143 lines
4.7 KiB
Java
143 lines
4.7 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package websocket.chat;
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import java.io.IOException;
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import java.util.ArrayDeque;
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import java.util.Queue;
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import java.util.Set;
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import java.util.concurrent.CopyOnWriteArraySet;
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import java.util.concurrent.atomic.AtomicInteger;
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import jakarta.websocket.OnClose;
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import jakarta.websocket.OnError;
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import jakarta.websocket.OnMessage;
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import jakarta.websocket.OnOpen;
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import jakarta.websocket.Session;
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import jakarta.websocket.server.ServerEndpoint;
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import org.apache.juli.logging.Log;
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import org.apache.juli.logging.LogFactory;
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import util.HTMLFilter;
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@ServerEndpoint(value = "/websocket/chat")
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public class ChatAnnotation {
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private static final Log log = LogFactory.getLog(ChatAnnotation.class);
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private static final String GUEST_PREFIX = "Guest";
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private static final AtomicInteger connectionIds = new AtomicInteger(0);
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private static final Set<ChatAnnotation> connections = new CopyOnWriteArraySet<>();
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private final String nickname;
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private Session session;
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/*
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* The queue of messages that may build up while another message is being sent. The thread that sends a message is
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* responsible for clearing any queue that builds up while that message is being sent.
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*/
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private Queue<String> messageBacklog = new ArrayDeque<>();
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private boolean messageInProgress = false;
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public ChatAnnotation() {
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nickname = GUEST_PREFIX + connectionIds.getAndIncrement();
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}
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@OnOpen
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public void start(Session session) {
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this.session = session;
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connections.add(this);
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String message = String.format("* %s %s", nickname, "has joined.");
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broadcast(message);
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}
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@OnClose
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public void end() {
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connections.remove(this);
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String message = String.format("* %s %s", nickname, "has disconnected.");
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broadcast(message);
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}
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@OnMessage
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public void incoming(String message) {
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// Never trust the client
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String filteredMessage = String.format("%s: %s", nickname, HTMLFilter.filter(message.toString()));
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broadcast(filteredMessage);
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}
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@OnError
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public void onError(Throwable t) throws Throwable {
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log.error("Chat Error: " + t.toString(), t);
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}
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/*
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* synchronized blocks are limited to operations that are expected to be quick. More specifically, messages are not
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* sent from within a synchronized block.
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*/
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private void sendMessage(String msg) throws IOException {
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synchronized (this) {
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if (messageInProgress) {
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messageBacklog.add(msg);
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return;
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} else {
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messageInProgress = true;
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}
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}
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boolean queueHasMessagesToBeSent = true;
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String messageToSend = msg;
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do {
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session.getBasicRemote().sendText(messageToSend);
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synchronized (this) {
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messageToSend = messageBacklog.poll();
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if (messageToSend == null) {
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messageInProgress = false;
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queueHasMessagesToBeSent = false;
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}
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}
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} while (queueHasMessagesToBeSent);
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}
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private static void broadcast(String msg) {
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for (ChatAnnotation client : connections) {
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try {
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client.sendMessage(msg);
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} catch (IOException e) {
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log.debug("Chat Error: Failed to send message to client", e);
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if (connections.remove(client)) {
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try {
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client.session.close();
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} catch (IOException e1) {
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// Ignore
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}
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String message = String.format("* %s %s", client.nickname, "has been disconnected.");
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broadcast(message);
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}
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}
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}
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}
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}
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