| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * |
| * 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 android.location; |
| |
| import com.android.internal.util.Preconditions; |
| |
| import android.annotation.NonNull; |
| import android.content.Context; |
| import android.os.RemoteException; |
| import android.util.Log; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.HashSet; |
| |
| /** |
| * A base handler class to manage transport and local listeners. |
| * |
| * @hide |
| */ |
| abstract class LocalListenerHelper<TListener> { |
| private final HashSet<TListener> mListeners = new HashSet<>(); |
| |
| private final String mTag; |
| private final Context mContext; |
| |
| protected LocalListenerHelper(Context context, String name) { |
| Preconditions.checkNotNull(name); |
| mContext = context; |
| mTag = name; |
| } |
| |
| public boolean add(@NonNull TListener listener) { |
| Preconditions.checkNotNull(listener); |
| synchronized (mListeners) { |
| // we need to register with the service first, because we need to find out if the |
| // service will actually support the request before we attempt anything |
| if (mListeners.isEmpty()) { |
| boolean registeredWithService; |
| try { |
| registeredWithService = registerWithServer(); |
| } catch (RemoteException e) { |
| Log.e(mTag, "Error handling first listener.", e); |
| return false; |
| } |
| if (!registeredWithService) { |
| Log.e(mTag, "Unable to register listener transport."); |
| return false; |
| } |
| } |
| if (mListeners.contains(listener)) { |
| return true; |
| } |
| return mListeners.add(listener); |
| } |
| } |
| |
| public void remove(@NonNull TListener listener) { |
| Preconditions.checkNotNull(listener); |
| synchronized (mListeners) { |
| boolean removed = mListeners.remove(listener); |
| boolean isLastRemoved = removed && mListeners.isEmpty(); |
| if (isLastRemoved) { |
| try { |
| unregisterFromServer(); |
| } catch (RemoteException e) { |
| Log.v(mTag, "Error handling last listener removal", e); |
| } |
| } |
| } |
| } |
| |
| protected abstract boolean registerWithServer() throws RemoteException; |
| protected abstract void unregisterFromServer() throws RemoteException; |
| |
| protected interface ListenerOperation<TListener> { |
| void execute(TListener listener) throws RemoteException; |
| } |
| |
| protected Context getContext() { |
| return mContext; |
| } |
| |
| protected void foreach(ListenerOperation<TListener> operation) { |
| Collection<TListener> listeners; |
| synchronized (mListeners) { |
| listeners = new ArrayList<>(mListeners); |
| } |
| for (TListener listener : listeners) { |
| try { |
| operation.execute(listener); |
| } catch (RemoteException e) { |
| Log.e(mTag, "Error in monitored listener.", e); |
| // don't return, give a fair chance to all listeners to receive the event |
| } |
| } |
| } |
| } |