CloudBackendActivity.java

/*
 * Copyright (c) 2013 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.cloud.backend.android;

import java.util.List;

import android.app.Activity;
import android.os.Bundle;

/**
 * An {@link Activity} class that wraps CloudBackend features including CRUD of
 * {@link CloudEntity}, Google account authentication and Google Cloud
 * Messaging. Developer may create a subclass to use these features. If you want
 * to inherit other {@link Activity} subclasses, you may rewrite the superclass
 * name of the class definition below.
 * 
 */
public class CloudBackendActivity extends Activity {

    private CloudBackendMessaging cloudBackend;

    // is this app subscribed to the Cloud Message?
    private static boolean isSubscribedToBroadcastMessage = false;

    /**
     * Returns {@link CloudBackendMessaging} instance for this activity.
     * 
     * @return {@link CloudBackendMessaging}
     */
    protected CloudBackendMessaging getCloudBackend() {
        return cloudBackend;
    }

    /**
     * Subclasses may override this to execute initialization of the activity.
     * If it uses any CloudBackend features, it should be executed inside
     * {@link #onPostCreate()} that will be called after CloudBackend
     * initializations such as user authentication.
     */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // init backend
        cloudBackend = new CloudBackendMessaging(this);

        // post create initialization
        _onPostCreate();
    }

    private void _onPostCreate() {
        // init subscription to broadcast message
        if (!isSubscribedToBroadcastMessage) {
            isSubscribedToBroadcastMessage = true;
            CloudCallbackHandler<List<CloudEntity>> handler = new CloudCallbackHandler<List<CloudEntity>>() {
                @Override
                public void onComplete(List<CloudEntity> results) {
                    onBroadcastMessageReceived(results);
                }
            };
            cloudBackend.subscribeToCloudMessage(CloudBackendMessaging.TOPIC_ID_BROADCAST, handler);
        }

        // call onPostCreate
        onPostCreate();
    }

    /**
     * Will be called after initialization process including the account
     * picking. Subclasses may override to execute any initialization of the
     * activity.
     */
    protected void onPostCreate() {
    }

    /**
     * Handles broadcast messages from the backend. Subclasses may override this
     * to handle the message accordingly.
     * 
     * @param message
     *            {@link CloudEntity} that contains the message values.
     */
    public void onBroadcastMessageReceived(List<CloudEntity> message) {
    }
}