MQTT的学习之Mosquitto发布-订阅（2）

在《MQTT的学习之Mosquitto安装&使用（1）》一文末尾，我已经模拟了发布-订阅模式，只是那时在服务器直接模拟的，并不是java代码模拟的。下面贴出Java代码

1、首先引入依赖包：

<!-- mosquitto依赖 -->

        <dependency>

            <groupId>org.eclipse.paho</groupId>

            <artifactId>org.eclipse.paho.client.mqttv3</artifactId>

            <version>1.1.0</version>

        </dependency>

2、代码

ClientMQTT：

package org.mqtt.model;

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;

public class ClientMQTT {

   public static final String HOST = "tcp://192.168.238.133:1883";

   public static final String TOPIC = "sensor";

   private static final String clientid = "client11";

   private MqttClient client;

   private MqttConnectOptions options;

   private String userName = "admin";

   private String passWord = "password";

   private void start() {

       try {

           // 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 PushCallback());

           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  = {1};

           String[] topic1 = {TOPIC};

           client.subscribe(topic1, Qos);

       } catch (Exception e) {

           e.printStackTrace();

       }

   }

   public static void main(String[] args) throws MqttException {

       ClientMQTT client = new ClientMQTT();

       client.start();

   }

}

PushCallback：

package org.mqtt.model;

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

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

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

/**

 * 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 void messageArrived(MqttTopic topic, MqttMessage message) 接收已经预订的发布。

 *

 * public void connectionLost(Throwable cause) 在断开连接时调用。

 *

 * public void deliveryComplete(MqttDeliveryToken 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。

 *

 */

public class PushCallback implements MqttCallback {

    public void connectionLost(Throwable cause) {

        // 连接丢失后，一般在这里面进行重连

        System.out.println("连接断开，可以做重连");

    }

    @Override

    public void deliveryComplete(IMqttDeliveryToken arg0) {

        // publish后会执行到这里

        System.out.println("deliveryComplete---------" + arg0.isComplete());

    }

    @Override

    public void messageArrived(String arg0, MqttMessage arg1) throws Exception {

        System.out.println("接收消息主题:" + arg0);

        System.out.println("接收消息Qos:" + arg1.getQos());

        System.out.println("接收消息内容:" + new String(arg1.getPayload()));

    }

}

ServerMQTT：

package org.mqtt.model;

/**

 * Created by Administrator on 17-2-10.

 */

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;

public class ServerMQTT {

    //tcp://MQTT安装的服务器地址:MQTT定义的端口号

    public static final String HOST = "tcp://192.168.238.133:1883";

    //public static final String HOST = "tcp://10.10.10.201:1883";

    //定义一个主题

    public static final String TOPIC = "sensor";

    //定义MQTT的ID，可以在MQTT服务配置中指定

    private static final String clientid = "server11";

    private MqttClient client;

    private MqttTopic topic11;

    private String userName = "mosquitto";

    private String passWord = "";

    private MqttMessage message;

    /**

     * 构造函数

     * @throws MqttException

     */

    public ServerMQTT() 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();

    }

    /**

     *  用来连接服务器

     */

    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 PushCallback());

            client.connect(options);

            topic11 = client.getTopic(TOPIC);

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    /**

     *

     * @param topic

     * @param message

     * @throws MqttPersistenceException

     * @throws MqttException

     */

    public void publish(MqttTopic topic , MqttMessage message) throws MqttPersistenceException,

            MqttException {

        MqttDeliveryToken token = topic.publish(message);

        token.waitForCompletion();

        System.out.println("message is published completely! "

                + token.isComplete());

    }

    /**

     *  启动入口

     * @param args

     * @throws MqttException

     */

    public static void main(String[] args) throws MqttException {

        ServerMQTT server = new ServerMQTT();

        server.message = new MqttMessage();

        server.message.setQos(1);

        server.message.setRetained(true);

  //      server.message.setPayload("hello,topic11".getBytes());

        for(int i = 0; i < 1000000;i++){

             server.message.setPayload(("hello,see" + i).getBytes());

             server.publish(server.topic11 , server.message);

        }

       // server.publish(server.topic11 , server.message);

        System.out.println(server.message.isRetained() + "------ratained状态");

    }

}

经过测试：ClientMQTT可以实时接收到ServerMQTT发送的数据