关于#qt#的问题：MQTTv3自动应答

import org.eclipse.paho.client.mqttv3.IMqttClient;
import org.eclipse.paho.client.mqttv3.IMqttMessageListener;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;

public class MQTTAutoResponder {

    public static void main(String[] args) {
        String broker = "tcp://localhost:1883";
        String clientId = "AutoResponder";
        MemoryPersistence persistence = new MemoryPersistence();

        try {
            // 创建一个MqttClient实例
            IMqttClient client = new MqttClient(broker, clientId, persistence);

            // 设置连接选项
            MqttConnectOptions connOpts = new MqttConnectOptions();
            connOpts.setCleanSession(false);

            // 连接到服务器
            client.connect(connOpts);

            // 订阅消息
            String topic = "test/topic";
            int qos = 1;
            client.subscribe(topic, qos, new IMqttMessageListener() {
                public void messageArrived(String topic, MqttMessage message) throws MqttException {
                    // 收到消息后自动应答
                    String response = "Received message: " + new String(message.getPayload());
                    client.publish(topic, response.getBytes(), qos, false);
                }
            });

            // 等待接收消息
            Thread.sleep(5000);

            // 断开连接
            client.disconnect();
        } catch (MqttException me) {
            me.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}