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   <title>Using WebSocketListener</title><link rel="stylesheet" type="text/css" href="css/docbook.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><meta name="keywords" content="jetty, servlet, servlet-api, cometd, http, websocket, eclipse, maven, java, server, software"><link rel="home" href="index.html" title="Jetty"><link rel="up" href="websocket-jetty.html" title="Chapter&nbsp;27.&nbsp;Jetty Websocket API"><link rel="prev" href="jetty-websocket-api-annotations.html" title="Using WebSocket Annotations"><link rel="next" href="jetty-websocket-api-adapter.html" title="Using the WebSocketAdapter"><link xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" rel="shortcut icon" href="images/favicon.ico"><link rel="stylesheet" href="css/highlighter/foundation.css"><script src="js/highlight.pack.js"></script><script>
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            Version: 9.3.28.v20191105</span></td><td style="width: 50%"></td></tr></table><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Using WebSocketListener</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="jetty-websocket-api-annotations.html"><i class="fa fa-chevron-left" aria-hidden="true"></i> Previous</a>&nbsp;</td><th width="60%" align="center">Chapter&nbsp;27.&nbsp;Jetty Websocket API<br><a accesskey="p" href="index.html"><i class="fa fa-home" aria-hidden="true"></i> Home</a></th><td width="20%" align="right">&nbsp;<a accesskey="n" href="jetty-websocket-api-adapter.html">Next <i class="fa fa-chevron-right" aria-hidden="true"></i></a></td></tr></table><hr></div><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="jetty-callout"><h5 class="callout"><a href="http://www.webtide.com/">Contact the core Jetty developers at
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      </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="jetty-websocket-api-listener"></a>Using WebSocketListener</h2></div></div></div><p>The basic form of a WebSocket using the <a class="link" href="http://www.eclipse.org/jetty/javadoc/9.3.28.v20191105/org/eclipse/jetty/websocket/api/WebSocketListener.html" target="_top"><code class="literal">org.eclipse.jetty.websocket.api.WebSocketListener</code></a> for incoming events.</p><pre xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times"><code>//
//  ========================================================================
//  Copyright (c) 1995-2018 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package examples.echo;

import org.eclipse.jetty.websocket.api.Session;
import org.eclipse.jetty.websocket.api.WebSocketListener;

/**
 * Example EchoSocket using Listener.
 */
public class ListenerEchoSocket implements WebSocketListener
{
    private Session outbound;

    @Override
    public void onWebSocketBinary(byte[] payload, int offset, int len)
    {
        /* only interested in text messages */
    }

    @Override
    public void onWebSocketClose(int statusCode, String reason)
    {
        this.outbound = null;
    }

    @Override
    public void onWebSocketConnect(Session session)
    {
        this.outbound = session;
    }

    @Override
    public void onWebSocketError(Throwable cause)
    {
        cause.printStackTrace(System.err);
    }

    @Override
    public void onWebSocketText(String message)
    {
        if ((outbound != null) &amp;&amp; (outbound.isOpen()))
        {
            System.out.printf("Echoing back message [%s]%n",message);
            // echo the message back
            outbound.getRemote().sendString(message,null);
        }
    }
}</code></pre><p>This is by far the most basic and best performing (speed and memory wise) WebSocket implementation you can create.
If the listener is too much work for you, you can instead opt for the WebSocketAdapter</p></div><script type="text/javascript">
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