Qt启动C++线程并在线程中修改界面

void Mystack::on_pushButton_9_clicked()
{
    QString str =  QFileDialog::getOpenFileName(this);
    if(str == "")
    {
        return;
    }
    std::thread t(&Mystack::getTrackData,this,str);
    t.detach();
    ui->label_147->setText("");
}

void Mystack::getTrackData(QString path)//path是excel的路径
{
    (void)CoInitialize(NULL);
    //读取excel所有数据
    QAxObject * excel = new QAxObject("Excel.Application");//选择excel软件
    excel->dynamicCall("Setvisible (bool Visible)","false");//不显示主窗体，后面打开excel的时候不显示
    excel->setProperty("DisplayAlerts",false);//不显示excel的警告信息，如果打开失败，不弹出框
    QAxObject *work_books = excel->querySubObject("WorkBooks");//选择work_books
    work_books->dynamicCall("Open(const QString&)", path);//设置excel存在路径
    QAxObject *work_book = excel->querySubObject("ActiveWorkBook");//选择work_book
    QAxObject *work_sheet = work_book->querySubObject("Sheets(int)",1); //Sheets也可换用WorkSheets，打开第一个sheet
    QAxObject *range_data = work_sheet->querySubObject("UsedRange");
    QVariant var = range_data->dynamicCall("Value");//将所有数据存在QVariant结构体里面
    //excel内存回收
    delete range_data;
    delete work_sheet;
    delete work_book;
    delete work_books;
    delete excel;
    //获取到所有数据
    allDataTvlist.clear();
    castVariant2ListListVariant(var,allDataTvlist);//自定义函数
    QList<QString> list;
    QString tmpStr;
    for(int i=1;i<allDataTvlist.size();i++)
    {
        tmpStr = allDataTvlist.at(i).at(0).toString();
        if(tmpStr=="批号")
        {
            continue;
        }
        if(NOT_FOUND==list.indexOf(tmpStr))
        {
            list.append(tmpStr);
        }
    }
    ui->comboBox->clear();//直接访问this的ui对象
    foreach (const QString &value, list)
    {
        ui->comboBox->addItem(value);
    }
    ui->comboBox->setCurrentIndex(0);
    ui->label_147->setText("请选择指定批号上传");
}