Beispiel für WebSocket handling mit Undertow und JavaScript

src/main/java/example/undertow/UndertowWebsocket.java

@@ -9,6 +9,8 @@
 import io.undertow.servlet.api.DeploymentInfo;
 import io.undertow.servlet.api.DeploymentManager;
 import io.undertow.websockets.WebSocketConnectionCallback;
+import io.undertow.websockets.core.AbstractReceiveListener;
+import io.undertow.websockets.core.BufferedTextMessage;
 import io.undertow.websockets.core.WebSocketChannel;
 import io.undertow.websockets.core.WebSockets;
 import io.undertow.websockets.spi.WebSocketHttpExchange;
@@ -18,29 +20,13 @@
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Iterator;
 import java.util.List;
 
 public class UndertowWebsocket {
     private static final Logger logger = LoggerFactory.getLogger(UndertowWebsocket.class);
 
     public static void main(String[] args) throws ServletException, IOException {
-        SocketHandler socketHandler = new SocketHandler();
-        new Thread(() -> {
-            while (true) {
-                try {
-                    try {
-                        Thread.sleep(10000);
-                    } catch (InterruptedException e) {
-                        break;
-                    }
-                    logger.info("Notifying channel.");
-                    socketHandler.notifyChannel();
-                } catch (Exception ignore) {
-
-                }
-            }
-        }).start();
-
         DeploymentInfo deployment = Servlets.deployment()
                 .setClassLoader(UndertowWebsocket.class.getClassLoader())
                 .setContextPath("")
@@ -51,7 +37,7 @@ public static void main(String[] args) throws ServletException, IOException {
         manager.deploy();
         HttpHandler handler = manager.start();
         PathHandler pathHandler = Handlers.path(handler)
-                .addPrefixPath("/websocket", Handlers.websocket(socketHandler));
+                .addPrefixPath("/websocket", Handlers.websocket(new SocketHandler()));
 
         Undertow server = Undertow.builder()
                 .addHttpListener(8880, "localhost")
@@ -61,19 +47,41 @@ public static void main(String[] args) throws ServletException, IOException {
         logger.info("Server started");
     }
 
-    public static class SocketHandler implements WebSocketConnectionCallback {
-        private List<WebSocketChannel> channel = new ArrayList<>();
+    public static class SocketHandler extends AbstractReceiveListener implements WebSocketConnectionCallback {
+        private final List<WebSocketChannel> channels = new ArrayList<>();
 
         @Override
         public void onConnect(WebSocketHttpExchange exchange, WebSocketChannel channel) {
             logger.info("onConnect");
-            this.channel.add(channel);
+            this.channels.add(channel);
+
+            channel.getReceiveSetter().set(this);
+            channel.resumeReceives();
         }
 
-        public void notifyChannel() {
-            for (WebSocketChannel c : channel) {
-                WebSockets.sendText("Hallo Welt!", c, null);
+        @Override
+        protected void onFullTextMessage(WebSocketChannel channel, BufferedTextMessage message) {
+            String msgText = message.getData();
+            logger.info("Received message {}", msgText);
+            notifyChannels(msgText);
+        }
+
+        public void notifyChannels(String message) {
+            int numChannelsNotified = 0;
+            int numChannelsDropped = 0;
+            Iterator<WebSocketChannel> iterator = channels.iterator();
+            while (iterator.hasNext()) {
+                WebSocketChannel channel = iterator.next();
+                if (channel.getCloseCode() >= 0) {
+                    iterator.remove();
+                    numChannelsDropped++;
+                    continue;
+                }
+
+                WebSockets.sendText(message, channel, null);
+                numChannelsNotified++;
             }
+            logger.info("Notified {} channels, dropped {} channels", numChannelsNotified, numChannelsDropped);
         }
     }
 }

src/main/java/logback/LogbackLoggerConfigurator.java

@@ -15,13 +15,13 @@
 import ch.qos.logback.core.rolling.RollingFileAppender;
 import ch.qos.logback.core.spi.ContextAwareBase;
 
+import java.util.Arrays;
 import java.util.List;
 
 public class LogbackLoggerConfigurator extends ContextAwareBase implements Configurator {
 
     private static final String LOG_FILE = "logs/jChess.log";
 
-    @SuppressWarnings("CommentedOutCode")
     @Override
     public ExecutionStatus configure(LoggerContext context) {
         ConsoleAppender<ILoggingEvent> consoleAppender = createConsoleAppender();
@@ -32,10 +32,9 @@ public ExecutionStatus configure(LoggerContext context) {
         rootLogger.addAppender(fileAppender);
 
         // if a specific package logger is too vocal, you can silence it like this:
-        /*
         List<OutputStreamAppender<ILoggingEvent>> appenders = Arrays.asList(consoleAppender, fileAppender);
-        configureLogger(context, Level.WARN, appenders, "io.undertow");
-        */
+        configureLogger(context, Level.INFO, appenders, "io.undertow");
+        configureLogger(context, Level.INFO, appenders, "org.xnio");
 
         return ExecutionStatus.DO_NOT_INVOKE_NEXT_IF_ANY;
     }

src/main/resources/webExample/websocket.html

@@ -3,18 +3,48 @@
 <head>
     <meta charset="UTF-8">
     <title>Title</title>
+    <style>
+        .message-entry {
+            left: 20px;
+            right: 20px;
+            margin: 3px;
+            padding: 3px;
+            color: white;
+        }
+    </style>
+    <script src="Templating.js"></script>
 </head>
 <body>
-  <script>
-    let socket = new WebSocket("ws://localhost:8880/websocket");
-    socket.addEventListener("open", (event) => {
-      socket.send("Hello Server!");
-    });
+    <div style="display: flex; flex-direction: column; gap: 20px; justify-content: center; align-items: center">
+        <div style="display: flex; flex-direction: row; gap: 10px; align-items: center; flex-basis: 0; width: 100%">
+            <label for="messageInput">Nachricht</label>
+            <textarea id="messageInput" name="messageInput" rows="4" style="flex-grow: 1"></textarea>
+            <button onclick="sendRequest()">Nachricht Senden</button>
+        </div>
+        <div id="messagePanel" style="display: flex; flex-direction: column; gap: 10px; background-color: #666666; border-radius: 5px; border: 1px solid #777777; width: 95vw; align-items: start">
+            <div class="message-entry" style="font-size: 1.25em;">
+                Erhaltene Nachrichten
+            </div>
+        </div>
+    </div>
 
-    // Listen for messages
-    socket.addEventListener("message", (event) => {
-      console.log("Message from server ", event.data);
-    });
-  </script>
+    <script>
+        let socket = new WebSocket("ws://localhost:8880/websocket");
+
+        // Listen for messages
+        socket.addEventListener("message", (event) => {
+            let message = event.data;
+            console.log("Message from server ", message);
+
+            let messageDiv = Templating.html(`<div class="message-entry">${message}</div>`).element;
+            document.getElementById("messagePanel").appendChild(messageDiv);
+        });
+
+        function sendRequest() {
+            let message = document.getElementById("messageInput").value;
+            console.log("Sending message: '" + message + "'");
+            socket.send(message);
+        }
+    </script>
 </body>
 </html>