Subscription count event

CHANGELOG.md

@@ -1,5 +1,8 @@
 # pusher-websocket-java changelog
 
+### Version 2.4.0 - 15th July 2022
+* Add support for Subscription count events
+
 ### Version 2.3.0 - 4th July 2022
 * Added support for user sign in and server to user messages
 * Fixed issue with calling disconnect while the client is attempting reconnection

README.md

@@ -74,7 +74,7 @@ The pusher-java-client is available in Maven Central.
  <dependency>
  <groupId>com.pusher</groupId>
  <artifactId>pusher-java-client</artifactId>
- <version>2.3.0-beta</version>
+ <version>2.4.0</version>
  </dependency>
 </dependencies>
 ```
@@ -83,7 +83,7 @@ The pusher-java-client is available in Maven Central.
 
 ```groovy
 dependencies {
- compile 'com.pusher:pusher-java-client:2.3.0-beta'
+ compile 'com.pusher:pusher-java-client:2.3.1'
 }
 ```
 
@@ -256,6 +256,19 @@ Channel channel = pusher.subscribe("my-channel", new ChannelEventListener() {
 
  // Other ChannelEventListener methods
 });
+```
+If you wish to be informed for subscription count events, pass an implementation of the `ChannelEventListener` interface:
+
+```java
+Channel channel = pusher.subscribe("my-channel", new ChannelEventListener() {
+ @Override
+ public void onSubscriptionCountChanged(String channelName, int count) {
+ System.out.println("Members in channel: " + channelName + " are: " + count);
+ }
+
+ // Other ChannelEventListener methods
+});
+
 ```
 
 ### Private channels

build.gradle

@@ -26,7 +26,7 @@ def getProperty = { property ->
 }
 
 group = "com.pusher"
-version = "2.3.0-beta"
+version = "2.4.0"
 sourceCompatibility = "1.8"
 targetCompatibility = "1.8"
 

src/main/java/com/pusher/client/channel/ChannelEventListener.java

@@ -40,4 +40,19 @@ public interface ChannelEventListener extends SubscriptionEventListener {
  * The name of the channel that was successfully subscribed.
  */
  void onSubscriptionSucceeded(String channelName);
+
+ /**
+ * <p>
+ * Callback fired when a subscription success count
+ * of a channel changes
+ * </p>
+ *
+ *
+ * @param channelName
+ * The name of the channel for which the count changed.
+ * 
+ * @param count
+ * The latest count of subscribers on the channel.
+ */
+ void onSubscriptionCountChanged(String channelName, int count);
 }

src/main/java/com/pusher/client/channel/impl/BaseChannel.java

@@ -2,7 +2,6 @@
 
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Set;
 
@@ -11,19 +10,22 @@
 import com.google.gson.GsonBuilder;
 import com.pusher.client.channel.*;
 import com.pusher.client.channel.impl.message.SubscribeMessage;
+import com.pusher.client.channel.impl.message.SubscriptionCountData;
 import com.pusher.client.channel.impl.message.UnsubscribeMessage;
 import com.pusher.client.util.Factory;
 
 public abstract class BaseChannel implements InternalChannel {
  protected final Gson GSON;
  private static final String INTERNAL_EVENT_PREFIX = "pusher_internal:";
  protected static final String SUBSCRIPTION_SUCCESS_EVENT = "pusher_internal:subscription_succeeded";
+ protected static final String SUBSCRIPTION_COUNT_EVENT = "pusher_internal:subscription_count";
  private Set<SubscriptionEventListener> globalListeners = new HashSet<SubscriptionEventListener>();
  private final Map<String, Set<SubscriptionEventListener>> eventNameToListenerMap = new HashMap<String, Set<SubscriptionEventListener>>();
  protected volatile ChannelState state = ChannelState.INITIAL;
  private ChannelEventListener eventListener;
  private final Factory factory;
  private final Object lock = new Object();
+ private Integer subscriptionCount;
 
  public BaseChannel(final Factory factory) {
  GsonBuilder gsonBuilder = new GsonBuilder();
@@ -37,6 +39,11 @@ public BaseChannel(final Factory factory) {
  @Override
  abstract public String getName();
 
+ @Override
+ public Integer getCount() {
+ return subscriptionCount;
+ }
+
  @Override
  public void bind(final String eventName, final SubscriptionEventListener listener) {
  validateArguments(eventName, listener);
@@ -112,6 +119,8 @@ public PusherEvent prepareEvent(String event, String message) {
  public void onMessage(String event, String message) {
  if (event.equals(SUBSCRIPTION_SUCCESS_EVENT)) {
  updateState(ChannelState.SUBSCRIBED);
+ }else if (event.equals(SUBSCRIPTION_COUNT_EVENT)) {
+ handleSubscriptionCountEvent(message);
  } else {
  final Set<SubscriptionEventListener> listeners = getInterestedListeners(event);
  if (listeners != null) {
@@ -184,6 +193,20 @@ private void validateArguments(final String eventName, final SubscriptionEventLi
  }
  }
 
+ private void handleSubscriptionCountEvent(final String message) {
+ String channelName = getName();
+ final SubscriptionCountData subscriptionCountMessage = GSON.fromJson(message, SubscriptionCountData.class);
+ subscriptionCount = subscriptionCountMessage.getCount();
+ if (eventListener != null ) {
+ factory.queueOnEventThread(new Runnable() {
+ @Override
+ public void run() {
+ eventListener.onSubscriptionCountChanged(channelName, subscriptionCountMessage.getCount());
+ }
+ });
+ }
+ }
+
  protected Set<SubscriptionEventListener> getInterestedListeners(String event) {
  synchronized (lock) {
  Set<SubscriptionEventListener> listeners = new HashSet<SubscriptionEventListener>();

src/main/java/com/pusher/client/channel/impl/InternalChannel.java

@@ -11,6 +11,8 @@ public interface InternalChannel extends Channel, Comparable<InternalChannel> {
 
  String toUnsubscribeMessage();
 
+ Integer getCount();
+
  PusherEvent prepareEvent(String event, String message);
 
  void onMessage(String event, String message);

src/main/java/com/pusher/client/channel/impl/message/SubscriptionCountData.java

@@ -0,0 +1,12 @@
+package com.pusher.client.channel.impl.message;
+
+import com.google.gson.annotations.SerializedName;
+
+public class SubscriptionCountData {
+ @SerializedName("subscription_count")
+ public Integer count;
+
+ public int getCount(){
+ return count;
+ }
+}

src/main/java/com/pusher/client/example/ExampleApp.java

@@ -78,6 +78,12 @@ public void onEvent(PusherEvent event) {
  System.out.println(String.format(
  "Received event [%s]", event.toString()));
  }
+
+ @Override
+ public void onSubscriptionCountChanged(String channelName, int count) {
+ System.out.println(String.format(
+ "Count for channel [%s], changed to [%d]", channelName, count));
+ }
  };
 
  // subscribe to the channel and with the event listener for the event name

src/main/java/com/pusher/client/example/PresenceChannelExampleApp.java

@@ -115,6 +115,12 @@ public void userUnsubscribed(String channelName, User user) {
  System.out.println(String.format("A user has left channel [%s]: %s", channelName, user));
  printCurrentlySubscribedUsers();
  }
+
+ @Override
+ public void onSubscriptionCountChanged(String channelName, int count) {
+ System.out.println(String.format(
+ "Count for channel [%s], changed to [%d]", channelName, count));
+ }
  };
 
  // subscribe to the channel and with the event listener for the event name

src/main/java/com/pusher/client/example/PrivateChannelExampleApp.java

@@ -94,6 +94,12 @@ public void onAuthenticationFailure(String message, Exception e) {
  System.out.println(String.format(
  "Authorization failure due to [%s], exception was [%s]", message, e));
  }
+
+ @Override
+ public void onSubscriptionCountChanged(String channelName, int count) {
+ System.out.println(String.format(
+ "Count for channel [%s], changed to [%d]", channelName, count));
+ }
  };
 
  // subscribe to the channel and with the event listener for the event name

src/main/java/com/pusher/client/example/PrivateEncryptedChannelExampleApp.java

@@ -106,6 +106,12 @@ public void onDecryptionFailure(String event, String reason) {
  System.out.println(String.format(
  "An error was received decrypting message for event:[%s] - reason: [%s]", event, reason));
  }
+
+ @Override
+ public void onSubscriptionCountChanged(String channelName, int count) {
+ System.out.println(String.format(
+ "Count for channel [%s], changed to [%d]", channelName, count));
+ }
  };
 
  // subscribe to the channel and with the event listener for the event name