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Browse - Programming Tips - How can I do websockets with Jetty8?

Date: 2015jan24
Language: Java
Product: Jetty8

Q.  How can I do websockets with Jetty8?

A.  The java code:

package com.example; import javax.servlet.*; import javax.servlet.http.*; import org.eclipse.jetty.websocket.WebSocket; import org.eclipse.jetty.websocket.WebSocketServlet; import java.io.IOException; public class Echo extends WebSocketServlet { // Not necessary @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws javax.servlet.ServletException ,IOException { getServletContext().getNamedDispatcher("default").forward(request,response); } @Override public WebSocket doWebSocketConnect(HttpServletRequest request, String protocol) { return new EchoWebSocket(); } private class EchoWebSocket implements WebSocket, WebSocket.OnTextMessage { private Connection mConnection; void send(String txt) { try { mConnection.sendMessage(txt); } catch(IOException ex) { System.out.println(ex.toString()); } } @Override public void onOpen(Connection conn) { mConnection = conn; System.out.println("onOpen"); send("HELLO FROM OPEN"); } @Override public void onClose(int arg0, String arg1) { System.out.println("onClose"); } @Override public void onMessage(String txt) { System.out.println("got " + txt); send("HELLO, YOU SENT " + txt); } } }
web.xml:
<servlet> <servlet-name>Echo</servlet-name> <servlet-class>com.example.Echo</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>Echo</servlet-name> <url-pattern>/echo/*</url-pattern> </servlet-mapping>
The browser side:
<script> var ws; function go() { ws = new WebSocket("ws://localhost:8080/echo"); ws.onopen = onOpen; ws.onmessage = onMessage; ws.onclose = onClose; } function onOpen() { console.log('onOpen'); ws.send('from the js'); } function onClose() { console.log('onClose'); } function onMessage(m) { console.log('onMessage data=' + m.data); } </script> <button onClick="go()">Go</button>

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