com.google.cloud.backend.android.CloudBackendActivity.java Source code

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Here is the source code for com.google.cloud.backend.android.CloudBackendActivity.java

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/*
 * 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.accounts.AccountManager;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;

import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;

/**
 * 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 FragmentActivity {

    private static final int REQUEST_ACCOUNT_PICKER = 2;

    private static final String PREF_KEY_ACCOUNT_NAME = "PREF_KEY_ACCOUNT_NAME";

    private GoogleAccountCredential credential;

    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 return false if the app need to disable
     * authentication.
     */
    public boolean isAuthEnabled() {
        return Consts.IS_AUTH_ENABLED;
    }

    /**
     * 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);

        // create credential
        credential = GoogleAccountCredential.usingAudience(this, Consts.AUTH_AUDIENCE);
        cloudBackend.setCredential(credential);

        // if auth enabled, get account name from the shared pref
        if (isAuthEnabled()) {
            String accountName = cloudBackend.getSharedPreferences().getString(PREF_KEY_ACCOUNT_NAME, null);
            if (accountName == null) {
                // let user pick an account
                super.startActivityForResult(credential.newChooseAccountIntent(), REQUEST_ACCOUNT_PICKER);
                return; // continue init in onActivityResult
            } else {
                credential.setSelectedAccountName(accountName);
            }
        }

        // 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
        this.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) {
    }

    /**
     * Handles callback from Intents like authorization request or account
     * picking.
     */
    @Override
    protected final void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        switch (requestCode) {
        case REQUEST_ACCOUNT_PICKER:
            if (data != null && data.getExtras() != null) {

                // set the picked account name to the credential
                String accountName = data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
                credential.setSelectedAccountName(accountName);

                // save account name to shared pref
                SharedPreferences.Editor e = cloudBackend.getSharedPreferences().edit();
                e.putString(PREF_KEY_ACCOUNT_NAME, accountName);
                e.commit();
            }

            // post create initialization
            _onPostCreate();
            break;
        }
    }

    /**
     * Returns account name selected by user, or null if any account is selected.
     */
    protected String getAccountName() {
        return credential == null ? null : credential.getSelectedAccountName();
    }
}