I have a Websocket client, it sends request to Websocket server and then wait for response. I hope it can handle multiple calls (function getAppointments), but I am not sure what is wrong and it can only process one call at a time. Any suggestion? Thanks.

@Service
public class MyService {
    @Autowired 
    private websocketClient client;
    
    @Autowired
    private MessageHandler handler;

    public List<Appointment> getAppointments(Date startDate, Date endDate) {
        Long messageId = generateMessageId();
        Message message = new Message(messageId, startDate, endDate);
        client.sendMessage(message);
        
        Message response = handler.getResponseMessage(messageId);
        return extractAppointment(response);
    }
}

// Note, MessageHandler get called when Websocket client receives a message
@Service
public class MessageHandler {
        private Map<Long, Message> unprocessed = new HashMap<Long, Message>();

    @Override
    public void handleMessage(Message response ) {
        Long messageId = response.getMessageId();
        unprocessed.put(messageId, response);
        Thread.currentThread.interupt();
    }

    public Message getResponseMessage(long messageId) {
        CompletableFuture<Message> future = CompletableFuture.supplyAsync(new Supplier<Message>(){
            @Override
            public Message get() {
                Message response = unprocessed.get(messageId);
                while (response == null) {
                    try {
                        Thread.sleep(300);
                    } catch (InterruptedException e) {
                      ...
                    }
                }

                unprocessed.remove(messageId);
                return response;
            }
        });

        return future.get();
    }
}

CodePudding user response：