Android Open Source - MentorMe Notification Center

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License

The source code is released under:
MIT License
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Java Source Code

package com.codepath.wwcmentorme.helpers;
/*from   ww  w  . java2s.  co m*/
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;

import com.pubnub.api.Callback;
import com.pubnub.api.Pubnub;
import com.pubnub.api.PubnubException;

public class NotificationCenter {
  private static String PUBNUB_PREFIX = "pubnub_";
  public static interface Listener<V> {
    public void didChange(final String key, final V oldValue, final V newValue);
  }
  
  final static HashMap<String, ArrayList<WeakReference<Listener<? extends Object>>>> sMap = new HashMap<String, ArrayList<WeakReference<Listener<? extends Object>>>>();
  
  public static void registerListener(final Listener<? extends Object> listener, final String key) {
    if (!sMap.containsKey(key)) {
      final ArrayList<WeakReference<Listener<? extends Object>>> references = new ArrayList<WeakReference<Listener<? extends Object>>>();
      sMap.put(key, references);
    }
    final ArrayList<WeakReference<Listener<? extends Object>>> references = sMap.get(key);
    prune(key);
    if (indexOf(references, listener) < 0) {
      references.add(new WeakReference<NotificationCenter.Listener<? extends Object>>(listener));
    }
    if (key.startsWith(PUBNUB_PREFIX)) {
      subscribe(key);
    }
  }
  
  private static void prune(final String key) {
    final ArrayList<WeakReference<Listener<? extends Object>>> references = sMap.get(key);
    if (references == null) return;
    final ArrayList<WeakReference<Listener<? extends Object>>> referencesToRemove = new ArrayList<WeakReference<Listener<? extends Object>>>();
    for (final WeakReference<Listener<? extends Object>> weakReference : references) {
      if (weakReference.get() == null) referencesToRemove.add(weakReference);
    }
    references.removeAll(referencesToRemove);
    if (key.startsWith(PUBNUB_PREFIX)) {
      if (references.size() == 0) {
        unsubscribe(key);
      }
    }
  }
  
  private static void pruneAll() {
    for (final String key : sMap.keySet()) {
      prune(key);
    }
  }
  
  private static int indexOf(final ArrayList<WeakReference<Listener<? extends Object>>> references, final Listener<? extends Object> reference) {
    int index = 0;
    for (final WeakReference<Listener<? extends Object>> weakReference : references) {
      if (weakReference.get() == reference) return index;
      ++index;
    }
    return -1;
  }
  
  public static void unregisterListener(final Listener<? extends Object> listener, final String key) {
    final ArrayList<WeakReference<Listener<? extends Object>>> references = sMap.get(key);
    if (references != null) {
      final int index = indexOf(references, listener);
      if (index > 0) {
        references.remove(index);
      }
    }
  }
  
  public static <V> void broadcastChange(final String key, final V oldValue, final V newValue) {
    if (key.startsWith(PUBNUB_PREFIX)) {
      publish(key, "");
    } else {
      broadcastChangeToReferences(key, oldValue, newValue);
    }
  }
  
  private static <V> void broadcastChangeToReferences(final String key, final V oldValue, final V newValue) {
    final ArrayList<WeakReference<Listener<? extends Object>>> references = sMap.get(key);
    if (references == null) return;
    for (final WeakReference<Listener<? extends Object>> weakReference : references) {
      final Listener<V> listener = (Listener<V>)weakReference.get();
      if (listener != null) {
        listener.didChange(key, oldValue, newValue);
      }
    }
  }
  
  private static Pubnub sPubnub = new Pubnub("pub-c-5b029b3f-1a53-49ba-8dde-9c63b99fc0f9", "sub-c-3e884ebc-d933-11e3-a226-02ee2ddab7fe");
  
  public static String keyForPubnubChannel(final String channel) {
    return PUBNUB_PREFIX + channel;
  }
  
  private static HashSet<String> sSubscribedChannels = new HashSet<String>();
  
  private static void subscribe(final String channel) {
    if (sSubscribedChannels.contains(channel)) return;
    final Pubnub pubnub = sPubnub;
    try {
      pubnub.subscribe(channel, new Callback() {
        @Override
        public void successCallback(String channel, Object payload) {
          broadcastChangeToReferences(channel, null, null);
        }
      });
      sSubscribedChannels.add(channel);
    } catch (PubnubException e) {
      e.printStackTrace();
    }
  }
  
  private static void unsubscribe(final String channel) {
    sSubscribedChannels.remove(channel);
    final Pubnub pubnub = sPubnub;
    pubnub.unsubscribe(channel);
  }
  
  private static void publish(final String channel, final String payload) {
    final Pubnub pubnub = sPubnub;
    pubnub.publish(channel, payload, new Callback() {
      @Override
      public void successCallback(String arg0, Object arg1) {
      }
    });
  }
}
Java Source Code List
