QLoggingCategory可以控制打印输出类别和区域。方便在调试时，过滤掉不关心的打印信息。
QLoggingCategory Class
The QLoggingCategory class represents a category, or 'area' in the logging infrastructure. More...
Header: #include <QLoggingCategory>
qmake: QT += core
Since: Qt 5.2
https://blog.csdn.net/u010168781/article/details/84667524
