Java mqtt订阅与发布信息

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智能创新者 2024-09-04 15:55:01

文章标签 Java mqtt订阅与发布信息 eclipse 客户端服务器 文章分类 Java 后端开发

添加依赖:

<dependency>
　　<groupId>org.eclipse.paho</groupId>
　　<artifactId>org.eclipse.paho.client.mqttv3</artifactId>
　　<version>1.1.1</version>
</dependency>

MQ发布者:

package com.ra.car.utils;

import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.MqttPersistenceException;
import org.eclipse.paho.client.mqttv3.MqttTopic;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * MQ发布者
 * 
 * @author lanhao
 * 
 */
public class MQTTPubMsg {
    protected static final Logger logger = LoggerFactory
            .getLogger(MQTTPubMsg.class);
    public static final String HOST = "tcp://10.74.20.43:1883";
    public static final String TOPIC = "toclient/124";
//    public static final String TOPIC125 = "toclient/125";
    private static final String clientid = "server";
    private MqttClient client;
    private MqttTopic topic;
//    private MqttTopic topic125;
    private String userName = "root";
    private String passWord = "Passw0rd";
    private MqttMessage message;

    public MQTTPubMsg() throws MqttException {
        // MemoryPersistence设置clientid的保存形式，默认为以内存保存
        client = new MqttClient(HOST, clientid, new MemoryPersistence());
        connect();
    }

    private void connect() {
        MqttConnectOptions options = new MqttConnectOptions();
        options.setCleanSession(false);
        options.setUserName(userName);
        options.setPassword(passWord.toCharArray());
        // 设置超时时间
        options.setConnectionTimeout(10);
        // 设置会话心跳时间
        options.setKeepAliveInterval(20);
        try {
            client.setCallback(new MQTTPushCallback());
            client.connect(options);
            topic = client.getTopic(TOPIC);
//            topic125 = client.getTopic(TOPIC125);
        } catch (Exception e) {
            logger.error("MQ发布者connect异常......",e);
        }
    }

    public void publish(MqttTopic topic, MqttMessage message)
            throws MqttPersistenceException, MqttException {
        MqttDeliveryToken token = topic.publish(message);
        token.waitForCompletion();
        logger.info("message is published completely! "
                + token.isComplete());
    }

    public static void main(String[] args) throws MqttException {
        MQTTPubMsg server = new MQTTPubMsg();
        String s="这是第一条消息";
        server.message = new MqttMessage();
        server.message.setQos(2);
        server.message.setRetained(true);
        server.message.setPayload(s.getBytes());
        server.publish(server.topic, server.message);
        
        try {
            Thread.sleep(20000);
        } catch (InterruptedException e) {
        }
        for (int i = 0; i < 500; i++) {
            String str = "这是后续循环发送的消息" + i;
            server.message = new MqttMessage();
            server.message.setQos(2);
            server.message.setRetained(true);
            server.message.setPayload(str.getBytes());
            server.publish(server.topic, server.message);

            // 给另外一个topic发送消息
            
             * server.message = new MqttMessage(); server.message.setQos(2);
             * server.message.setRetained(true);
             * server.message.setPayload("给客户端125推送的信息".getBytes());
             * server.publish(server.topic125, server.message);
             

            logger.info(server.message.isRetained() + "------ratained状态");
        }
    }

}

MQ订阅者:

package com.ra.car.utils;

import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttTopic;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * MQ订阅者
 * 
 * @author lanhao
 * 
 */
public class MQTTSubMsg {
    protected static final Logger logger = LoggerFactory
            .getLogger(MQTTSubMsg.class);
    public static final String HOST = "tcp://10.74.20.43:1883";
    public static final String TOPIC = "toclient/124";
    private static final String clientid = "client124";
    private MqttClient client;
    private MqttConnectOptions options;
    private String userName = "root";
    private String passWord = "Passw0rd";

    public void start() {
        try {
            logger.info("SubMsg----->start");
            // host为主机名，clientid即连接MQTT的客户端ID，一般以唯一标识符表示，MemoryPersistence设置clientid的保存形式，默认为以内存保存
            client = new MqttClient(HOST, clientid, new MemoryPersistence());
            // MQTT的连接设置
            options = new MqttConnectOptions();
            // 设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录，这里设置为true表示每次连接到服务器都以新的身份连接
            options.setCleanSession(true);
            // 设置连接的用户名
            options.setUserName(userName);
            // 设置连接的密码
            options.setPassword(passWord.toCharArray());
            // 设置超时时间 单位为秒
            options.setConnectionTimeout(10);
            // 设置会话心跳时间 单位为秒 服务器会每隔1.5*20秒的时间向客户端发送个消息判断客户端是否在线，但这个方法并没有重连的机制
            options.setKeepAliveInterval(20);
            // 设置回调
            client.setCallback(new MQTTPushCallback());
            MqttTopic topic = client.getTopic(TOPIC);
            // setWill方法，如果项目中需要知道客户端是否掉线可以调用该方法。设置最终端口的通知消息
            options.setWill(topic, "close".getBytes(), 2, true);
            client.connect(options);
            // 订阅消息
            int[] Qos = { 2 };
            String[] topic1 = { TOPIC };
            client.subscribe(topic1, Qos);
        } catch (Exception e) {
            logger.error("MQ订阅者异常",e);
        }
    }

    public static void main(String[] args) throws MqttException {
        MQTTSubMsg client = new MQTTSubMsg();
        client.start();
    }

}

回调类:

package com.ra.car.utils;

import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 发布消息的回调类
 * 
 * 必须实现MqttCallback的接口并实现对应的相关接口方法CallBack 类将实现 MqttCallBack。
 * 每个客户机标识都需要一个回调实例。在此示例中，构造函数传递客户机标识以另存为实例数据。 在回调中，将它用来标识已经启动了该回调的哪个实例。
 * 必须在回调类中实现三个方法
 */
public class MQTTPushCallback implements MqttCallback{
    protected static final Logger logger = LoggerFactory
            .getLogger(MQTTPushCallback.class);
    public void connectionLost(Throwable cause) {
        // 在断开连接时调用,连接丢失后,一般在这里面进行重连.
        logger.info("连接断开，可以做重连");
    }

    public void deliveryComplete(IMqttDeliveryToken token) {
        //接收到已经发布的 QoS 1 或 QoS 2 消息的传递令牌时调用. 由 MqttClient.connect 激活此回调.
        logger.info("deliveryComplete---------" + token.isComplete());
    }

    public void messageArrived(String topic, MqttMessage message)
            throws Exception {
        // subscribe后得到的消息会执行到这里面
        logger.info("接收消息主题 : " + topic);
        logger.info("接收消息Qos : " + message.getQos());
        logger.info("接收消息内容 : " + new String(message.getPayload()));
    }
}

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