public class MqttService {

    public void connectPublishAndWaitAck(
            MqttDto mqttConfig,
            String msg,
            String publishTopic,
            String subscribeTopic,
            int timeoutSeconds) {

        CountDownLatch latch = new CountDownLatch(1); // 用于等待回执
        MqttAsyncClient tmpClient = null;

        try {
            tmpClient = createClient(mqttConfig); ...