无法订阅 paho mqtt java

Question

我是 mqtt 新手。入门我尝试向 mosquitto broker 发布和订阅主题。我能够发布消息。但是我的订阅者没有收听主题，它会在没有 waiting/polling 消息的情况下开始和停止。

这是订阅者代码，

public class MqttSubscriber implements MqttCallback {
private static final String TOPIC = "iot/endpoint";

public static void main(String[] args) {
    new MqttSubscriber().listen();
}

public  void listen() {
    MqttClient client = null;
    try {
        client = MqttClientGenerator.generateSubscriberClient();
        client.connect();
        System.out.println("Fetching messages...");
        client.subscribe(TOPIC);
        client.setCallback(this);
        client.disconnect();
      } catch (MqttException e) {
        e.printStackTrace();
      } catch (Exception e) {
        e.printStackTrace();
    }
}

public void connectionLost(Throwable t) {
    t.printStackTrace();
}

public void deliveryComplete(IMqttDeliveryToken arg0) {

}

public void messageArrived(String topic, MqttMessage message) throws Exception {
    System.out.println("Message received from broker...");
    System.out.println("Received Message: -- ");
    System.out.println(message.getPayload().toString());
}
}

MqttClientGenerator :

public class MqttClientGenerator {
private static final String BROKER_URI = "tcp://localhost:1883";
private static final String CLIENT_ID = "pub";
private static final String SUBSCRIBER_ID = "sub";


private MqttClientGenerator () {}

public static MqttClient generatePublisherClient() throws MqttException{
    //adding timestamp to make client name unique every time
    return new MqttClient(BROKER_URI, CLIENT_ID+new Date().getTime());
}

public static MqttClient generateSubscriberClient() throws MqttException{
    //adding timestamp to make client name unique every time
    return new MqttClient(BROKER_URI, SUBSCRIBER_ID+new Date().getTime());
}
}

我在这里错过了什么？

Answer 1

尝试删除断开客户端的那一行。

无法订阅 paho mqtt java

unable to subscribe paho mqtt java

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mqtt

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