QFileDialog能遍历整个文件系统来选择一个或者多个文件或者目录

函数原型(F1或者Fn+F1查看帮助文档，有更详细的解释)
QString QFileDialog::getOpenFileName(QWidget *parent = nullptr,
const QString &caption = QString(),
const QString &dir = QString(),
const QString &filter = QString(),
QString *selectedFilter = nullptr,
QFileDialog::Options options = Options());
QStringList QFileDialog::getOpenFileNames(QWidget *parent = nullptr, const QString &caption = QString(), const QString &dir = QString(), const QString &filter = QString(), QString *selectedFilter = nullptr, QFileDialog::Options options = Options());
QString QFileDialog::getSaveFileName(QWidget *parent = nullptr, const QString &caption = QString(), const QString &dir = QString(), const QString &filter = QString(), QString *selectedFilter = nullptr, QFileDialog::Options options = Options());
//选择已经有的目录
QString dir = QFileDialog::getExistingDirectory(this, tr("Open Directory"),
"/home",
QFileDialog::ShowDirsOnly
| QFileDialog::DontResolveSymlinks);
void QFileDialog::setDirectory(const QString &directory);
//可选择远程网路文件
QUrl QFileDialog::getSaveFileUrl(QWidget *parent = nullptr,
const QString &caption = QString(),
const QUrl &dir = QUrl(),
const QString &filter = QString(),
QString *selectedFilter = nullptr,
QFileDialog::Options options = Options(),
const QStringList &supportedSchemes = QStringList());