msquitto在java中的应用，一个小Demo

消息发布者

package com.gaofei.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;
/**
 * 发布服务
 * @author gaofei
 *
 */
public class ServerMQTT {//服务端MQTT
	 //tcp://MQTT安装的服务器地址:MQTT定义的端口号
    public static final String HOST = "tcp://localhost:1883";
    //定义一个主题
    public static final String TOPIC = "pos_message_all";
    //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;  //定义MQTT发布者客户端对象
    private MqttTopic topic11;  //发布主题
    private String userName = "admin";  //非必须-用户名
    private String passWord = "123456";  //非必须-密码

    private MqttMessage message;//发布者发布的消息

	public ServerMQTT() throws MqttException {
		  // 初始化与服务器连接，Url/cliendId/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(); //连接服务器支持的选项设置
        options.setCleanSession(false);//每次会话完毕session保存
        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); //时间为 20*1.5s发送一次
        try {
            client.setCallback(new PushCallback());//处理发布的消息
            client.connect(options);  //客户端连接上

            topic11 = client.getTopic(TOPIC);  //获取主题
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
	   /**
     * 发布消息
     * @param topic
     * @param message
     * @throws MqttPersistenceException
     * @throws MqttException
     */
    public void publish(MqttTopic topic , MqttMessage message) throws MqttPersistenceException,
            MqttException {
        MqttDeliveryToken token = topic.publish(message); //发布消息
        token.waitForCompletion(); //等待完成
        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();//创建MQTT发布客户端对象
        server.message = new MqttMessage();  //创建Mqqt消息对象
        server.message.setQos(1);  //设置服务质量QOS:1保证消息至少能到达一次
        server.message.setRetained(true);
        server.message.setPayload("这是推送消息的内容".getBytes());
        server.publish(server.topic11 , server.message);
        System.out.println(server.message.isRetained() + "------ratained状态");
    }
}

消息订阅者

package com.gaofei.utils;

import java.util.concurrent.ScheduledExecutorService;

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;

/**
 * 订阅服务
 * 模拟一个客户端订阅服务
 * @author rao
 *
 */
public class ClientMQTT {
	  public static final String HOST = "tcp://localhost:1883";
	    public static final String TOPIC1 = "pos_message_all";
	    private static final String clientid = "client11";
	    private MqttClient client;
	    private MqttConnectOptions options;
	    private String userName = "admin";    //非必须
	    private String passWord = "123456";  //非必须
	    @SuppressWarnings("unused")
	    private ScheduledExecutorService scheduler;

	    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，设置为true表示每次连接到服务器都以新的身份连接
	            options.setCleanSession(false);
	            // 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(TOPIC1);
	            //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
	            //遗嘱
	            options.setWill(topic, "close".getBytes(), 2, true);
	            client.connect(options);
	            //订阅消息
	            int[] Qos  = {1};
	            String[] topic1 = {TOPIC1};
	            client.subscribe(topic1, Qos);  //订阅主题

	        } catch (Exception e) {
	            e.printStackTrace();
	        }
	    }

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

}

消息的处理

package com.gaofei.utils;

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

public class PushCallback implements MqttCallback {

	@Override
	public void connectionLost(Throwable arg0) {
		  // 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 token) {//消息发送完
		 System.out.println("deliveryComplete---------" + token.isComplete());

	}

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


	}

}