websocket实现java长连接,加代码

好的，下面是一个基于 Java 的 WebSocket 实现长连接的示例代码：

1. 首先，需要引入 Java WebSocket API 的依赖包，推荐使用 Tyrus，Maven 依赖如下：

<dependency>
    <groupId>org.glassfish.tyrus.bundles</groupId>
    <artifactId>tyrus-standalone-client</artifactId>
    <version>1.13.1</version>
</dependency>

2. 创建 WebSocket 客户端：

import javax.websocket.ClientEndpoint;
import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import java.io.IOException;
import java.net.URI;

@ClientEndpoint
public class WebSocketClient {

    private Session session;

    @OnOpen
    public void onOpen(Session session) {
        this.session = session;
    }

    @OnMessage
    public void onMessage(String message) {
        // 处理收到的消息
    }

    @OnClose
    public void onClose() {
        // 关闭连接
    }

    public void connect(String url) throws Exception {
        URI uri = new URI(url);
        WebSocketContainer container = ContainerProvider.getWebSocketContainer();
        container.connectToServer(this, uri);
    }

    public void sendMessage(String message) throws IOException {
        this.session.getBasicRemote().sendText(message);
    }

    public void close() throws IOException {
        this.session.close();
    }
}

3. 在主函数中使用 WebSocketClient：

public class Main {
    public static void main(String[] args) throws Exception {
        WebSocketClient client = new WebSocketClient();
        client.connect("ws://localhost:8080/ws");
        client.sendMessage("hello");
        // ...
        client.close();
    }
}

以上代码仅为示例，实际应用中需要根据实际需求进行适当的修改。