目录
一、业务场景
硬件采集的数据传入EMQX平台(采用MQTT协议)，java通过代码连接MQTT服务器，进行采集数据接收、解析、业务处理、存储入库、数据展示。
MQTT 是基于 发布(Publish)/订阅(Subscribe) 模式来进行通信及数据交换的。
二、本文只讲解java连接MQTT服务器进行数据处理
1、新建springboot项目，pom文件中直接引入下面的mqtt依赖
<dependency>
<groupId>org.springframework.integration</groupId>
<artifactId>spring-integration-mqtt</artifactId>
</dependency>2、 编写MQTT工具类
package com.siborui.dc.mqtt;
import lombok.extern.slf4j.Slf4j;
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
/**
* MQTT工具类操作
*
* @author Mr.Qu
* @since v1.1.0 2020-01-10
*/
@Slf4j
@Component
public class MQTTConnect {
private String HOST = tcp://127.0.0.1:1883; //mqtt服务器的地址和端口号
private final String clientId = "DC" + (int) (Math.random() * 100000000);
private MqttClient mqttClient;
/**
* 客户端connect连接mqtt服务器
*
* @param userName 用户名
* @param passWord 密码
* @param mqttCallback 回调函数
**/
public void setMqttClient(String userName, String passWord, MqttCallback mqttCallback) throws MqttException {
MqttConnectOptions options = mqttConnectOptions(userName, passWord);
if (mqttCallback == null) {
mqttClient.setCallback(new Callback());
} else {
mqttClient.setCallback(mqttCallback);
}
mqttClient.connect(options);
}
/**
* MQTT连接参数设置
*/
private MqttConnectOptions mqttConnectOptions(String userName, String passWord) throws MqttException {
mqttClient = new MqttClient(HOST, clientId, new MemoryPersistence());
MqttConnectOptions options = new MqttConnectOptions();
options.setUserName(userName);
options.setPassword(passWord.toCharArray());
options.setConnectionTimeout(10);///默认：30
options.setAutomaticReconnect(true);//默认：false
options.setCleanSession(false);//默认：true
//options.setKeepAliveInterval(20);//默认：60
return options;
}
/**
* 关闭MQTT连接
*/
public void close() throws MqttException {
mqttClient.close();
mqttClient.disconnect();
}
/**
* 向某个主题发布消息 默认qos：1
*
* @param topic:发布的主题
* @param msg：发布的消息
*/
public void pub(String topic, String msg) throws MqttException {
MqttMessage mqttMessage = new MqttMessage();
//mqttMessage.setQos(2);
mqttMessage.setPayload(msg.getBytes());
MqttTopic mqttTopic = mqttClient.getTopic(topic);
MqttDeliveryToken token = mqttTopic.publish(mqttMessage);
token.waitForCompletion();
}
/**
* 向某个主题发布消息
*
* @param topic: 发布的主题
* @param msg: 发布的消息
* @param qos: 消息质量 Qos：0、1、2
*/
public void pub(String topic, String msg, int qos) throws MqttException {
MqttMessage mqttMessage = new MqttMessage();
mqttMessage.setQos(qos);
mqttMessage.setPayload(msg.getBytes());
MqttTopic mqttTopic = mqttClient.getTopic(topic);
MqttDeliveryToken token = mqttTopic.publish(mqttMessage);
token.waitForCompletion();
}
/**
* 订阅某一个主题 ，此方法默认的的Qos等级为：1
*
* @param topic 主题
*/
public void sub(String topic) throws MqttException {
mqttClient.subscribe(topic);
}
/**
* 订阅某一个主题，可携带Qos
*
* @param topic 所要订阅的主题
* @param qos 消息质量：0、1、2
*/
public void sub(String topic, int qos) throws MqttException {
mqttClient.subscribe(topic, qos);
}
/**
* main函数自己测试用
*/
public static void main(String[] args) throws MqttException {
MQTTConnect mqttConnect = new MQTTConnect();
mqttConnect.setMqttClient("admin", "public", new Callback());
mqttConnect.pub("com/dc/init", "Mr.Qu" + (int) (Math.random() * 100000000));
mqttConnect.sub("com/iot/init");
}
}
3、编写MQTT的回调函数
package com.siborui.dc.mqtt;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttMessage;
/**
* MQTT回调函数
*
* @author Mr.Qu
* @since 2020/1/9 16:26
*/
public class Callback implements MqttCallback {
/**
* MQTT 断开连接会执行此方法
*/
@Override
public void connectionLost(Throwable throwable) {
}
/**
* publish发布成功后会执行到这里
*/
@Override
public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
}
/**
* subscribe订阅后得到的消息会执行到这里
*/
@Override
public void messageArrived(String s, MqttMessage mqttMessage) throws Exception {
// TODO 此处可以将订阅得到的消息进行业务处理、数据存储
}
}
4、由于业务场景需要，在项目启动时，监听MQTT主题Topic，编写MQTT监听器
package com.siborui.dc.mqtt;
import lombok.extern.slf4j.Slf4j;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.stereotype.Component;
import com.siborui.dc.mqtt.Callback;
/**
* 项目启动 监听主题
*
* @author Mr.Qu
* @since 2020/1/10
*/
@Slf4j
@Component
public class MQTTListener implements ApplicationListener<ContextRefreshedEvent> {
private final MQTTConnect server;
@Autowired
public MQTTListener(MQTTConnect server) {
this.server = server;
}
@Override
public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
try {
server.setMqttClient("admin", "public", new Callback());
server.sub("com/iot/collection/");
} catch (MqttException e) {
log.error(e.getMessage(), e);
}
}
}
5、不明白之处请留言，感觉有用的 给个打赏
