Java Websocket을 사용하여 인스턴트 메시징 기능을 구현하는 방법은 무엇입니까?

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;

@ServerEndpoint("/chat")
public class WebSocketServer {

    @OnOpen
    public void onOpen(Session session) {
        System.out.println("新连接已建立：" + session.getId());
    }

    @OnMessage
    public void onMessage(String message, Session session) {
        System.out.println("收到消息：" + message);
    }

    @OnClose
    public void onClose(Session session) {
        System.out.println("连接已关闭：" + session.getId());
    }

    @OnError
    public void onError(Throwable error) {
        System.out.println("发生错误：" + error.getMessage());
    }
}

import javax.websocket.*;
import java.io.IOException;
import java.net.URI;
import java.util.concurrent.CountDownLatch;

@ClientEndpoint
public class WebSocketClient {

    private static CountDownLatch latch;

    @OnOpen
    public void onOpen(Session session) {
        System.out.println("连接已建立：" + session.getId());
        latch.countDown();
    }

    @OnMessage
    public void onMessage(String message, Session session) {
        System.out.println("收到消息：" + message);
    }

    @OnClose
    public void onClose(Session session) {
        System.out.println("连接已关闭：" + session.getId());
    }

    @OnError
    public void onError(Throwable error) {
        System.out.println("发生错误：" + error.getMessage());
    }

    public static void main(String[] args) {
        latch = new CountDownLatch(1);

        WebSocketContainer container = ContainerProvider.getWebSocketContainer();
        try {
            Session session = container.connectToServer(WebSocketClient.class, URI.create("ws://localhost:8080/chat"));
            latch.await(); // 等待连接建立完成
            session.getBasicRemote().sendText("Hello, Server!"); // 发送消息给服务器

            session.close(); // 关闭连接
        } catch (IOException | DeploymentException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}