java使用websocket 无法连接

以下是使用Java实现WebSocket长连接的步骤：

1. 导入相关的库和类：

import javax.websocket.ClientEndpoint;
import javax.websocket.CloseReason;
import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.WebSocketContainer;
import javax.websocket.server.ServerEndpoint;
import java.net.URI;

2. 创建一个WebSocket客户端类，并使用`@ClientEndpoint`注解标记：

@ClientEndpoint
public class WebSocketClient {
    private Session session;

    @OnOpen
    public void onOpen(Session session) {
        this.session = session;
        System.out.println("Connected to server");
    }

    @OnMessage
    public void onMessage(String message) {
        System.out.println("Received message: " + message);
    }

    @OnClose
    public void onClose(Session session, CloseReason closeReason) {
        System.out.println("Connection closed: " + closeReason.getReasonPhrase());
    }

    @OnError
    public void onError(Session session, Throwable throwable) {
        System.out.println("Error: " + throwable.getMessage());
    }

    public void sendMessage(String message) {
        try {
            session.getBasicRemote().sendText(message);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

3. 创建一个WebSocket客户端实例，并连接到服务器：

public class Main {
    public static void main(String[] args) {
        WebSocketContainer container = ContainerProvider.getWebSocketContainer();
        String uri = "ws://localhost:8080/websocket"; // WebSocket服务器的地址
        try {
            Session session = container.connectToServer(WebSocketClient.class, URI.create(uri));
            session.getBasicRemote().sendText("Hello, server!"); // 发送消息给服务器
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

请确保WebSocket服务器的地址和端口号与实际情况相符，并且服务器已正确配置和运行。