解决Qt运行程序后，可用串口变化问题

1.Qt解决运行程序后，可用串口变化问题

2.设置定时器，定时刷新可用串口

//定义全局变量
QSerialPort *serialPort;
QTimer *timer;
QStringList portStringList; 
QString currentCOM = "";

//在主函数
timer = new QTimer; //定时扫描和更新串口
connect(timer,&QTimer::timeout,this,&Widget::showValidPort);
//实时更新端口号
timer->start(1000); 
//每1000ms定时检测串口状态
serialPort = new QSerialPort; 
//实例化串口对象
foreach(const QSerialPortInfo &info, 
        QSerialPortInfo::availablePorts()) //扫描可用串口
        portStringList += info.portName();
ui->com->addItems(portStringList);

//更新并检测串口函数实现
void showValidPort()
{
    QStringList newPortStringList;
    foreach(const QSerialPortInfo &info, QSerialPortInfo::availablePorts())
        newPortStringList += info.portName();
    if(newPortStringList.size() != portStringList.size())
    {
        portStringList = newPortStringList;
        ui->com->clear();
        ui->com->addItems(portStringList);
    }
    if(currentCOM != ui->com->currentText()) //串口突然断开连接了
    {
        currentCOM = ui->com->currentText();
        if("关闭" == ui->comSwitchBtn->text())
        {
            on_comSwitchBtn_clicked();
        }
    }
}


void on_comSwitchBtn_clicked()
{
    if("打开" == ui->comSwitchBtn->text())
    {
        currentCOM = ui->com->currentText();
        serialPort->setPortName(currentCOM); //获取串口号
        if(serialPort->open(QIODevice::ReadWrite)) //如果打开串口成功
        {
            //...
        }
    }
    else if("关闭" == ui->comSwitchBtn->text())
    {
        ui->comSwitchBtn->setText("打开");
        serialPort->close();
    }
}