mqtt

一， 需求
Qt使用mqtt协议与服务端进行通信。

二，使用

1. 所有源码加入到工程里，我比较喜欢源码引用，这样在跨平台时，省去了路径的配置。
   https://github.com/emqx/qmqtt
2. 写一个单例，建立连接，并在连接成功时，订阅 主题。

#ifndef MQTTMANAGERT_H
#define MQTTMANAGERT_H

#include <iostream>
#include <mqtt/qmqtt.h>

class MQTTManager:public QObject
{
    Q_OBJECT
public:
    static MQTTManager* instance();

    void setInTemperature(QString newInTemperature);

private:
    ~MQTTManager();
    MQTTManager();

public slots:
    void doConnected();
    void onSubscribed(const QString& topic);
    void doDisconnected();
    void doDataReceived(QMQTT::Message message);

signals:
    void inTemperatureChanged();

private:
    //mqtt客户端
    QMQTT::Client *client;
    static MQTTManager *manager;

    //室内温度
    QString inTemperature;

};
#endif // MQTTMANAGERT_H

#include "mqttManagert.h"
MQTTManager* MQTTManager::manager=nullptr;
const QString HOST= "127.0.0.1";

//温度和湿度
const QString TOPIC_IN_TEMPERATURE_HUMIDITY ="qmqtt/in_temperature_humidity";

MQTTManager::MQTTManager(){
    client = new QMQTT::Client(QHostAddress(HOST),1883,this);
    connect(client,&QMQTT::Client::connected,this,&MQTTManager::doConnected);
    connect(client,&QMQTT::Client::disconnected,this,&MQTTManager::doDisconnected);
    connect(client,&QMQTT::Client::received,this,&MQTTManager::doDataReceived);
    connect(client, &QMQTT::Client::subscribed, this, &MQTTManager::onSubscribed);

    client->connectToHost();
}

MQTTManager::~MQTTManager(){
    client->disconnected();
}

MQTTManager* MQTTManager::instance(){
    if(!manager){
        manager = new MQTTManager();
    }
    return manager;
}

void MQTTManager::doConnected(){
    qDebug()<<"doConnected ok";
    client->subscribe(TOPIC_IN_TEMPERATURE_HUMIDITY);
}
void MQTTManager::onSubscribed(const QString& topic)
{
    qDebug() << "onSubscribed " << topic;
}

//解析数据
void MQTTManager::doDataReceived(QMQTT::Message message){
    QString mes = QString(message.id())+" "+QString(message.qos())+" "+message.topic()+" "+message.payload()+"\n";
    if(message.topic()==TOPIC_IN_TEMPERATURE_HUMIDITY){
        QStringList dataList = QString(message.payload()).split(",");
        if(dataList.size()==2){
            setInTemperature(dataList[0]);
        }
    }
}

void MQTTManager::doDisconnected(){
    qDebug()<<"doDisconnected ok";
}

void MQTTManager::setInTemperature(QString newInTemperature)
{
    if (inTemperature == newInTemperature)
        return;
    inTemperature = newInTemperature;
    emit inTemperatureChanged();
}

3. 发布主题，直接调用publish函数
   publish(const QMQTT::Message& message)