Qt中獲取系統(tǒng)圖標、類型是通過QFileIconProvider來實現(xiàn)的，具體如下：

一、Qt獲取系統(tǒng)文件圖標1、獲取文件夾圖標QFileIconProvider icon_provider;QIcon icon = icon_provider.icon(QFileIconProvider::Folder);2、獲取指定文件圖標QFileInfo file_info(name);
QFileIconProvider icon_provider;
QIcon icon = icon_provider.icon(file_info);二、Windows編程中獲取系統(tǒng)圖標、類型：QIcon Setting::getFileIcon(QString file_name)
{QIcon file_icon = QIcon(":/icon/file");if(!file_name.isEmpty()){//獲取后綴std::string str = "file";int index = file_name.lastIndexOf(".");if(index >= 0){QString suffix = file_name.mid(index); //將QString轉(zhuǎn)化為std::stringstr = suffix.toUtf8().constData(); //std::string((const char *)path.toLocal8Bit())  path.toLatin1().data();}LPCSTR name = str.c_str();SHFILEINFOA info;if(SHGetFileInfoA(name,FILE_ATTRIBUTE_NORMAL,&info,sizeof(info),SHGFI_SYSICONINDEX | SHGFI_ICON | SHGFI_USEFILEATTRIBUTES)){HICON icon = info.hIcon;file_icon = QIcon(QPixmap::fromWinHICON(icon));}}return file_icon;
}QString Setting::getFileType(QString file_name)
{QString file_type = QString("file");if(!file_name.isEmpty()){//獲取后綴std::string str = "file";int index = file_name.lastIndexOf(".");if(index >= 0){QString suffix = file_name.mid(index); //將QString轉(zhuǎn)化為std::stringstr = suffix.toUtf8().constData();}LPCSTR name = str.c_str();SHFILEINFOA info;if(SHGetFileInfoA(name,FILE_ATTRIBUTE_NORMAL,&info,sizeof(info),SHGFI_TYPENAME | SHGFI_USEFILEATTRIBUTES)){std::string type = info.szTypeName;file_type = type.c_str();}}return file_type;
}QIcon Setting::getFolderIcon()
{QIcon folder_icon = QIcon(":/icon/folder");//將QString轉(zhuǎn)化為std::stringstd::string str = "folder";LPCSTR name = str.c_str();SHFILEINFOA info;if(SHGetFileInfoA(name,FILE_ATTRIBUTE_DIRECTORY,&info,sizeof(info),SHGFI_SYSICONINDEX | SHGFI_ICON | SHGFI_USEFILEATTRIBUTES)){HICON h_icon = info.hIcon;folder_icon = QIcon(QPixmap::fromWinHICON(h_icon)); }return folder_icon;
}QString Setting::getFolderType()
{QString folder_type = QString("folder");std::string str = "folder";LPCSTR name = str.c_str();SHFILEINFOA info;if(SHGetFileInfoA(name,FILE_ATTRIBUTE_DIRECTORY,&info,sizeof(info),SHGFI_TYPENAME | SHGFI_USEFILEATTRIBUTES)){std::string type = info.szTypeName;folder_type = type.c_str();}return folder_type;
}

兩種方式最大的區(qū)別是什么呢？參考：filesystems - Qt 4.8 - QFileIconProvider, Getting icon for non-existent file (based on extension) - Stack Overflow?諸如所言，Qt所提供的獲取圖標的方法是本地已存在的文件，如果要通過擴展名來獲取圖標則需要自己來虛擬構造本地文件，而在數(shù)據(jù)量較大的情況下往往會影響性能。這（通過擴展名獲取圖標、類型）可以通過Windows API來實現(xiàn)，即方法二。

Qt5開始QPixmap::fromWinHICON(HICON)已經(jīng)消失得無影無蹤，且獲取圖標、后綴的方法仍針對本地已存在的文件，那么，只能另尋出路，此節(jié)講述如何通過擴展名來創(chuàng)建臨時文件，并獲取對應的圖標、類型。

步驟：

通過擴展名extension（.***）構造臨時文件QTemporaryFile

通過QFileIconProvider獲取對應的圖標、類型

刪除臨時文件

獲取圖標QIcon FileIcon::fileExtensionIcon(const QString & extension) const 
{
QFileIconProvider icon_provider;
QIcon icon;
QTemporaryFile tmp_file(QDir::tempPath() + QDir::separator() +
QCoreApplication::applicationName() + "_XXXXXX" + extension);
tmp_file.setAutoRemove(false);if(tmp_file.open()) 
{
QString file_name = tmp_file.fileName();
tmp_file.write(QByteArray());
tmp_file.close();icon = icon_provider.icon(QFileInfo(file_name));
tmp_file.remove();
} 
else 
{
qCritical()<<QString("failed to write temporary file %1") .arg(tmp_file.fileName());
}return icon;
}

獲取類型QString FileIcon::fileExtensionType(const QString & extension) const 
{
QFileIconProvider icon_provider;
QString type;
QTemporaryFile tmp_file(QDir::tempPath() + QDir::separator() +
QCoreApplication::applicationName() + "_XXXXXX" + extension);
tmp_file.setAutoRemove(false);if(tmp_file.open()) 
{
QString file_name = tmp_file.fileName();
tmp_file.write(QByteArray());
tmp_file.close();type = icon_provider.type(QFileInfo(file_name));tmp_file.remove();
} 
else 
{
qCritical()<<QString("failed to write temporary file %1") .arg(tmp_file.fileName());
}return type; 
}

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