如何以编程方式在嵌入式tomcat中添加Websocket端点？

Question

I've been trying for weeks to get websockets working with embedded tomcat. I've tried emulating the examples in the tomcat unit tests to no avail. This is the first time I've tried to use websockets so I'm likely making a foolish mistake. Does anyone have any simple "Echo" examples for embedded tomcat websockets?

public void run() {

    if(!new File(consoleAppBase).isDirectory())
    {
         consoleAppBase = Paths.get("").toAbsolutePath().toString() + File.separatorChar + "wepapp";
    }

    tomcat = new Tomcat();

    tomcat.getService().removeConnector(tomcat.getConnector()); // remove default
    tomcat.getService().addConnector(createSslConnector(ConfigManager.getWeb_securePort())); // add secure option

    StandardServer server = (StandardServer) tomcat.getServer();
    AprLifecycleListener listener = new AprLifecycleListener();
    server.addLifecycleListener(listener);

    try {
        SecurityConstraint constraint = new SecurityConstraint();
        constraint.setDisplayName("SSL Redirect Constraint");
        constraint.setAuthConstraint(true);
        SecurityCollection collection = new SecurityCollection();
        collection.addPattern("/*");
        constraint.addAuthRole("administrator");
        constraint.addCollection(collection);

        //create the console webapp.
        consoleContext = tomcat.addWebapp(consoleContextPath, consoleAppBase);
        consoleContext.addConstraint(constraint);

        //this allows that little login popup for the console webapp.
        LoginConfig loginConfig = new LoginConfig();
        loginConfig.setAuthMethod("BASIC");
        consoleContext.setLoginConfig(loginConfig);
        consoleContext.addSecurityRole("administrator");

        //this creates a valid user.
        tomcat.addUser(ConfigManager.getWeb_username(), Encryptor.decrypt(ConfigManager.getWeb_passwordEncrypted()));
        tomcat.addRole("admin", "administrator");

    } catch (ServletException e) {
        LogMaster.getWebServerLogger().error("Error launching Web Application. Stopping Web Server.");
        LogMaster.getErrorLogger().error("Error launching Web Application. Stopping Web Server.", e);
        return;
    }

    addServlets(); // this is where I usually call a convenience method to add servlets

    // How can I add websocket endpoints instead?

}

Answer 1

I was using WebSocket in such way:

import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
//...

@ServerEndpoint("/move")
public class TestWebSocketEndPoint {//@OnMessage 
public void onMessage(Session session, String message) {}
private static final Queue<Session> QUEUE = new ConcurrentLinkedQueue<Session>();

@OnOpen
public void open(Session session) {
    QUEUE.add(session);
}

@OnError
public void error(Session session, Throwable t) {
    StaticLogger.log(TestWebSocketEndPoint.class, t);
    QUEUE.remove(session);
}

@OnClose
public void closedConnection(Session session) {
    QUEUE.remove(session);
}

public static void sendToAll(String message) throws IOException {
    ArrayList<Session> closedSessions = new ArrayList<Session>();
    for (Session session : QUEUE) {
        if (!session.isOpen()) {
            closedSessions.add(session);
        } else {
            session.getBasicRemote().sendText(message);
        }
    }
    QUEUE.removeAll(closedSessions);
}
}

And JS call:

var webSocket;
webSocket = new WebSocket("ws://localhost:8585/test/move");
webSocket.onmessage = function () {
    alert('test');
}

Java call:

  TestWebSocketEndPoint.sendToAll(result);

Answer 2

For programmatic (non-annotated) endpoints, you have to provide a class that implements Endpoint to act as the server end, and then either:

1. Deploy a class that implements ServerApplicationConfig in your WAR file, that supplies EndpointConfig information about some or all of the non-annotated Endpoint instances that were found in the WAR file, or
2. Call ServerContainer.addEndpoint() during the deployment phase of your webapp.

See the Java™ API for WebSocket, JSR 356.

Answer 3

As far as I know, configuring a websocket is the same as configuring a servlet (or a servlet filter). In web.xml you must include <async-supported>true</async-supported> .

I assume there's a similar flag in the java config.