如何使用paho mqtt java实现请求-响应模式？

<dependency>
    <groupId>org.eclipse.paho</groupId>
    <artifactId>org.eclipse.paho.client.mqttv3</artifactId>
    <version>1.2.5</version>
</dependency>

String broker = "tcp://mqtt.example.com:1883";
String clientId = "client1";
MqttClient client = new MqttClient(broker, clientId);

client.setCallback(new MqttCallback() {
    @Override
    public void connectionLost(Throwable cause) {
        // 处理连接断开的情况
    }

    @Override
    public void messageArrived(String topic, MqttMessage message) throws Exception {
        // 处理收到的消息
    }

    @Override
    public void deliveryComplete(IMqttDeliveryToken token) {
        // 处理消息发送完成的情况
    }
});

MqttConnectOptions options = new MqttConnectOptions();
options.setCleanSession(true);
client.connect(options);

String requestTopic = "request/topic";
int qos = 1;
client.subscribe(requestTopic, qos);

String requestPayload = "request payload";
MqttMessage requestMessage = new MqttMessage(requestPayload.getBytes());
String responseTopic = "response/topic";
client.publish(responseTopic, requestMessage);

@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
    if (topic.equals(responseTopic)) {
        String responsePayload = new String(message.getPayload());
        // 处理响应消息
    }
}