运行 Paho 客户端 MQTT 的订阅者时未找到类异常

Question

我正在尝试使用 org.eclipse.paho.client.mqttv3-1.2.0 中的软件包实现 Pub-Sub.jar

在用户代码下方：

import org.eclipse.paho.client.mqttv3.MqttClient;

import org.eclipse.paho.client.mqttv3.MqttTopic;

import org.eclipse.paho.client.mqttv3.MqttCallback;

import org.eclipse.paho.client.mqttv3.MqttMessage;

import org.eclipse.paho.client.mqttv3.MqttException;

import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;

import java.net.*;

public class Subscriber {

  //public static final String BROKER_URL = "tcp://iot.eclipse.org:1883";

  public static final String BROKER_URL = "tcp://localhost:1883";

  private MqttClient client;

  String topic = "Demo Topic";

  public static void main(String[] args) {

    System.out.println("MQTT Broker: " + BROKER_URL);

    new Subscriber();

  }

  public Subscriber() {

    String clientId = getMacAddress() + "-sub";

    System.out.println("Client ID = " + clientId);

    try   {

      client = new MqttClient(BROKER_URL, clientId);

      client.connect();

      client.setCallback(new SubscribeCallback());

      client.subscribe(topic);

    } catch (MqttException e) {

      e.printStackTrace(); System.exit(1);

    }

  }

  public byte[] getMacAddress(){

    byte[] mac = new byte[6];

    try{

      InetAddress address = InetAddress.getLocalHost();

      NetworkInterface nwi = NetworkInterface.getByInetAddress(address);

      mac = nwi.getHardwareAddress();

      System.out.println(mac);

    } catch(Exception e) {

      System.out.println(e);

    }

    return mac;

  }

}

class SubscribeCallback implements MqttCallback {

  @Override

  public void connectionLost (Throwable cause) { }

  @Override

  public void messageArrived (String topic, MqttMessage message) {

    System.out.println("Message arrived. Topic: " + topic

    + " Message: " + message.toString());

    if ("I'm gone".equals(topic)) {

      System.out.println("Sensor gone!");

    }

  }

  @Override

  public void deliveryComplete (IMqttDeliveryToken token) { }

Answer 1

您还需要将当前目录添加到类路径中java -cp .:org.eclipse.paho.client.mqttv3-1.2.0.jar Subscriber如果在窗口上运行，则更改 for。:;