public abstract class Endpoint extends Object
onOpen
method, the programmatic endpoint gains access to the Session
object,
to which the developer may add MessageHandler
implementations in order to
intercept incoming websocket messages. Each instance
of a websocket endpoint is guaranteed not to be called by more than one thread
at a time per active connection.
If deployed as a client endpoint, it will be instantiated once for the single connection to the server.
When deployed as a server endpoint, the implementation uses the
ServerEndpointConfig.Configurator.getEndpointInstance(java.lang.Class<T>)
method to obtain the
endpoint instance it will use for each new client connection. If the developer uses
the default ServerEndpointConfig.Configurator
,
there will be precisely one
endpoint instance per active client connection. Consequently, in this typical
case, when implementing/overriding the methods of Endpoint, the developer is
guaranteed that there will be at most one thread calling each endpoint instance
at a time.
If the developer provides a custom ServerEndpointConfig.Configurator
which overrides the default policy for endpoint instance creation, for example,
using a single Endpoint instance for multiple client connections, the developer
may need to write code that can execute concurrently.
Here is an example of a simple endpoint that echoes any incoming text message back to the sender.
public class EchoServer extends Endpoint {
public void onOpen(Session session, EndpointConfig config) {
final RemoteEndpoint remote = session.getBasicRemote();
session.addMessageHandler(String.class, new MessageHandler.Whole<String>() {
public void onMessage(String text) {
try {
remote.sendString("Got your message (" + text + "). Thanks !");
} catch (IOException ioe) {
// handle send failure here
}
}
});
}
}
Constructor and Description |
---|
Endpoint() |
Modifier and Type | Method and Description |
---|---|
void |
onClose(Session session,
CloseReason closeReason)
This method is called immediately prior to the session with the remote
peer being closed.
|
void |
onError(Session session,
Throwable thr)
Developers may implement this method when the web socket session
creates some kind of error that is not modeled in the web socket protocol.
|
abstract void |
onOpen(Session session,
EndpointConfig config)
Developers must implement this method to be notified when a new conversation has
just begun.
|
public abstract void onOpen(Session session, EndpointConfig config)
session
- the session that has just been activated.config
- the configuration used to configure this endpoint.public void onClose(Session session, CloseReason closeReason)
session
- the session about to be closed.closeReason
- the reason the session was closed.public void onError(Session session, Throwable thr)
There are a number of categories of exception that this method is (currently) defined to handle:
SessionException
sDecodeException
ssession
- the session in use when the error occurs.thr
- the throwable representing the problem.Copyright © 1996-2013, Oracle and/or its affiliates. All Rights Reserved. Use is subject to license terms.