Java线程通过MQTT循环发送消息

要在Java线程中使用MQTT循环发送消息，你需要使用MQTT客户端库并提供连接到MQTT代理的详细信息。以下是一个简单的Java代码示例，它使用Eclipse Paho MQTT客户端库来发送消息：

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

public class MqttPublisher implements MqttCallback {

    private MqttClient mqttClient;
    private String brokerUrl;
    private String clientId;
    private MemoryPersistence persistence;

    public MqttPublisher(String brokerUrl, String clientId) {
        this.brokerUrl = brokerUrl;
        this.clientId = clientId;
        this.persistence = new MemoryPersistence();
    }

    public void connect() throws MqttException {
        mqttClient = new MqttClient(brokerUrl, clientId, persistence);
        mqttClient.setCallback(this);
        MqttConnectOptions connOpts = new MqttConnectOptions();
        connOpts.setCleanSession(true);
        mqttClient.connect(connOpts);
    }

    public void publish(String topic, String content) throws MqttException {
        MqttMessage message = new MqttMessage(content.getBytes());
        message.setQos(0);
        mqttClient.publish(topic, message);
    }

    public void connectionLost(Throwable throwable) {
        System.out.println("Connection lost: " + throwable.getMessage());
    }

    public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
        // Process incoming message
    }

    public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
        // Delivery complete
    }
}

然后，在你的主类中，你可以创建一个MqttPublisher对象并调用connect()方法进行连接。在连接成功后，你可以调用publish()方法来发送消息：

public static void main(String[] args) throws MqttException {
    MqttPublisher publisher = new MqttPublisher("tcp://localhost:1883", "publisher");
    publisher.connect();
    for (int i = 0; i < 10; i++) {
        publisher.publish("my/topic", "Message " + i);
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

这将在循环中发送10条消息到主题“my/topic”。你可以根据需要更改主题和消息内容。