Jetty 8.1.9.v20130131 Web Socket issues

问题

I do have a strange problem with jetty 8 websockets. I found several tutorials that pretty much show the same code, yet I get this error when I try to open the websocket from a local html page:

2013-02-05 13:14:03.467:INFO:oejs.Server:jetty-8.1.9.v20130131
2013-02-05 13:14:03.770:INFO:oejs.AbstractConnector:Started SelectChannelConnector@0.0.0.0:8080
2013-02-05 13:14:18.002:WARN:oejs.ServletHandler:/echo
java.lang.NullPointerException
    at org.eclipse.jetty.websocket.WebSocketFactory.upgrade(WebSocketFactory.java:236)
    at org.eclipse.jetty.websocket.WebSocketFactory.acceptWebSocket(WebSocketFactory.java:382)
    at org.eclipse.jetty.websocket.WebSocketServlet.service(WebSocketServlet.java:104)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:669)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:457)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)

Here is the Socket servlet:

public class ExampleWebSocketServlet extends WebSocketServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see WebSocketServlet#WebSocketServlet()
     */
    public ExampleWebSocketServlet() {
        super();
    }



protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        out.println("OK");
        out.close();
        System.out.println("OK");
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        getServletContext().getNamedDispatcher("default").forward(request, response);
    }


    public WebSocket doWebSocketConnect(HttpServletRequest request, String protocol) {
        return new EchoWebSocket();
    }
}

and the WebSocket (for a simple Echo)

public class EchoWebSocket implements WebSocket.OnTextMessage {

    private Connection con;

    @Override
    public void onClose(int closeCode, String message) {

    }

    @Override
    public void onOpen(Connection con) {
        this.con = con;

        try {
            con.sendMessage("Server received Web Socket upgrade ...");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onMessage(String msg) {
        System.out.println("Received: "+msg);

        try {
            con.sendMessage(msg);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } //send it back

    }
}

My html page works fine with other websocket test servers, e.g. websocket.org

What could be wrong? I am on Eclipse, created a dynamic web project and use the jetty webapp run configuration. Also, when jetty starts up i can see that

/Users/sven.haiges/dev/jetty/jetty-distribution-8.1.9.v20130131/lib/jetty-websocket-8.1.9.v20130131.jar

is on the classpath.

Any help appreciated,thx!

回答1:

I had a same problem with Run Jetty Run plugin. finally found solution. go to run configuration

select your project name under jetty webapp on left panel
select jetty version 8.1 on right side under Jetty Tab

Apply / Run that's all

回答2:

Try using the Jetty 8.1.8 version. Today, I had an issue creating a simple servlet via @WebServlet annotation. The jetty server did not respond and I could not figure out why. But when I suddenly changed back to version 8.1.8, everything worked fine. Maybe it's a similar problem.

来源：https://stackoverflow.com/questions/14707694/jetty-8-1-9-v20130131-web-socket-issues

标签

websocket

jetty