Mqtt协议 服务器交互

1.服务器发送消息

package demo1;

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;
/**
* Title:Server 这是发送消息的服务端
* Description: 服务器向多个客户端推送主题，即不同客户端可向服务器订阅相同主题
* @author rao
*/
/**
* @author xiaoxia
* @ClassName ServerMQTT
* @param
* 2019年10月9日下午5:59:27
* @version
*/
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://39.105.195.90:1883";
//定义一个主题
public static final String TOPIC = "test";
//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 = "admin"; //非必须
private String passWord = "public"; //非必须

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); //保证消息能到达一次
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");
}
}

2.客户端接收消息

package demo1;

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;

import com.sun.prism.Texture;

/**
* 模拟一个客户端接收消息
* @author rao
*
*/
/**
* @author xiaoxia
* @ClassName ClientMQTT
* @param
* 2019年10月9日下午5:59:11
* @version
*/
public class ClientMQTT {

public static final String HOST = "tcp://39.105.195.90:1883";
public static final String TOPIC1 = "/sdgj/EP34";
private static final String clientid = "client11";
private MqttClient client;
private MqttConnectOptions options;
private String userName = "test"; //非必须
private String passWord = "password"; //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(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(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);

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

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

2.1客户端依赖文件

package demo1;

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。
*
*/
/**
* @author xiaoxia
* @ClassName PushCallback
* @param
* 2019年10月9日下午5:58:42
* @version
*/
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");
// ClientMQTT client = new ClientMQTT();
// client.start();
}

public void deliveryComplete(IMqttDeliveryToken token) {
System.out.println("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
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()));
}
}