java mqtt对接门禁把手demo

以下是一个Java Mqtt对接门禁把手的Demo：

import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;

public class DoorControl {

    private static final String BROKER_URL = "tcp://localhost:1883";
    private static final String TOPIC = "door-control";
    private static final String CLIENT_ID = "DoorControl";

    public static void main(String[] args) {
        try {
            MqttClient client = new MqttClient(BROKER_URL, CLIENT_ID, new MemoryPersistence());
            MqttConnectOptions options = new MqttConnectOptions();
            options.setCleanSession(true);
            client.connect(options);

            client.subscribe(TOPIC);

            client.setCallback(new MqttCallback() {
                @Override
                public void connectionLost(Throwable cause) {
                    System.out.println("Connection lost: " + cause.getMessage());
                }

                @Override
                public void messageArrived(String topic, MqttMessage message) throws Exception {
                    String payload = new String(message.getPayload());
                    if (payload.equals("open")) {
                        System.out.println("Opening door...");
                        // 在这里编写开门的逻辑
                    } else if (payload.equals("close")) {
                        System.out.println("Closing door...");
                        // 在这里编写关门的逻辑
                    } else {
                        System.out.println("Unknown command: " + payload);
                    }
                }

                @Override
                public void deliveryComplete(IMqttDeliveryToken token) {
                    // 不需要实现
                }
            });

            System.out.println("Door control started.");
        } catch (MqttException e) {
            System.out.println("Error: " + e.getMessage());
        }
    }
}

这个Demo使用了Eclipse Paho Mqtt库来连接Mqtt服务器并订阅门禁控制的主题。当收到开门或关门的命令时，它会打印相应的消息并执行相应的开门或关门的逻辑。你只需要在对应的地方编写你的门禁控制逻辑即可。