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