Java Websocket ?? ???: ?????? ?? ?? ??? ??? ???? ??, ???? ?? ??? ?????.

? ??????? ???? ??? ?? ??? ??? ????? ?? ??? ?????. ?? HTTP ??????? ?????? ??? ??? ??? ??? ?? ??? ???? ?? ? ????. ?? ?? ?????? ?? ???? ?? ?? ????? ??? ???? ??? ?? ? ??? ??? ?????. . WebSocket? ??? ??? ???? ?? ??????.

WebSocket? HTML5? ??? ???????. ??? ??? ???? ????? ?? ??? ????. ?????? ??? ??? ???? ?? ??? ?? ???? ?? ? ????. ?? ?? ??? ??????? ?? ?? ????? ??? ? ????.

Java? ? ?????? ??? ?? ???? ??? Websocket? ?? ??? ? ?? ??? ?????. Java?? ???? ???? ??? ??? ????.

? ?? ??? Java? WebSocket API? ???? ????. Maven ?? ????? ?? Java EE 7 ?????? javax.websocket ???? ?? API? ???? ? ??? ??? ? ????.

??? Java EE 7? javax.websocket ???? ?? API? ???? Websocket? ???? ????.

1. ServerEndpoint ?? ???? ?????.

@WebSocket ??? ???? ???? ???? Java ??? ? ???? ??? ????. ? ??? ??? ? ????. WebSocket ????? URI? ???? ? ??? WebSocket ??? ??????.

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
 
@ServerEndpoint(value = "/websocket")
public class WebSocketExample {
     
    @OnOpen
    public void onOpen(){
        System.out.println("Connection opened");
    }
     
    @OnClose
    public void onClose(){
        System.out.println("Connection closed");
    }
     
    @OnMessage
    public void onMessage(String message){
        System.out.println("Message received: " + message);
    }
}

WebSocketExample ???? WebSocket ????? ??? ?????. ?? ???? @ServerEndpoint ??? Endpoint ???? ?? ???? ???? ??? URI? ??????.

@OnOpen, @OnMessage ? @OnClose ??? ??? ???? WebSocket ??? ??? ???? ???? ??? ?? ? ??? ???? ???? ? ?????.

?? ??? ???? onMessage ?? ???? ?? ?????. ?? WebSocket ?? ??? ?????? ??????.

2. ????? ?? ???

public class WebSocketClientExample extends Endpoint {
 
    public static CountDownLatch latch;
 
    @Override
    public void onOpen(final Session session, EndpointConfig config) {
        System.out.println("Connected");
 
        try {
            session.getBasicRemote().sendText("Hello");
        } catch (IOException ex) {
        }
    }
 
    @Override
    public void onError(final Session session, Throwable t) {
        t.printStackTrace();
    }
}

WebSocket ?????? WebSocket API? ??? ?? ???? javax.websocket.Endpoint? ??? ? ????.

CountDownLatch? ???? ?????? ??? ???? ??? ?????.

onOpen() ?? ????? ??? ???? ???? ?????.

??: ? ???? session.getBasicRemote().sendText(“Hello”) ???? ???? ???? ?????. WebSocket API?? ???? ??? ? ?? ??, ? session.getAsyncRemote().sendText("Hello");? ????. ???? getBasicRemote() ???? ???? ?? getAsyncRemote() ???? ?????? ????. . ?. ?????? ???? ??? ??? getAsyncRemote()? ??? ? ????.

3. ??? ??? ?? ? ?????? ??

??? ?????? ????? ??? ???? ???? ???? ?? ??? ?????. ??????? ???? ?? ?? ??????? WebSocket ??? ?? ????? ?? ???. ?? ?? ???? ?? ?? ??? ?? ???? ???? ?? ? ? ????.

import javax.websocket.*;
import java.net.URI;
import java.util.concurrent.CountDownLatch;
 
public class AppRunner {
 
    public static void main(String[] args) throws Exception {
        WebSocketContainer container = ContainerProvider.getWebSocketContainer();
 
        CountDownLatch latch = new CountDownLatch(1);
 
        container.connectToServer(new WebSocketExample(), new URI("ws://localhost:8080/websocket"));
 
        latch.await();
    }
}

? ??? ??? WebSocket ?????? ???? localhost:8080?? WebSocket ??? ??? ?????. CountDownLatch ??? ???? ? ?? ?? ??? ?? ???? ??? ?????.

???? ??? ? ? ????? ?? http://localhost:8080/websocket? ???? JavaScript ??? ?? JavaScript WebSocket ??? ?? WebSocket ?????? ???? ?? ?? ? ????.

??:

??? ??? ?? WebSocket? ???? ?? ?? HTTP ??? ??? ???? ??? ?? ? ??????. Java ????? WebSocket API? ???? Websocket? ??? ? ????. ? ????? WebSocket ?? ? ?????? Java ?? ????? ?? ?? ?? ??? ?????. ??? ????? ??? ??? ????.

? ??? Java Websocket ?? ???: ?????? ?? ?? ??? ??? ???? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!