Merge pull request #210 from marschall/ConcurrentModificationException

Clean up Whiteboard Sample

Author: arun-gupta

websocket/whiteboard/src/main/java/org/javaee7/websocket/whiteboard/FigureDecoder.java

@@ -40,6 +40,9 @@
 package org.javaee7.websocket.whiteboard;
 
 import java.io.StringReader;
+import java.lang.invoke.MethodHandles;
+import java.util.logging.Logger;
+
 import javax.json.Json;
 import javax.json.JsonException;
 import javax.json.JsonObject;
@@ -51,9 +54,12 @@
  * @author Arun Gupta
  */
 public class FigureDecoder implements Decoder.Text<Figure> {
+
+    private static final Logger LOGGER = Logger.getLogger(MethodHandles.lookup().lookupClass().getName());
+
     @Override
     public Figure decode(String string) throws DecodeException {
-        System.out.println("decoding: " + string);
+        LOGGER.info("decoding: " + string);
         JsonObject jsonObject = Json.createReader(new StringReader(string)).readObject();
         return new Figure(jsonObject);
     }
@@ -71,11 +77,11 @@ public boolean willDecode(String string) {
 
     @Override
     public void init(EndpointConfig ec) {
-        System.out.println("init");
+        LOGGER.info("init");
     }
 
     @Override
     public void destroy() {
-        System.out.println("desroy");
+        LOGGER.info("destroy");
     }
 }

websocket/whiteboard/src/main/java/org/javaee7/websocket/whiteboard/FigureEncoder.java

@@ -39,6 +39,9 @@
  */
 package org.javaee7.websocket.whiteboard;
 
+import java.lang.invoke.MethodHandles;
+import java.util.logging.Logger;
+
 import javax.websocket.EncodeException;
 import javax.websocket.Encoder;
 import javax.websocket.EndpointConfig;
@@ -47,18 +50,21 @@
  * @author Arun Gupta
  */
 public class FigureEncoder implements Encoder.Text<Figure> {
+
+    private static final Logger LOGGER = Logger.getLogger(MethodHandles.lookup().lookupClass().getName());
+    
     @Override
     public String encode(Figure figure) throws EncodeException {
         return figure.getJson().toString();
     }
 
     @Override
     public void init(EndpointConfig ec) {
-        System.out.println("init");
+        LOGGER.info("init");
     }
 
     @Override
     public void destroy() {
-        System.out.println("desroy");
+        LOGGER.info("destroy");
     }
 }

websocket/whiteboard/src/main/java/org/javaee7/websocket/whiteboard/Whiteboard.java

@@ -40,10 +40,12 @@
 package org.javaee7.websocket.whiteboard;
 
 import java.io.IOException;
+import java.lang.invoke.MethodHandles;
 import java.nio.ByteBuffer;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.logging.Logger;
+
 import javax.websocket.EncodeException;
 import javax.websocket.OnClose;
 import javax.websocket.OnMessage;
@@ -59,11 +61,15 @@
         decoders = {FigureDecoder.class})
 public class Whiteboard {
 
-    private static final Set<Session> peers = Collections.synchronizedSet(new HashSet<Session>());
+    private static final Logger LOGGER = Logger.getLogger(MethodHandles.lookup().lookupClass().getName());
+
+    private static final Object PRESENT = new Object();
+    
+    private static final ConcurrentMap<Session, Object> peers = new ConcurrentHashMap<>();
 
     @OnOpen
     public void onOpen(Session peer) {
-        peers.add(peer);
+        peers.put(peer, PRESENT);
     }
 
     @OnClose
@@ -73,8 +79,8 @@ public void onClose(Session peer) {
 
     @OnMessage
     public void broadcastFigure(Figure figure, Session session) throws IOException, EncodeException {
-        System.out.println("boradcastFigure: " + figure);
-        for (Session peer : peers) {
+        LOGGER.info("boradcastFigure: " + figure);
+        for (Session peer : peers.keySet()) {
             if (!peer.equals(session)) {
                 peer.getBasicRemote().sendObject(figure);
             }
@@ -83,8 +89,8 @@ public void broadcastFigure(Figure figure, Session session) throws IOException,
 
     @OnMessage
     public void broadcastSnapshot(ByteBuffer data, Session session) throws IOException {
-        System.out.println("broadcastBinary: " + data);
-        for (Session peer : peers) {
+        LOGGER.info("broadcastBinary: " + data);
+        for (Session peer : peers.keySet()) {
             if (!peer.equals(session)) {
                 peer.getBasicRemote().sendBinary(data);
             }