG, "XAPKFile name : " + fileName);
			if (!Helpers.doesFileExist(this, fileName, xf.mFileSize, false)) {
				Log.e(LOG_TAG, "ExpansionAPKFile doesn't exist or has a wrong size (" + fileName + ").");
				return false;
			}
		}
		return true;
	}
	
	@Override
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);

		// Check if expansion files are available before going any further
		if (!expansionFilesDelivered()) {

			try {
				Intent launchIntent = this.getIntent();

				// Build an Intent to start this activity from the Notification
				Intent notifierIntent = new Intent(Sample.this, Sample.this.getClass());
				notifierIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
				notifierIntent.setAction(launchIntent.getAction());

				if (launchIntent.getCategories() != null) {
					for (String category : launchIntent.getCategories()) {
						notifierIntent.addCategory(category);
					}
				}

				PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notifierIntent, PendingIntent.FLAG_UPDATE_CURRENT);

				// Start the download service (if required)
				Log.v(LOG_TAG, "Start the download service");
				int startResult = DownloaderClientMarshaller.startDownloadServiceIfRequired(this, pendingIntent, SampleDownloaderService.class);

				// If download has started, initialize activity to show progress
				if (startResult != DownloaderClientMarshaller.NO_DOWNLOAD_REQUIRED) {
					Log.v(LOG_TAG, "initialize activity to show progress");
					// Instantiate a member instance of IStub
					mDownloaderClientStub = DownloaderClientMarshaller.CreateStub(this, SampleDownloaderService.class);
					// Shows download progress
					mProgressDialog = new ProgressDialog(Sample.this);
					mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
					mProgressDialog.setMessage(getResources().getString(R.string.downloading_assets));
					mProgressDialog.setCancelable(false);
					mProgressDialog.show();
					return;
				}
				// If the download wasn't necessary, fall through to start the app
				else {
					Log.v(LOG_TAG, "No download required");
				}
			}
			catch (NameNotFoundException e) {
				Log.e(LOG_TAG, "Cannot find own package! MAYDAY!");
				e.printStackTrace();
			}
			catch (Exception e) {
				Log.e(LOG_TAG, e.getMessage());
				e.printStackTrace();
			}

		}

		// Set by <content src="index.html" /> in config.xml
		super.loadUrl(Config.getStartUrl());
		//super.loadUrl("file:///android_asset/www/index.html")
	}

	/**
	 * Connect the stub to our service on start.
	 */
	@Override
	protected void onStart() {
		if (null != mDownloaderClientStub) {
			mDownloaderClientStub.connect(this);
		}
		super.onStart();
	}

	/**
	 * Connect the stub from our service on resume
	 */
	@Override
	protected void onResume() {
		if (null != mDownloaderClientStub) {
			mDownloaderClientStub.connect(this);
		}
		super.onResume();
	}

	/**
	 * Disconnect the stub from our service on stop
	 */
	@Override
	protected void onStop() {
		if (null != mDownloaderClientStub) {
			mDownloaderClientStub.disconnect(this);
		}
		super.onStop();
	}

	@Override
	public void onServiceConnected(Messenger m) {
		mRemoteService = DownloaderServiceMarshaller.CreateProxy(m);
		mRemoteService.onClientUpdated(mDownloaderClientStub.getMessenger());
	}

	@Override
	public void onDownloadProgress(DownloadProgressInfo progress) {
		long percents = progress.mOverallProgress * 100 / progress.mOverallTotal;
		Log.v(LOG_TAG, "DownloadProgress:"+Long.toString(percents) + "%");
		mProgressDialog.setProgress((int) percents);
	}

	@Override
	public void onDownloadStateChanged(int newState) {
		Log.v(LOG_TAG, "DownloadStateChanged : " + getString(Helpers.getDownloaderStringResourceIDFromState(newState)));

		switch (newState) {
			case STATE_DOWNLOADING:
				Log.v(LOG_TAG, "Downloading...");
				break;
			case STATE_COMPLETED: // The download was finished
				// validateXAPKZipFiles();
				mProgressDialog.setMessage(getResources().getString(R.string.preparing_assets));
				// dismiss progress dialog
				mProgressDialog.dismiss();
				// Load url
				super.loadUrl(Config.getStartUrl());
				break;
			case STATE_FAILED_UNLICENSED:
			case STATE_FAILED_FETCHING_URL:
			case STATE_FAILED_SDCARD_FULL:
			case STATE_FAILED_CANCELED:
			case STATE_FAILED: 
				Builder alert = new AlertDialog.Builder(this);
				alert.setTitle(getResources().getString(R.string.error));
				alert.setMessage(getResources().getString(R.string.download_failed));
				alert.setNeutralButton(getResources().getString(R.string.close), null);
				alert.show();
				break;
		}
	}

}

XAPKAlarmReceiver.java

package com.phonegap.Sample;

import com.google.android.vending.expansion.downloader.DownloaderClientMarshaller;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager.NameNotFoundException;

/**
 * You should start your derived downloader class when this receiver gets the message 
 * from the alarm service using the provided service helper function within the
 * DownloaderClientMarshaller. This class must be then registered in your AndroidManifest.xml
 * file with a section like this:
 *         <receiver android:name=".XAPKAlarmReceiver"/>
 */
public class XAPKAlarmReceiver extends BroadcastReceiver {

	@Override
	public void onReceive(Context context, Intent intent) {
		try {
			DownloaderClientMarshaller.startDownloadServiceIfRequired(context, intent, XAPKDownloaderService.class);
		} catch (NameNotFoundException e) {S
			e.printStackTrace();
		}
	}

}

XAPKDownloaderService.java

package com.phonegap.Sample;

import com.google.android.vending.expansion.downloader.impl.DownloaderService;

/**
 * This class demonstrates the minimal client implementation of the
 * DownloaderService from the Downloader library.
 */
public class XAPKDownloaderService extends DownloaderService {

	// stuff for LVL -- MODIFY FOR YOUR APPLICATION!
	private static final String BASE64_PUBLIC_KEY = "YOUR_PUBLIC_KEY";

	// used by the preference obfuscater
	private static final byte[] SALT = new byte[] {
		1, 43, -12, -1, 54, 98, -100, -12, 43, 2, -8, -4, 9, 5, -106, -108, -33, 45, -1, 84
	};

	/**
	 * This public key comes from your Android Market publisher account, and it
	 * used by the LVL to validate responses from Market on your behalf.
	 */
	@Override
	public String getPublicKey() {
		return BASE64_PUBLIC_KEY;
	}

	/**
	 * This is used by the preference obfuscater to make sure that your
	 * obfuscated preferences are different than the ones used by other
	 * applications.
	 */
	@Override
	public byte[] getSALT() {
		return SALT;
	}

	/**
	 * Fill this in with the class name for your alarm receiver. We do this
	 * because receivers must be unique across all of Android (it's a good idea
	 * to make sure that your receiver is in your unique package)
	 */
	@Override
	public String getAlarmReceiverClassName() {
		return XAPKAlarmReceiver.class.getName();
	}

}

This is great, thanks!

Good one, thanks

Thanks!

Can you please tell me, how to reduce apk size as it is currently showing apk size+expansion file size on play store which is humongous..Is there any way to do this as in my case it is near about 300 mb??