ABP/Android core

src/org/adblockplus/android/AdblockPlus.java

+package org.adblockplus.android;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.ArrayList;
+import java.util.Calendar;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.TimeZone;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.FutureTask;
+
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.parsers.SAXParser;
+import javax.xml.parsers.SAXParserFactory;
+
+import org.adblockplus.android.updater.AlarmReceiver;
+import org.apache.commons.lang.StringEscapeUtils;
+import org.apache.commons.lang.StringUtils;
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.xml.sax.SAXException;
+
+import android.app.AlarmManager;
+import android.app.Application;
+import android.app.PendingIntent;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.content.res.AssetManager;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
+import android.os.AsyncTask;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.Handler;
+import android.os.Message;
+import android.os.SystemClock;
+import android.preference.PreferenceManager;
+import android.util.Log;
+import android.widget.Toast;
+
+public class AdblockPlus extends Application
+{
+  private final static String TAG = "Application";
+
+  private final static int MSG_TOAST = 1;
+
+  /**
+   * Broadcasted when subscription status changes.
+   */
+  public final static String BROADCAST_SUBSCRIPTION_STATUS = "org.adblockplus.android.subscription.status";
+  /**
+   * Broadcasted when filter match check is performed.
+   */
+  public final static String BROADCAST_FILTER_MATCHES = "org.adblockplus.android.filter.matches";
+
+  private List<Subscription> subscriptions;
+
+  private JSThread js;
+
+  /**
+   * Indicates interactive mode (used to listen for subscription status
+   * changes).
+   */
+  private boolean interactive = false;
+
+  private boolean generateCrashReport = false;
+
+  private static AdblockPlus instance;
+
+  /**
+   * Returns pointer to itself (singleton pattern).
+   */
+  public static AdblockPlus getApplication()
+  {
+    return instance;
+  }
+
+  public int getBuildNumber()
+  {
+    int buildNumber = -1;
+    try
+    {
+      PackageInfo pi = getPackageManager().getPackageInfo(getPackageName(), 0);
+      buildNumber = pi.versionCode;
+    }
+    catch (NameNotFoundException e)
+    {
+      // ignore - this shouldn't happen
+      Log.e(TAG, e.getMessage(), e);
+    }
+    return buildNumber;
+  }
+
+  /**
+   * Returns device name in user-friendly format
+   */
+  public static String getDeviceName()
+  {
+    String manufacturer = Build.MANUFACTURER;
+    String model = Build.MODEL;
+    if (model.startsWith(manufacturer))
+      return capitalize(model);
+    else
+      return capitalize(manufacturer) + " " + model;
+  }
+
+  private static String capitalize(String s)
+  {
+    if (s == null || s.length() == 0)
+      return "";
+    char first = s.charAt(0);
+    if (Character.isUpperCase(first))
+      return s;
+    else
+      return Character.toUpperCase(first) + s.substring(1);
+  }
+
+  /**
+   * Checks if device has a WiFi connection available.
+   */
+  public static boolean isWiFiConnected(Context context)
+  {
+    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+    NetworkInfo networkInfo = null;
+    if (connectivityManager != null)
+    {
+      networkInfo = connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
+    }
+    return networkInfo == null ? false : networkInfo.isConnected();
+  }
+
+  /**
+   * Checks if application can write to external storage.
+   */
+  public boolean checkWriteExternalPermission()
+  {
+
+    String permission = "android.permission.WRITE_EXTERNAL_STORAGE";
+    int res = checkCallingOrSelfPermission(permission);
+    return res == PackageManager.PERMISSION_GRANTED;
+  }
+
+  /**
+   * Returns list of known subscriptions.
+   */
+  public List<Subscription> getSubscriptions()
+  {
+    if (subscriptions == null)
+    {
+      subscriptions = new ArrayList<Subscription>();
+
+      SAXParserFactory factory = SAXParserFactory.newInstance();
+      SAXParser parser;
+      try
+      {
+        parser = factory.newSAXParser();
+        parser.parse(getAssets().open("subscriptions.xml"), new SubscriptionParser(subscriptions));
+      }
+      catch (ParserConfigurationException e)
+      {
+        // TODO Auto-generated catch block
+        Log.e(TAG, e.getMessage(), e);
+      }
+      catch (SAXException e)
+      {
+        // TODO Auto-generated catch block
+        Log.e(TAG, e.getMessage(), e);
+      }
+      catch (IOException e)
+      {
+        // TODO Auto-generated catch block
+        Log.e(TAG, e.getMessage(), e);
+      }
+    }
+    return subscriptions;
+  }
+
+  /**
+   * Returns subscription information.
+   * 
+   * @param url
+   *          subscription url
+   */
+  public Subscription getSubscription(String url)
+  {
+    List<Subscription> subscriptions = getSubscriptions();
+
+    for (Subscription subscription : subscriptions)
+    {
+      if (subscription.url.equals(url))
+        return subscription;
+    }
+    return null;
+  }
+
+  /**
+   * Adds provided subscription and removes previous subscriptions if any.
+   * 
+   * @param subscription
+   *          Subscription to add
+   */
+  public void setSubscription(Subscription subscription)
+  {
+    if (subscription != null)
+    {
+      final JSONObject jsonSub = new JSONObject();
+      try
+      {
+        jsonSub.put("url", subscription.url);
+        jsonSub.put("title", subscription.title);
+        jsonSub.put("homepage", subscription.homepage);
+        js.execute(new Runnable()
+        {
+          @Override
+          public void run()
+          {
+            js.evaluate("clearSubscriptions()");
+            js.evaluate("addSubscription(\"" + StringEscapeUtils.escapeJavaScript(jsonSub.toString()) + "\")");
+          }
+        });
+      }
+      catch (JSONException e)
+      {
+        // TODO Auto-generated catch block
+        Log.e(TAG, e.getMessage(), e);
+      }
+    }
+  }
+
+  /**
+   * Forces subscriptions refresh.
+   */
+  public void refreshSubscription()
+  {
+    js.execute(new Runnable()
+    {
+      @Override
+      public void run()
+      {
+        js.evaluate("refreshSubscriptions()");
+      }
+    });
+  }
+
+  /**
+   * Selects which subscription to offer for the first time.
+   * 
+   * @return offered subscription
+   */
+  public Subscription offerSubscription()
+  {
+    Subscription selectedItem = null;
+    String selectedPrefix = null;
+    int matchCount = 0;
+    for (Subscription subscription : getSubscriptions())
+    {
+      if (selectedItem == null)
+        selectedItem = subscription;
+
+      String prefix = checkLocalePrefixMatch(subscription.prefixes);
+      if (prefix != null)
+      {
+        if (selectedPrefix == null || selectedPrefix.length() < prefix.length())
+        {
+          selectedItem = subscription;
+          selectedPrefix = prefix;
+          matchCount = 1;
+        }
+        else if (selectedPrefix != null && selectedPrefix.length() == prefix.length())
+        {
+          matchCount++;
+
+          // If multiple items have a matching prefix of the
+          // same length select one of the items randomly,
+          // probability should be the same for all items.
+          // So we replace the previous match here with
+          // probability 1/N (N being the number of matches).
+          if (Math.random() * matchCount < 1)
+          {
+            selectedItem = subscription;
+            selectedPrefix = prefix;
+          }
+        }
+      }
+    }
+    return selectedItem;
+  }
+
+  /**
+   * Verifies that subscriptions are loaded and returns flag of subscription
+   * presence.
+   * 
+   * @return true if at least one subscription is present and downloaded
+   */
+  public boolean verifySubscriptions()
+  {
+    Future<Boolean> future = js.submit(new Callable<Boolean>()
+    {
+      @Override
+      public Boolean call() throws Exception
+      {
+        Boolean result = (Boolean) js.evaluate("verifySubscriptions()");
+        return result;
+      }
+    });
+    try
+    {
+      return future.get().booleanValue();
+    }
+    catch (InterruptedException e)
+    {
+      // TODO Auto-generated catch block
+      Log.e(TAG, e.getMessage(), e);
+    }
+    catch (ExecutionException e)
+    {
+      // TODO Auto-generated catch block
+      Log.e(TAG, e.getMessage(), e);
+    }
+    return false;
+  }
+
+  /**
+   * Returns ElemHide selectors for domain.
+   * 
+   * @return ready to use HTML element with CSS selectors
+   */
+  public String getSelectorsForDomain(final String domain)
+  {
+    Future<String> future = js.submit(new Callable<String>()
+    {
+      @Override
+      public String call() throws Exception
+      {
+        String result = (String) js.evaluate("ElemHide.getSelectorsForDomain('" + domain + "')");
+        return result;
+      }
+    });
+    try
+    {
+      return future.get();
+    }
+    catch (InterruptedException e)
+    {
+      // TODO Auto-generated catch block
+      Log.e(TAG, e.getMessage(), e);
+    }
+    catch (ExecutionException e)
+    {
+      // TODO Auto-generated catch block
+      Log.e(TAG, e.getMessage(), e);
+    }
+    return null;
+  }
+
+  private class MatchesCallable implements Callable<Boolean>
+  {
+    private String url;
+    private String query;
+    private String reqHost;
+    private String refHost;
+    private String accept;
+
+    MatchesCallable(String url, String query, String reqHost, String refHost, String accept)
+    {
+      this.url = url;
+      this.query = query;
+      this.reqHost = reqHost != null ? reqHost : "";
+      this.refHost = refHost != null ? refHost : "";
+      this.accept = accept != null ? accept : "";
+    }
+
+    @Override
+    public Boolean call() throws Exception
+    {
+      Boolean result = (Boolean) js.evaluate("matchesAny('" + url + "', '" + query + "', '" + reqHost + "', '" + refHost + "', '" + accept + "');");
+      return result;
+    }
+  }
+
+  /**
+   * Checks if filters match request parameters.
+   * 
+   * @param url
+   *          Request URL
+   * @param query
+   *          Request query string
+   * @param reqHost
+   *          Request host
+   * @param refHost
+   *          Request referrer header
+   * @param accept
+   *          Request accept header
+   * @return true if matched filter was found
+   * @throws Exception
+   */
+  public boolean matches(String url, String query, String reqHost, String refHost, String accept) throws Exception
+  {
+    Callable<Boolean> callable = new MatchesCallable(url, query, reqHost, refHost, accept);
+    Future<Boolean> future = js.submit(callable);
+    boolean matches = future.get().booleanValue();
+    sendBroadcast(new Intent(BROADCAST_FILTER_MATCHES).putExtra("url", url).putExtra("matches", matches));
+    return matches;
+  }
+
+  /**
+   * Notifies JS code that application entered interactive mode.
+   */
+  public void startInteractive()
+  {
+    js.execute(new Runnable()
+    {
+      @Override
+      public void run()
+      {
+        js.evaluate("startInteractive()");
+      }
+    });
+    interactive = true;
+  }
+
+  /**
+   * Notifies JS code that application quit interactive mode.
+   */
+  public void stopInteractive()
+  {
+    js.execute(new Runnable()
+    {
+      @Override
+      public void run()
+      {
+        js.evaluate("stopInteractive()");
+      }
+    });
+    interactive = false;
+  }
+
+  /**
+   * Returns prefixes that match current user locale.
+   */
+  public String checkLocalePrefixMatch(String[] prefixes)
+  {
+    if (prefixes == null || prefixes.length == 0)
+      return null;
+
+    String locale = Locale.getDefault().toString().toLowerCase();
+
+    for (int i = 0; i < prefixes.length; i++)
+      if (locale.startsWith(prefixes[i].toLowerCase()))
+        return prefixes[i];
+
+    return null;
+  }
+
+  /**
+   * Starts JS engine. It also initiates subscription refresh if it is enabled
+   * in user settings.
+   */
+  public void startEngine()
+  {
+    if (js == null)
+    {
+      Log.i(TAG, "startEngine");
+      js = new JSThread(this);
+      js.start();
+
+      final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
+      final int refresh = Integer.valueOf(prefs.getString(getString(R.string.pref_refresh), Integer.toString(getResources().getInteger(R.integer.def_refresh))));
+      final boolean wifionly = prefs.getBoolean(getString(R.string.pref_wifirefresh), getResources().getBoolean(R.bool.def_wifirefresh));
+      // Refresh if user selected refresh on each start
+      if (refresh == 1 && (!wifionly || isWiFiConnected(this)))
+      {
+        refreshSubscription();
+      }
+    }
+  }
+
+  /**
+   * Stops JS engine.
+   * 
+   * @param implicitly
+   *          stop even in interactive mode
+   */
+  public void stopEngine(boolean implicitly)
+  {
+    if ((implicitly || !interactive) && js != null)
+    {
+      js.stopEngine();
+      try
+      {
+        js.join();
+      }
+      catch (InterruptedException e)
+      {
+        Log.e(TAG, e.getMessage(), e);
+      }
+      js = null;
+    }
+  }
+
+  /**
+   * Sets or removes crash handler according to user setting
+   */
+  public void updateCrashReportStatus()
+  {
+    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
+    boolean report = prefs.getBoolean(getString(R.string.pref_crashreport), getResources().getBoolean(R.bool.def_crashreport));
+    if (report != generateCrashReport)
+    {
+      if (report)
+      {
+        Thread.setDefaultUncaughtExceptionHandler(new CrashHandler(this));
+      }
+      else
+      {
+        try
+        {
+          CrashHandler handler = (CrashHandler) Thread.getDefaultUncaughtExceptionHandler();
+          Thread.setDefaultUncaughtExceptionHandler(handler.getDefault());
+        }
+        catch (ClassCastException e)
+        {
+          // ignore - already default handler
+        }
+      }
+      generateCrashReport = report;
+    }
+  }
+
+  /**
+   * Sets Alarm to call updater after specified number of minutes or after one
+   * day if
+   * minutes are set to 0.
+   * 
+   * @param minutes
+   *          number of minutes to wait
+   */
+  public void scheduleUpdater(int minutes)
+  {
+    Calendar updateTime = Calendar.getInstance();
+
+    if (minutes == 0)
+    {
+      // Start update checks at 10:00 GMT...
+      updateTime.setTimeZone(TimeZone.getTimeZone("GMT"));
+      updateTime.set(Calendar.HOUR_OF_DAY, 10);
+      updateTime.set(Calendar.MINUTE, 0);
+      // ...next day
+      updateTime.add(Calendar.HOUR_OF_DAY, 24);
+      // Spread out the “mass downloading” for 6 hours
+      updateTime.add(Calendar.MINUTE, (int) Math.random() * 60 * 6);
+    }
+    else
+    {
+      updateTime.add(Calendar.MINUTE, minutes);
+    }
+
+    Intent updater = new Intent(this, AlarmReceiver.class);
+    PendingIntent recurringUpdate = PendingIntent.getBroadcast(this, 0, updater, PendingIntent.FLAG_CANCEL_CURRENT);
+    // Set non-waking alarm
+    AlarmManager alarms = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
+    alarms.set(AlarmManager.RTC, updateTime.getTimeInMillis(), recurringUpdate);
+  }
+
+  @Override
+  public void onCreate()
+  {
+    super.onCreate();
+    instance = this;
+
+    // Check for crash report
+    try
+    {
+      InputStreamReader reportFile = new InputStreamReader(openFileInput(CrashHandler.REPORT_FILE));
+      final char[] buffer = new char[0x1000];
+      StringBuilder out = new StringBuilder();
+      int read;
+      do
+      {
+        read = reportFile.read(buffer, 0, buffer.length);
+        if (read > 0)
+          out.append(buffer, 0, read);
+      }
+      while (read >= 0);
+      String report = out.toString();
+      if (!"".equals(report))
+      {
+        final Intent intent = new Intent(this, CrashReportDialog.class);
+        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+        intent.putExtra("report", report);
+        startActivity(intent);
+      }
+    }
+    catch (FileNotFoundException e)
+    {
+      // ignore
+    }
+    catch (IOException e)
+    {
+      // TODO Auto-generated catch block
+      Log.e(TAG, e.getMessage(), e);
+    }
+
+    if (!getResources().getBoolean(R.bool.def_release))
+    {
+      // Set crash handler
+      updateCrashReportStatus();
+      // Initiate update check
+      scheduleUpdater(0);
+    }
+  }
+
+  /**
+   * Handler for showing toast messages from JS code.
+   */
+  private static final Handler messageHandler = new Handler()
+  {
+    public void handleMessage(Message msg)
+    {
+      if (msg.what == MSG_TOAST)
+      {
+        Toast.makeText(AdblockPlus.getApplication(), msg.getData().getString("message"), Toast.LENGTH_LONG).show();
+      }
+    }
+  };
+
+  /**
+   * JS execution thread.
+   */
+  private final class JSThread extends Thread
+  {
+    private JSEngine jsEngine;
+    private volatile boolean run = true;
+    private Context context;
+    private final LinkedList<Runnable> queue = new LinkedList<Runnable>();
+    private long delay = -1;
+
+    JSThread(Context context)
+    {
+      this.context = context;
+    }
+
+    // JS helper
+    @SuppressWarnings("unused")
+    public String readJSFile(String name)
+    {
+      String result = "";
+      AssetManager assetManager = getAssets();
+      try
+      {
+        InputStreamReader reader = new InputStreamReader(assetManager.open("js" + File.separator + name));
+        final char[] buffer = new char[0x10000];
+        StringBuilder out = new StringBuilder();
+        int read;
+        do
+        {
+          read = reader.read(buffer, 0, buffer.length);
+          if (read > 0)
+            out.append(buffer, 0, read);
+        }
+        while (read >= 0);
+        result = out.toString();
+      }
+      catch (IOException e)
+      {
+        Log.e(TAG, e.getMessage(), e);
+      }
+      return result;
+    }
+
+    // JS helper
+    public FileInputStream getInputStream(String path)
+    {
+      Log.d(TAG, path);
+      File f = new File(path);
+      try
+      {
+        return openFileInput(f.getName());
+      }
+      catch (FileNotFoundException e)
+      {
+        Log.e(TAG, e.getMessage(), e);
+      }
+      return null;
+    }
+
+    // JS helper
+    public FileOutputStream getOutputStream(String path)
+    {
+      Log.d(TAG, path);
+      File f = new File(path);
+      try
+      {
+        return openFileOutput(f.getName(), MODE_PRIVATE);
+      }
+      catch (FileNotFoundException e)
+      {
+        Log.e(TAG, e.getMessage(), e);
+      }
+      return null;
+    }
+
+    // JS helper
+    public String getVersion()
+    {
+      String versionName = null;
+      try
+      {
+        versionName = getPackageManager().getPackageInfo(getPackageName(), 0).versionName;
+      }
+      catch (NameNotFoundException ex)
+      {
+        versionName = "n/a";
+      }
+      return versionName;
+    }
+
+    // JS helper
+    @SuppressWarnings("unused")
+    public boolean canAutoupdate()
+    {
+      final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+      final int refresh = Integer.valueOf(prefs.getString(getString(R.string.pref_refresh), Integer.toString(context.getResources().getInteger(R.integer.def_refresh))));
+      final boolean wifionly = prefs.getBoolean(getString(R.string.pref_wifirefresh), getResources().getBoolean(R.bool.def_wifirefresh));
+      return refresh == 2 && (!wifionly || isWiFiConnected(context));
+    }
+
+    // JS helper
+    @SuppressWarnings("unused")
+    public void httpSend(final String method, final String url, final String[][] headers, final boolean async, final long callback)
+    {
+      Log.d(TAG, "httpSend('" + method + "', '" + url + "')");
+      messageHandler.post(new Runnable()
+      {
+        @Override
+        public void run()
+        {
+          try
+          {
+            Task task = new Task();
+            task.callback = callback;
+            task.connection = (HttpURLConnection) new URL(url).openConnection();
+            task.connection.setRequestMethod(method);
+            for (int i = 0; i < headers.length; i++)
+            {
+              task.connection.setRequestProperty(headers[i][0], headers[i][1]);
+            }
+            DownloadTask downloadTask = new DownloadTask(context);
+            downloadTask.execute(task);
+            if (!async)
+            {
+              downloadTask.get();
+            }
+          }
+          catch (Exception e)
+          {
+            Log.e(TAG, e.getMessage(), e);
+            js.callback(callback, null);
+          }
+        }
+      });
+    }
+
+    // JS helper
+    @SuppressWarnings("unused")
+    public void setStatus(String text, long time)
+    {
+      sendBroadcast(new Intent(BROADCAST_SUBSCRIPTION_STATUS).putExtra("text", text).putExtra("time", time));
+    }
+
+    // JS helper
+    @SuppressWarnings("unused")
+    public void showToast(String text)
+    {
+      Log.d(TAG, "Toast: " + text);
+      Message msg = messageHandler.obtainMessage(MSG_TOAST);
+      Bundle data = new Bundle();
+      data.putString("message", text);
+      msg.setData(data);
+      messageHandler.sendMessage(msg);
+    }
+
+    // JS helper
+    @SuppressWarnings("unused")
+    public void notify(long delay)
+    {
+      if (this.delay < 0 || delay < this.delay)
+      {
+        this.delay = delay;
+        synchronized (queue)
+        {
+          queue.notify();
+        }
+      }
+    }
+
+    public Object evaluate(String script)
+    {
+      return jsEngine.evaluate(script);
+    }
+
+    public void callback(long callback, Object[] params)
+    {
+      jsEngine.callback(callback, params);
+    }
+
+    public final void stopEngine()
+    {
+      run = false;
+      synchronized (queue)
+      {
+        queue.notify();
+      }
+    }
+
+    public void execute(Runnable r)
+    {
+      synchronized (queue)
+      {
+        queue.addLast(r);
+        queue.notify();
+      }
+    }
+
+    public <T> Future<T> submit(Callable<T> callable)
+    {
+      FutureTask<T> ftask = new FutureTask<T>(callable);
+      execute(ftask);
+      return ftask;
+    }
+
+    @Override
+    public final void run()
+    {
+      jsEngine = new JSEngine(this);
+
+      jsEngine.put("_locale", Locale.getDefault().toString());
+      jsEngine.put("_datapath", getFilesDir().getAbsolutePath());
+      jsEngine.put("_separator", File.separator);
+      jsEngine.put("_version", getVersion());
+
+      try
+      {
+        jsEngine.evaluate("Android.load(\"start.js\");");
+      }
+      catch (Exception e)
+      {
+        Log.e(TAG, e.getMessage(), e);
+      }
+
+      while (run)
+      {
+        try
+        {
+          Runnable r = null;
+          synchronized (queue)
+          {
+            r = queue.poll();
+          }
+          if (r != null)
+          {
+            r.run();
+          }
+          else if (delay > 0)
+          {
+            long t = SystemClock.uptimeMillis();
+            synchronized (queue)
+            {
+              try
+              {
+                queue.wait(delay);
+              }
+              catch (InterruptedException e)
+              {
+              }
+            }
+            delay -= SystemClock.uptimeMillis() - t;
+          }
+          else if (delay <= 0)
+          {
+            delay = jsEngine.runCallbacks();
+          }
+          else
+          {
+            synchronized (queue)
+            {
+              try
+              {
+                queue.wait();
+              }
+              catch (InterruptedException e)
+              {
+                Log.e(TAG, e.getMessage(), e);
+              }
+            }
+          }
+        }
+        catch (Exception e)
+        {
+          Log.e(TAG, e.getMessage(), e);
+        }
+      }
+
+      jsEngine.release();
+    }
+  }
+
+  /**
+   * Helper class for XMLHttpRequest implementation.
+   */
+  private class Task
+  {
+    HttpURLConnection connection;
+    long callback;
+  }
+
+  /**
+   * Helper class for XMLHttpRequest implementation.
+   */
+  private class Result
+  {
+    long callback;
+    int code;
+    String message;
+    String data;
+    Map<String, List<String>> headers;
+  }
+
+  /**
+   * Helper class for XMLHttpRequest implementation.
+   */
+  private class DownloadTask extends AsyncTask<Task, Integer, Result>
+  {
+    public DownloadTask(Context context)
+    {
+    }
+
+    @Override
+    protected void onPreExecute()
+    {
+    }
+
+    @Override
+    protected void onPostExecute(Result result)
+    {
+      if (result != null)
+      {
+        final long callback = result.callback;
+        final Object[] params = new Object[4];
+
+        String[][] headers = null;
+        if (result.headers != null)
+        {
+          headers = new String[result.headers.size()][2];
+          int i = 0;
+          for (String header : result.headers.keySet())
+          {
+            headers[i][0] = header;
+            headers[i][1] = StringUtils.join(result.headers.get(header).toArray(), "; ");
+            i++;
+          }
+        }
+        params[0] = result.code;
+        params[1] = result.message;
+        params[2] = headers;
+        params[3] = result.data;
+        js.execute(new Runnable()
+        {
+          @Override
+          public void run()
+          {
+            js.callback(callback, params);
+          }
+
+        });
+      }
+    }
+
+    @Override
+    protected void onCancelled()
+    {
+    }
+
+    @Override
+    protected Result doInBackground(Task... tasks)
+    {
+      Task task = tasks[0];
+      Result result = new Result();
+      result.callback = task.callback;
+      try
+      {
+        HttpURLConnection connection = task.connection;
+        connection.connect();
+        int lenghtOfFile = connection.getContentLength();
+        Log.d("D", "S: " + lenghtOfFile);
+
+        result.code = connection.getResponseCode();
+        result.message = connection.getResponseMessage();
+        result.headers = connection.getHeaderFields();
+
+        // download the file
+        String encoding = connection.getContentEncoding();
+        if (encoding == null)
+          encoding = "utf-8";
+        BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream(), encoding));
+
+        final char[] buffer = new char[0x10000];
+        StringBuilder out = new StringBuilder();
+        long total = 0;
+        int read;
+        do
+        {
+          read = in.read(buffer, 0, buffer.length);
+          if (read > 0)
+          {
+            out.append(buffer, 0, read);
+            total += read;
+            publishProgress((int) (total * 100. / lenghtOfFile));
+          }
+        }
+        while (!isCancelled() && read >= 0);
+        result.data = out.toString();
+        in.close();
+      }
+      catch (Exception e)
+      {
+        Log.e(TAG, e.getMessage(), e);
+        result.data = "";
+        result.code = HttpURLConnection.HTTP_INTERNAL_ERROR;
+        result.message = e.toString();
+      }
+      return result;
+    }
+
+    protected void onProgressUpdate(Integer... progress)
+    {
+      Log.d("HTTP", "Progress: " + progress[0].intValue());
+    }
+  }
+}