NetworkEventDispatcher.java revision b1e60e2015b81c285938ca569b66edda63d6533d 
1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package libcore.net.event;
18
19import java.util.List;
20import java.util.concurrent.CopyOnWriteArrayList;
21
22/**
23 * A singleton used to dispatch network events to registered listeners.
24 */
25public class NetworkEventDispatcher {
26
27  private static final NetworkEventDispatcher instance = new NetworkEventDispatcher();
28
29  private final List<NetworkEventListener> listeners =
30      new CopyOnWriteArrayList<NetworkEventListener>();
31
32  /**
33   * Returns the shared {@link NetworkEventDispatcher} instance.
34   */
35  public static NetworkEventDispatcher getInstance() {
36    return instance;
37  }
38
39  /** Visible for testing. Use {@link #getInstance()} instead. */
40  protected NetworkEventDispatcher() {
41  }
42
43  /**
44   * Registers a listener to be notified when network events occur.
45   * It can be deregistered using {@link #removeListener(NetworkEventListener)}
46   */
47  public void addListener(NetworkEventListener toAdd) {
48    if (toAdd == null) {
49      throw new NullPointerException("toAdd == null");
50    }
51    listeners.add(toAdd);
52  }
53
54  /**
55   * De-registers a listener previously added with {@link #addListener(NetworkEventListener)}. If
56   * the listener was not previously registered this is a no-op.
57   */
58  public void removeListener(NetworkEventListener toRemove) {
59    for (NetworkEventListener listener : listeners) {
60      if (listener == toRemove) {
61        listeners.remove(listener);
62        return;
63      }
64    }
65  }
66
67  /**
68   * Notifies registered listeners of a network configuration change.
69   */
70  public void onNetworkConfigurationChanged() {
71    for (NetworkEventListener listener : listeners) {
72      try {
73        listener.onNetworkConfigurationChanged();
74      } catch (RuntimeException e) {
75        System.logI("Exception thrown during network event propagation", e);
76      }
77    }
78  }
79}
80