UpdateCheckerService.java

package org.exobel.routerkeygen;

import android.app.IntentService;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.support.v4.app.NotificationCompat;

import org.exobel.routerkeygen.ui.Preferences;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;

public class UpdateCheckerService extends IntentService {

    private final static String URL_DOWNLOAD = "https://raw.githubusercontent.com/routerkeygen/routerkeygenAndroid/master/android/routerkeygen_version.json";
    // Unique Identification Number for the Notification.
    // We use it on Notification start, and to cancel it.
    private final int UNIQUE_ID = R.string.app_name
            + UpdateCheckerService.class.getName().hashCode();

    public UpdateCheckerService() {
        super("UpdateCheckerService");
    }

    public static LastVersion getLatestVersion() {
        try {
            final JSONObject version = getRemoteObjectAsJson(new URL(
                    URL_DOWNLOAD));
            if (version == null) {
                return null;
            }
            final LastVersion lV = new LastVersion();
            lV.version = version.getString("version");
            lV.url = version.getString("url");
            return lV;
        } catch (JSONException | MalformedURLException e) {
            e.printStackTrace();
        }
        return null;
    }

    private static JSONObject getRemoteObjectAsJson(URL url) {
        InputStream inputStream = null;
        try {
            byte[] buffer = new byte[128];
            int read;
            String jsonAsString = "";

            inputStream = url.openStream();

            do {
                read = inputStream.read(buffer);
                if (read > 0) {
                    jsonAsString += new String(buffer, 0, read);
                }
            } while (read > -1);

            return new JSONObject(jsonAsString);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        } finally {
            if (inputStream != null)
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }

    }

    @Override
    protected void onHandleIntent(Intent intent) {
        NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        final LastVersion lastVersion = getLatestVersion();
        if (lastVersion == null)
            return;
        if (!Preferences.VERSION.equals(lastVersion.version)) {
            final NotificationCompat.Builder builder = new NotificationCompat.Builder(
                    this)
                    .setSmallIcon(R.drawable.ic_notification)
                    .setTicker(getString(R.string.update_title))
                    .setContentTitle(getString(R.string.update_title))
                    .setContentText(
                            getString(R.string.update_notification,
                                    lastVersion.version))
                    .setOnlyAlertOnce(true)
                    .setAutoCancel(true)
                    .setContentIntent(
                            PendingIntent.getActivity(getApplicationContext(),
                                    0,
                                    new Intent(Intent.ACTION_VIEW).setData(Uri
                                            .parse(lastVersion.url)),
                                    PendingIntent.FLAG_ONE_SHOT));
            mNotificationManager.notify(UNIQUE_ID, builder.build());
        }
    }

    public static class LastVersion {
        public String version;
        public String url;
    }
}