Android GCM activity (requires AndroidAnnotations)

GCMActivity

import android.app.Activity;
import android.content.SharedPreferences;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.preference.PreferenceManager;
import android.util.Log;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.gcm.GoogleCloudMessaging;
import org.androidannotations.annotations.AfterInject;
import org.androidannotations.annotations.Background;
import org.androidannotations.annotations.EActivity;
import org.androidannotations.annotations.UiThread;

import java.io.IOException;

@EActivity
public abstract class GCMActivity extends Activity {

    private static final String TAG = GCMActivity.class.getSimpleName();
    private static final String PREF_KEY_GCM_REGISTRATION_ID = "pref_key_gcm_registration_id";
    private static final String PREF_KEY_APP_VERSION = "pref_key_app_version";
    private final static int PLAY_SERVICES_RESOLUTION_REQUEST = 9000;

    @AfterInject
    protected void afterInject() {
        if (isPlayServicesAvailable() && getStoredRegistrationId().isEmpty())
            setupGCM(getGCMSenderId());
    }

    protected boolean isPlayServicesAvailable() {
        int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (resultCode != ConnectionResult.SUCCESS) {
            if (GooglePlayServicesUtil.isUserRecoverableError(resultCode)) {
                GooglePlayServicesUtil.getErrorDialog(resultCode, this, PLAY_SERVICES_RESOLUTION_REQUEST).show();
            } else {
                Log.d(TAG, "This device is not supported.");
                finish();
            }
            return false;
        }
        return true;
    }

    protected String getStoredRegistrationId() {
        String registrationId = PreferenceManager.getDefaultSharedPreferences(this).getString(PREF_KEY_GCM_REGISTRATION_ID, "");
        if (registrationId.isEmpty()) {
            Log.d(TAG, "GCM registration ID not found.");
            return "";
        }
        if (getOldAppVersion() != getCurrentAppVersion()) {
            Log.d(TAG, "App version changed.");
            return "";
        }
        return registrationId;
    }

    private int getOldAppVersion() {
        return PreferenceManager.getDefaultSharedPreferences(this).getInt(PREF_KEY_APP_VERSION, Integer.MIN_VALUE);
    }

    private int getCurrentAppVersion() {
        try {
            PackageInfo packageInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
            return packageInfo.versionCode;
        } catch (PackageManager.NameNotFoundException e) {
            throw new RuntimeException("Could not get package name: " + e);
        }
    }

    @Background
    protected void setupGCM(String senderId) {
        try {
            setupGCMSuccess(GoogleCloudMessaging.getInstance(this).register(senderId));
        } catch (IOException e) {
            Log.e(TAG, e.getMessage());
            setupGCMError();
        }
    }

    @UiThread
    protected void setupGCMError() {
    }

    @UiThread
    protected void setupGCMSuccess(String registrationId) {
        SharedPreferences.Editor edit = PreferenceManager.getDefaultSharedPreferences(this).edit();
        edit.putString(PREF_KEY_GCM_REGISTRATION_ID, registrationId);
        edit.putInt(PREF_KEY_APP_VERSION, getCurrentAppVersion());
        edit.commit();
        sendGCMRegistrationIdToBackend(registrationId);
    }

    @Background
    protected abstract void sendGCMRegistrationIdToBackend(String registrationId);

    protected abstract String getGCMSenderId();

}