Java tutorial
/** * Copyright (c) 2014-present, Facebook, Inc. All rights reserved. * * You are hereby granted a non-exclusive, worldwide, royalty-free license to use, * copy, modify, and distribute this software in source code or binary form for use * in connection with the web services and APIs provided by Facebook. * * As with any software that integrates with the Facebook platform, your use of * this software is subject to the Facebook Developer Principles and Policies * [http://developers.facebook.com/policy/]. This copyright notice shall be * included in all copies or substantial portions of the software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ package com.facebook; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.support.v4.content.LocalBroadcastManager; import com.facebook.internal.Validate; /** * This class can be extended to receive notifications of access token changes. The {@link * #stopTracking()} method should be called in the onDestroy() method of the receiving Activity or * Fragment. */ public abstract class AccessTokenTracker { private final BroadcastReceiver receiver; private final LocalBroadcastManager broadcastManager; private boolean isTracking = false; /** * The method that will be called with the access token changes. * @param oldAccessToken The access token before the change. * @param currentAccessToken The new access token. */ protected abstract void onCurrentAccessTokenChanged(AccessToken oldAccessToken, AccessToken currentAccessToken); /** * The constructor. */ public AccessTokenTracker() { Validate.sdkInitialized(); this.receiver = new CurrentAccessTokenBroadcastReceiver(); this.broadcastManager = LocalBroadcastManager.getInstance(FacebookSdk.getApplicationContext()); startTracking(); } /** * Starts tracking the current access token */ public void startTracking() { if (isTracking) { return; } addBroadcastReceiver(); isTracking = true; } /** * Stops tracking the current access token. */ public void stopTracking() { if (!isTracking) { return; } broadcastManager.unregisterReceiver(receiver); isTracking = false; } /** * Gets whether the tracker is tracking the current access token. * @return true if the tracker is tracking the current access token, false if not */ public boolean isTracking() { return isTracking; } private class CurrentAccessTokenBroadcastReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { if (AccessTokenManager.ACTION_CURRENT_ACCESS_TOKEN_CHANGED.equals(intent.getAction())) { AccessToken oldAccessToken = (AccessToken) intent .getParcelableExtra(AccessTokenManager.EXTRA_OLD_ACCESS_TOKEN); AccessToken newAccessToken = (AccessToken) intent .getParcelableExtra(AccessTokenManager.EXTRA_NEW_ACCESS_TOKEN); onCurrentAccessTokenChanged(oldAccessToken, newAccessToken); } } } private void addBroadcastReceiver() { IntentFilter filter = new IntentFilter(); filter.addAction(AccessTokenManager.ACTION_CURRENT_ACCESS_TOKEN_CHANGED); broadcastManager.registerReceiver(receiver, filter); } }