java使用websocket

Java可以使用Java API for WebSocket（JSR 356）来实现WebSocket通信。下面是一个简单的示例：

首先，需要创建一个Endpoint类来处理WebSocket连接：

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;

@ServerEndpoint("/websocket")
public class MyEndpoint {

    @OnOpen
    public void onOpen(Session session) {
        System.out.println("WebSocket opened: " + session.getId());
    }

    @OnMessage
    public void onMessage(String message, Session session) throws IOException {
        System.out.println("Message received: " + message);
        session.getBasicRemote().sendText("Received: " + message);
    }

    @OnClose
    public void onClose(Session session) {
        System.out.println("WebSocket closed: " + session.getId());
    }

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

然后，在应用程序中启动WebSocket服务器：

import javax.websocket.server.ServerEndpointConfig;
import org.glassfish.tyrus.server.Server;

public class MyServer {

    public static void main(String[] args) {
        Server server = new Server("localhost", 8080, "/myapp", null, MyEndpoint.class);
        try {
            server.start();
            System.out.println("WebSocket server started");
            Thread.currentThread().join();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            server.stop();
        }
    }
}

现在，可以使用WebSocket客户端连接到服务器：

var ws = new WebSocket("ws://localhost:8080/myapp/websocket");
ws.onopen = function() {
  console.log("WebSocket opened");
  ws.send("Hello, server!");
};
ws.onmessage = function(event) {
  console.log("Message received: " + event.data);
};
ws.onclose = function() {
  console.log("WebSocket closed");
};