gameclient | 2016-7月北京师范珠海学院10天实训讲座 主要讲解如下内容： 1、HTML5 CSS3 | Websocket library

Had the same issue. Downgrading to Android Studio 3.4 worked for me.

Check: https://www.reddit.com/r/libgdx/comments/fxrlsm/unable_to_run_two_or_more_application_in_parallel/

The answer to your question is quite simple: you need a way to identify who is who. And that is not socket.id because this only identifies sockets, not users, as you've already noticed.

So you need some authentication mechanism. Once a user authenticates you can reuse his true id (whether it is simply a name or an integer in a database is irrelevant). And then on the server side you keep a collection of pairs (true_id, socket_id). And whenever a message comes to that user, you broadcast it to all matched socket.io objects.

Edit: So here's the flow:

1. Client authenticates with the server, the server sends him his own true_id, which the client stores somewhere. The client may also store some session_id or maybe some other mechanism that will allow him fast reauthentication in case of disconnection (note: do not store credentials, its a security issue).
2. The server keeps track of (true_id, socket_id) pairs in the form of a double way, mutlivalue map (it's an implementation detail what kind of data structure should be used here, maybe two {} objects is enough). If a connection dies then (true_id, socket_id) entry is removed. Note that for a given true_id there still may be some other socket_id alive. And so it doesn't mean that the user disconnected. It only means that this particular channel is dead.
3. Users don't care about socket_id, they only care about true_id. What you emit is {target_id: true_id, ...} instead of {target_id: socket_id, ...} on the client side, when you want to send a direct message.
4. When the server receives such message with true_id inside, it retrieves all (true_id, socket_id) pairs and passes the message to all of these sockets (note: maybe you don't even need socket_id, you can simply store socket objects here). Although this is a business logic: do you allow multiple connections per user? I would. There are many edge cases here (like for example a client thinks that he disconnected, but the server thinks he is still connected, etc) and making this 100% correct is unfortunately impossible (due to the nature of networking). But with a bit of effort it is possible to make it work 99% of the time.
5. If a connection dies then it is your client's responsibility to automatically reconnect and reauthenticate. New socket_id for old true_id is generated on the server side.

Let me emphasize this again: clients don't care about socket_id at all. Because that doesn't identify them. This only identifies a channel. And only the server cares about this information.

The Server in your code isn't waiting for the incoming requests, it only serves a single incoming request and then kills itself due to the nature of the main method which starts it.

You need to have the server wait for the requests and do not die. Check the code snippet below to understand the logic.

Plus, always try to throw the exceptions if you can't do anything meaningful with it within the method it is caught in. In your code the main method of the server will anyway execute even if there is an exception caught in the start method

The console does not print anything, because the client sends the package is an empty array. The server is work right.

The error is your logic. If you press one button, then another (you have two active keys), then release one, you end up with a “none” state, then you have to wait for is initial press state before the repeat state kicks in

So, for example...

• Press Left (MOVE_LEFT)
• Press Right (MOVE_RIGHT)
• Release Left (MOVE_NONE)
• Delay between initial press of Right and repeat event occurs where nothing happens

A better idea is too setup a state where "none" is the absence of a "active" state and not a state.

For this, I use a Direction enum...

Please refer to this answer, it completely solves this question.

I solved it by skiping the tests when generationg the JAR:

Be sure to PrintWriter.flush() the messages you send after each write() in ClientWriterThread.java.

As a side note, in order to make the code clearer change your serverSocket variable name to clientSocket in the appropriate classes (GameClient.java and ClientWriterThread.java).

You can decalre a variable before the return statement: