基于：Eclipse paho 的MQTT Java客户端实现数据的发送和接收

MQTT(MQ Telemetry Transport)是IBM开发的一种网络应用层的协议

使用场景：

1、不可靠、网络带宽小的网络

2、运行的设备CPU、内存非常有限

特点：

1、基于发布/订阅模型的协议

2、他是二进制协议，二进制的特点就是紧凑、占用空间小。他的协议头只有2个字节

3、提供了三种消息可能性保障：最多一次 0、最少一次 1、只有一次 2

maven依赖

<dependency>
    <groupId>org.eclipse.pahogroupId>
    <artifactId>org.eclipse.paho.client.mqttv3artifactId>
    <version>1.1.1version>
dependency>

发送消息示例

import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
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.MqttMessage;
import org.eclipse.paho.client.mqttv3.MqttPersistenceException;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;

/**
 * 发送数据到mqtt服务器
 * @author：涂有
 * @date 2017年8月16日 下午11:15:22
 */
public class PubMsg {
    private static int qos = 2; //只有一次
    private static String broker = "tcp://10.100.124.206:1883";
    private static String userName = "tuyou";
    private static String passWord = "tuyou";


    private static MqttClient connect(String clientId,String userName,
            String password) throws MqttException {
        MemoryPersistence persistence = new MemoryPersistence();
        MqttConnectOptions connOpts = new MqttConnectOptions();
        connOpts.setCleanSession(true);
        connOpts.setUserName(userName);
        connOpts.setPassword(password.toCharArray());
        connOpts.setConnectionTimeout(10);
        connOpts.setKeepAliveInterval(20);
//      String[] uris = {"tcp://10.100.124.206:1883","tcp://10.100.124.207:1883"};
//      connOpts.setServerURIs(uris);  //起到负载均衡和高可用的作用
        MqttClient mqttClient = new MqttClient(broker, clientId, persistence);
        mqttClient.setCallback(new PushCallback("test"));
        mqttClient.connect(connOpts);
        return mqttClient;
    }

    private static void pub(MqttClient sampleClient, String msg,String topic)
            throws MqttPersistenceException, MqttException {
        MqttMessage message = new MqttMessage("ertwersdfas".getBytes());
        message.setQos(qos);
        message.setRetained(false);
        sampleClient.publish(topic, message);
    }

    private static void publish(String str,String clientId,String topic) throws MqttException{
        MqttClient mqttClient = connect(clientId,userName,passWord);

        if (mqttClient != null) {
            pub(mqttClient, str, topic);
            System.out.println("pub-->" + str);
        }

        if (mqttClient != null) {
            mqttClient.disconnect();
        }
    }

    public static void main(String[] args) throws MqttException {
        publish("message content","client-id-0","$share/edge/server/public/a");
    }
}

class PushCallback implements MqttCallback {
    private String threadId;
    public PushCallback(String threadId){
        this.threadId = threadId;
    }

    public void connectionLost(Throwable cause) {

    }

    public void deliveryComplete(IMqttDeliveryToken token) {
//       System.out.println("deliveryComplete---------" + token.isComplete());
    }

    public void messageArrived(String topic, MqttMessage message) throws Exception {
        String msg = new String(message.getPayload());
        System.out.println(threadId + " " + msg);
    }
}

消费消息示例

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.persist.MemoryPersistence;

public class SubMsg {

//   private static String topic = "$share/testgroup/wyptest1";
//   private static String topic = "$queue/wyptest1";
//   private static String topic = "wyptest1";
     private static int qos = 2;
     private static String broker = "tcp://10.100.124.207:1883";
     private static String userName = "tuyou";
     private static String passWord = "tuyou";


     private static MqttClient connect(String clientId) throws MqttException{
         MemoryPersistence persistence = new MemoryPersistence();
         MqttConnectOptions connOpts = new MqttConnectOptions();
//       String[] uris = {"tcp://10.100.124.206:1883","tcp://10.100.124.206:1883"};
         connOpts.setCleanSession(false);
         connOpts.setUserName(userName);
         connOpts.setPassword(passWord.toCharArray());
         connOpts.setConnectionTimeout(10);
         connOpts.setKeepAliveInterval(20);
//         connOpts.setServerURIs(uris);
//         connOpts.setWill(topic, "close".getBytes(), 2, true);
         MqttClient mqttClient = new MqttClient(broker, clientId, persistence);
         mqttClient.connect(connOpts);
         return mqttClient;
     }

     public static void sub(MqttClient mqttClient,String topic) throws MqttException{
         int[] Qos  = {qos};
         String[] topics = {topic};
         mqttClient.subscribe(topics, Qos);
     }


    private static void runsub(String clientId, String topic) throws MqttException{
        MqttClient mqttClient = connect(clientId);
        if(mqttClient != null){
            sub(mqttClient,topic);
        }
    }
    public static void main(String[] args) throws MqttException{

        runsub("client-id-1", "$share/testgroupa/edge/server/private/+");
    }
}