网页websocket一个经典的例子

最新推荐文章于 2025-10-27 22:58:39 发布

原创最新推荐文章于 2025-10-27 22:58:39 发布 · 590 阅读

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这篇文章详细介绍了如何使用Apache Tomcat的WebSocket功能，通过echo.xhtml示例，展示了如何在浏览器中实现客户端与服务器的连接，发送和接收消息。通过HTML、CSS和JavaScript，读者可以学习WebSocket的基本用法和事件处理。

这个例子来自于\tomcat\webapps\examples\websocket\echo.xhtml

源码如下：

<?xml version="1.0" encoding="UTF-8"?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
    <title>Apache Tomcat WebSocket Examples: Echo</title>
    <style type="text/css"><![CDATA[
        #connect-container {
            float: left;
            width: 400px
        }

        #connect-container div {
            padding: 5px;
        }

        #console-container {
            float: left;
            margin-left: 15px;
            width: 400px;
        }

        #console {
            border: 1px solid #CCCCCC;
            border-right-color: #999999;
            border-bottom-color: #999999;
            height: 170px;
            overflow-y: scroll;
            padding: 5px;
            width: 100%;
        }

        #console p {
            padding: 0;
            margin: 0;
        }
    ]]></style>
    <script type="application/javascript"><![CDATA[
        var ws = null;

        function setConnected(connected) {
            document.getElementById('connect').disabled = connected;
            document.getElementById('disconnect').disabled = !connected;
            document.getElementById('echo').disabled = !connected;
        }

        function connect() {
            var target = document.getElementById('target').value;
            if (target == '') {
                alert('Please select server side connection implementation.');
                return;
            }
            if ('WebSocket' in window) {
                ws = new WebSocket(target);
            } else if ('MozWebSocket' in window) {
                ws = new MozWebSocket(target);
            } else {
                alert('WebSocket is not supported by this browser.');
                return;
            }
            ws.onopen = function () {
                setConnected(true);
                log('Info: WebSocket connection opened.');
            };
            ws.onmessage = function (event) {
                log('Received: ' + event.data);
            };
            ws.onclose = function (event) {
                setConnected(false);
                log('Info: WebSocket connection closed, Code: ' + event.code + (event.reason == "" ? "" : ", Reason: " + event.reason));
            };
        }

        function disconnect() {
            if (ws != null) {
                ws.close();
                ws = null;
            }
            setConnected(false);
        }

        function echo() {
            if (ws != null) {
                var message = document.getElementById('message').value;
                log('Sent: ' + message);
				var message_len = 'len: ' + message.length;
				log(message_len);
                ws.send(message);
            } else {
                alert('WebSocket connection not established, please connect.');
            }
        }

        function updateTarget(target) {
            if (window.location.protocol == 'http:') {
                document.getElementById('target').value = 'ws://' + window.location.host + target;
            } else {
                document.getElementById('target').value = 'wss://' + window.location.host + target;
            }
        }

        function log(message) {
            var console = document.getElementById('console');
            var p = document.createElement('p');
            p.style.wordWrap = 'break-word';
            p.appendChild(document.createTextNode(message));
            console.appendChild(p);
            while (console.childNodes.length > 25) {
                console.removeChild(console.firstChild);
            }
            console.scrollTop = console.scrollHeight;
        }


        document.addEventListener("DOMContentLoaded", function() {
            // Remove elements with "noscript" class - <noscript> is not allowed in XHTML
            var noscripts = document.getElementsByClassName("noscript");
            for (var i = 0; i < noscripts.length; i++) {
                noscripts[i].parentNode.removeChild(noscripts[i]);
            }
        }, false);
    ]]></script>
</head>
<body>
<div class="noscript"><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websockets rely on Javascript being enabled. Please enable
    Javascript and reload this page!</h2></div>
<div>
    <div id="connect-container">
        <div>
            <span>Connect to service implemented using:</span>
            <!-- echo example using new programmatic API on the server side -->
            <input id="radio1" type="radio" name="group1" value="/examples/websocket/echoProgrammatic"
                   onclick="updateTarget(this.value);"/> <label for="radio1">programmatic API</label>
            <!-- echo example using new annotation API on the server side -->
            <input id="radio2" type="radio" name="group1" value="/examples/websocket/echoAnnotation"
                   onclick="updateTarget(this.value);"/> <label for="radio2">annotation API</label>
        </div>
        <div>
            <input id="target" type="text" size="40" style="width: 350px"/>
        </div>
        <div>
            <button id="connect" onclick="connect();">Connect</button>
            <button id="disconnect" disabled="disabled" onclick="disconnect();">Disconnect</button>
        </div>
        <div>
            <textarea id="message" style="width: 350px">Here is a message!</textarea>
        </div>
        <div>
            <button id="echo" onclick="echo();" disabled="disabled">Echo message</button>
        </div>
    </div>
    <div id="console-container">
        <div id="console"/>
    </div>
</div>
</body>
</html>