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Exemple de crear un servidor Websocket en Java7 i el client amb Javascript

http://www.mastertheboss.com/javaee/websockets/websocket-helloworld-example

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
 
  
@ServerEndpoint(value="/hello")
       
public class HelloWorldEndpoint {
    @OnMessage
    public String hello(String message) {
        System.out.println("Received : "+ message);
        return "Hello form the Server!";
    }
    @OnOpen
    public void myOnOpen(Session session) {
        System.out.println("WebSocket opened: " + session.getId());
    }
    @OnClose
    public void myOnClose(CloseReason reason) {
        System.out.println("Closing a due to " + reason.getReasonPhrase());
    }
    @OnError
    public void error(Throwable t) {      
         
    }
}

<html>
    <head>
        <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
    </head>
    <body>
        <meta charset="utf-8">
        <title>Your First WebSocket!</title>
        <script language="javascript" type="text/javascript">
             
            var wsUri = "ws://localhost:8080/javaee7-websocket-basic/hello";
             
            function init() {
                output = document.getElementById("output");
            }
            function send_message() {
                websocket = new WebSocket(wsUri);
                websocket.onopen = function(evt) {
                    onOpen(evt)
                };
                websocket.onmessage = function(evt) {
                    onMessage(evt)
                };
                websocket.onerror = function(evt) {
                    onError(evt)
                };
            }
            function onOpen(evt) {
                writeToScreen("Connected to Endpoint!");
                doSend(textID.value);
            }
            function onMessage(evt) {
                writeToScreen("Message Received: " + evt.data);
            }
            function onError(evt) {
                writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data);
            }
            function doSend(message) {
                writeToScreen("Message Sent: " + message);
                websocket.send(message);
                // You can close communication at any time
                //websocket.close();
            }
            function writeToScreen(message) {
                var pre = document.createElement("p");
                pre.style.wordWrap = "break-word";
                pre.innerHTML = message;
                  
                output.appendChild(pre);
            }
            window.addEventListener("load", init, false);
        </script>
        <h1 style="text-align: center;">Hello World WebSocket Client</h2>
        <br>
        <div style="text-align: center;">
            <form action="">
                <input onclick="send_message()" value="Send Message" type="button">
                <input id="textID" name="message" value="Hello WebSocket!" type="text"><br>
            </form>
        </div>
        <div id="output"></div>
</body>
</html>

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