QFileInfo 类

The QFileInfo class provides an OS-independent API to retrieve information about file system entries. 更多...

头：	#include <QFileInfo>
CMake:	find_package(Qt6 REQUIRED COMPONENTS Core) target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake:	QT += core

所有成员列表，包括继承成员
QFileInfo is part of 输入/输出和网络 and 隐式共享类 .

注意： 此类的所有函数可重入 .

公共函数

	QFileInfo ()
	QFileInfo (const QString & path )
	QFileInfo (const QFileDevice & file )
	QFileInfo (const QDir & dir , const QString & path )
`(从 6.0 起)`	QFileInfo (const std::filesystem::path & file )
`(从 6.0 起)`	QFileInfo (const QDir & dir , const std::filesystem::path & path )
	QFileInfo (const QFileInfo & fileinfo )
	~QFileInfo ()
QDir	absoluteDir () const
QString	absoluteFilePath () const
QString	absolutePath () const
QString	baseName () const
QDateTime	birthTime () const
`(从 6.6 起)` QDateTime	birthTime (const QTimeZone & tz ) const
QString	bundleName () const
bool	caching () const
QString	canonicalFilePath () const
QString	canonicalPath () const
QString	completeBaseName () const
QString	completeSuffix () const
QDir	dir () const
bool	exists () const
QString	fileName () const
QString	filePath () const
QDateTime	fileTime (QFileDevice::FileTime time ) const
`(从 6.6 起)` QDateTime	fileTime (QFileDevice::FileTime time , const QTimeZone & tz ) const
`(从 6.0 起)` std::filesystem::path	filesystemAbsoluteFilePath () const
`(从 6.0 起)` std::filesystem::path	filesystemAbsolutePath () const
`(从 6.0 起)` std::filesystem::path	filesystemCanonicalFilePath () const
`(从 6.0 起)` std::filesystem::path	filesystemCanonicalPath () const
`(从 6.0 起)` std::filesystem::path	filesystemFilePath () const
`(从 6.2 起)` std::filesystem::path	filesystemJunctionTarget () const
`(从 6.0 起)` std::filesystem::path	filesystemPath () const
`(从 6.6 起)` std::filesystem::path	filesystemReadSymLink () const
`(从 6.0 起)` std::filesystem::path	filesystemSymLinkTarget () const
QString	group () const
uint	groupId () const
bool	isAbsolute () const
`(从 6.4 起)` bool	isAlias () const
bool	isBundle () const
bool	isDir () const
bool	isExecutable () const
bool	isFile () const
bool	isHidden () const
bool	isJunction () const
bool	isNativePath () const
bool	isReadable () const
bool	isRelative () const
bool	isRoot () const
bool	isShortcut () const
bool	isSymLink () const
bool	isSymbolicLink () const
bool	isWritable () const
`(从 6.2 起)` QString	junctionTarget () const
QDateTime	lastModified () const
`(从 6.6 起)` QDateTime	lastModified (const QTimeZone & tz ) const
QDateTime	lastRead () const
`(从 6.6 起)` QDateTime	lastRead (const QTimeZone & tz ) const
bool	makeAbsolute ()
QDateTime	metadataChangeTime () const
`(从 6.6 起)` QDateTime	metadataChangeTime (const QTimeZone & tz ) const
QString	owner () const
uint	ownerId () const
QString	path () const
bool	permission (QFileDevice::Permissions permissions ) const
QFileDevice::Permissions	permissions () const
`(从 6.6 起)` QString	readSymLink () const
void	refresh ()
void	setCaching (bool enable )
void	setFile (const QString & path )
void	setFile (const QFileDevice & file )
void	setFile (const QDir & dir , const QString & path )
`(从 6.0 起)` void	setFile (const std::filesystem::path & path )
qint64	size () const
`(从 6.0 起)` void	stat ()
QString	suffix () const
void	swap (QFileInfo & other )
QString	symLinkTarget () const
bool	operator!= (const QFileInfo & fileinfo ) const
QFileInfo &	operator= (const QFileInfo & fileinfo )
QFileInfo &	operator= (QFileInfo && other )
bool	operator== (const QFileInfo & fileinfo ) const

静态公共成员

bool	exists (const QString & path )

QFileInfoList

宏

(从 6.0 起) QT_IMPLICIT_QFILEINFO_CONSTRUCTION

详细描述

QFileInfo provides information about a file system entry, such as its name, path, access rights and whether it is a regular file, directory or symbolic link. The entry's size and last modified/read times are also available. QFileInfo can also be used to obtain information about a Qt resource .

A QFileInfo can point to a file system entry with either an absolute or a relative path:

On Unix, absolute paths begin with the directory separator '/' . On Windows, absolute paths begin with a drive specification (for example, D:/ ).
Relative paths begin with a directory name or a regular file name and specify a file system entry's path relative to the current working directory.

An example of an absolute path is the string "/tmp/quartz" . A relative path may look like "src/fatlib" . You can use the function isRelative () to check whether a QFileInfo is using a relative or an absolute path. You can call the function makeAbsolute () to convert a relative QFileInfo's path to an absolute path.

注意： Paths starting with a colon ( : ) are always considered absolute, as they denote a QResource .

The file system entry path that the QFileInfo works on is set in the constructor or later with setFile ()。使用 exists () to see if the entry actually exists and size () to get its size.

The file system entry's type is obtained with isFile (), isDir ()，和 isSymLink ()。 symLinkTarget () function provides the absolute path of the target the symlink points to.

The path elements of the file system entry can be extracted with path () 和 fileName ()。 fileName ()'s parts can be extracted with baseName (), suffix ()，或 completeSuffix (). QFileInfo objects referring to directories created by Qt classes will not have a trailing directory separator '/' . If you wish to use trailing separators in your own file info objects, just append one to the entry's path given to the constructors or setFile ().

Date and time related information are returned by birthTime (), fileTime (), lastModified (), lastRead ()，和 metadataChangeTime (). Information about access permissions can be obtained with isReadable (), isWritable ()，和 isExecutable (). Ownership information can be obtained with owner (), ownerId (), group ()，和 groupId (). You can also examine permissions and ownership in a single statement using the permission () 函数。

Symbolic Links and Shortcuts

On Unix (including macOS and iOS), the property getter functions in this class return the properties such as times and size of the target, not the symlink, because Unix handles symlinks transparently. Opening a symlink using QFile effectively opens the link's target. For example:

#ifdef Q_OS_UNIX
QFileInfo info1("/home/bob/bin/untabify");
info1.isSymLink();          // returns true
info1.absoluteFilePath();   // returns "/home/bob/bin/untabify"
info1.size();               // returns 56201
info1.symLinkTarget();      // returns "/opt/pretty++/bin/untabify"
QFileInfo info2(info1.symLinkTarget());
info2.isSymLink();          // returns false
info2.absoluteFilePath();   // returns "/opt/pretty++/bin/untabify"
info2.size();               // returns 56201
#endif

On Windows, shortcuts ( .lnk files) are currently treated as symlinks. As on Unix systems, the property getters return the size of the target, not the .lnk file itself. This behavior is deprecated and will likely be removed in a future version of Qt, after which .lnk files will be treated as regular files.

#ifdef Q_OS_WIN
QFileInfo info1("C:\\Users\\Bob\\untabify.lnk");
info1.isSymLink();          // returns true
info1.absoluteFilePath();   // returns "C:/Users/Bob/untabify.lnk"
info1.size();               // returns 63942
info1.symLinkTarget();      // returns "C:/Pretty++/untabify"
QFileInfo info2(info1.symLinkTarget());
info2.isSymLink();          // returns false
info2.absoluteFilePath();   // returns "C:/Pretty++/untabify"
info2.size();               // returns 63942
#endif

NTFS permissions

在 NTFS 文件系统，默认情况下，出于性能原因禁用所有权和权限校验。要启用它，包括以下行：

extern Q_CORE_EXPORT int qt_ntfs_permission_lookup;

然后打开和关闭权限校验，通过递增和递减 qt_ntfs_permission_lookup by 1.

qt_ntfs_permission_lookup++; // turn checking on
qt_ntfs_permission_lookup--; // turn it off again

注意： 由于这是非原子全局变量，它才安全递增或递减 qt_ntfs_permission_lookup 在除主线程外的任何线程已启动前，或在除主线程外的每个线程已结束后。

注意： 从 Qt 6.6 起，变量 qt_ntfs_permission_lookup 被弃用。请使用下列替代。

管理权限校验的安全且轻松方式是使用 RAII 类 QNtfsPermissionCheckGuard .

void complexFunction()
{
    QNtfsPermissionCheckGuard permissionGuard;  // check is enabled
    // do complex things here that need permission check enabled
}   // as the guard goes out of scope the check is disabled

若需要更细粒度控制，取而代之，采用下列函数管理权限是可能的：

qAreNtfsPermissionChecksEnabled();   // check status
qEnableNtfsPermissionChecks();       // turn checking on
qDisableNtfsPermissionChecks();      // turn it off again

性能注意事项

Some of QFileInfo's functions have to query the file system, but for performance reasons, some functions only operate on the path string. For example: To return the absolute path of a relative entry's path, absolutePath () 必须查询文件系统。 path () 函数，不管怎样，可以直接处理文件名，因此速度更快。

QFileInfo also caches information about the file system entry it refers to. Because the file system can be changed by other users or programs, or even by other parts of the same program, there is a function that refreshes the information stored in QFileInfo, namely refresh (). To switch off a QFileInfo's caching (that is, force it to query the underlying file system every time you request information from it), call setCaching (false).

Fetching information from the file system is typically done by calling (possibly) expensive system functions, so QFileInfo (depending on the implementation) might not fetch all the information from the file system at construction. To make sure that all information is read from the file system immediately, use the stat () member function.

birthTime (), fileTime (), lastModified (), lastRead ()，和 metadataChangeTime () return times in local time by default. Since native file system API typically uses UTC, this requires a conversion. If you don't actually need the local time, you can avoid this by requesting the time in QTimeZone::UTC 直接。

平台具体问题

在 Android，会应用一些局限性当处理内容 URI (统一资源标识符) :

可能需要提示用户的访问权限透过 QFileDialog 实现 Android 本机文件拾取器 .
目标是遵循作用域存储指导方针 (譬如：使用 App 特定目录，而不是其它公共外部目录)。更多信息，另请参阅存储最佳实践 .
Due to the design of Qt APIs (e.g. QFile ), it's not possible to fully integrate the latter APIs with Android's MediaStore API。

另请参阅 QDir and QFile .

成员函数文档编制

QFileInfo:: QFileInfo ()

Constructs an empty QFileInfo object that doesn't refer to any file system entry.

另请参阅 setFile ().

`[explicit]` QFileInfo:: QFileInfo (const QString & path )

Constructs a QFileInfo that gives information about a file system entry located at path that can be absolute or relative.

若 path is relative, the QFileInfo will also have a relative path.

另请参阅 setFile (), isRelative (), QDir::setCurrent ()，和 QDir::isRelativePath ().

`[explicit]` QFileInfo:: QFileInfo (const QFileDevice & file )

Constructs a new QFileInfo that gives information about file file .

若 file has a relative path, the QFileInfo will also have a relative path.

另请参阅 isRelative ().

`[explicit]` QFileInfo:: QFileInfo (const QDir & dir , const QString & path )

Constructs a new QFileInfo that gives information about the given file system entry path that is relative to the directory dir .

若 dir has a relative path, the QFileInfo will also have a relative path.

若 path is absolute, then the directory specified by dir will be disregarded.

另请参阅 isRelative ().

`[since 6.0]` QFileInfo:: QFileInfo (const std::filesystem::path & file )

Constructs a new QFileInfo that gives information about the given file .

该函数在 Qt 6.0 引入。

另请参阅 setFile (), isRelative (), QDir::setCurrent ()，和 QDir::isRelativePath ().

`[since 6.0]` QFileInfo:: QFileInfo (const QDir & dir , const std::filesystem::path & path )

Constructs a new QFileInfo that gives information about the file system entry at path that is relative to the directory dir .

若 dir has a relative path, the QFileInfo will also have a relative path.

若 path is absolute, then the directory specified by dir will be disregarded.

该函数在 Qt 6.0 引入。

QFileInfo:: QFileInfo (const QFileInfo & fileinfo )

Constructs a new QFileInfo that is a copy of the given fileinfo .

`[noexcept]` QFileInfo:: ~QFileInfo ()

销毁 QFileInfo and frees its resources.

QDir QFileInfo:: absoluteDir () const

返回 QDir object representing the absolute path of the parent directory of the file system entry that this QFileInfo refers to.

// Given a current working directory of "/home/user/Documents/memos/"
QFileInfo info1(u"relativeFile"_s);
qDebug() << info1.absolutePath(); // "/home/user/Documents/memos/"
qDebug() << info1.baseName(); // "relativeFile"
qDebug() << info1.absoluteDir(); // QDir(u"/home/user/Documents/memos"_s)
qDebug() << info1.absoluteDir().path(); // "/home/user/Documents/memos"
// A QFileInfo on a dir
QFileInfo info2(u"/home/user/Documents/memos"_s);
qDebug() << info2.absolutePath(); // "/home/user/Documents"
qDebug() << info2.baseName(); // "memos"
qDebug() << info2.absoluteDir(); // QDir(u"/home/user/Documents"_s)
qDebug() << info2.absoluteDir().path(); // "/home/user/Documents"

另请参阅 dir (), filePath (), fileName ()，和 isRelative ().

QString QFileInfo:: absoluteFilePath () const

Returns the absolute full path to the file system entry this QFileInfo refers to, including the entry's name.

On Unix, absolute paths begin with the directory separator '/' . On Windows, absolute paths begin with a drive specification (for example, D:/ ).

On Windows, the paths of network shares that are not mapped to a drive letter begin with //sharename/ .

QFileInfo will uppercase drive letters. Note that QDir does not do this. The code snippet below shows this.

    QFileInfo fi("c:/temp/foo"); => fi.absoluteFilePath() => "C:/temp/foo"

此函数返回如同 filePath (), unless isRelative () is true. In contrast to canonicalFilePath (), symbolic links or redundant "." or ".." elements are not necessarily removed.

警告： 若 filePath () is empty the behavior of this function is undefined.

另请参阅 filePath (), canonicalFilePath ()，和 isRelative ().

QString QFileInfo:: absolutePath () const

Returns the absolute path of the file system entry this QFileInfo refers to, excluding the entry's name.

On Unix, absolute paths begin with the directory separator '/' . On Windows, absolute paths begin with a drive specification (for example, D:/ ).

On Windows, the paths of network shares that are not mapped to a drive letter begin with //sharename/ .

In contrast to canonicalPath () symbolic links or redundant "." or ".." elements are not necessarily removed.

警告： 若 filePath () is empty the behavior of this function is undefined.

另请参阅 absoluteFilePath (), path (), canonicalPath (), fileName ()，和 isRelative ().

QString QFileInfo:: baseName () const

Returns the base name of the file without the path.

The base name consists of all characters in the file up to (but not including) the first '.' character.

范例：

QFileInfo fi("/tmp/archive.tar.gz");
QString base = fi.baseName();  // base = "archive"

The base name of a file is computed equally on all platforms, independent of file naming conventions (e.g., ".bashrc" on Unix has an empty base name, and the suffix is "bashrc").

另请参阅 fileName (), suffix (), completeSuffix ()，和 completeBaseName ().

QDateTime QFileInfo:: birthTime () const

Returns the date and time when the file was created (born), in local time.

If the file birth time is not available, this function returns an invalid QDateTime .

If the file is a symlink, this function returns information about the target, not the symlink.

This function overloads QFileInfo::birthTime(const QTimeZone &tz), and returns the same as birthTime(QTimeZone::LocalTime) .

另请参阅 lastModified (), lastRead (), metadataChangeTime ()，和 fileTime ().

`[since 6.6]` QDateTime QFileInfo:: birthTime (const QTimeZone & tz ) const

Returns the date and time when the file was created (born).

The returned time is in the time zone specified by tz . For example, you can use QTimeZone::LocalTime or QTimeZone::UTC to get the time in the Local time zone or UTC, respectively. Since native file system API typically uses UTC, using QTimeZone::UTC is often faster, as it does not require any conversions.

If the file birth time is not available, this function returns an invalid QDateTime .

If the file is a symlink, this function returns information about the target, not the symlink.

该函数在 Qt 6.6 引入。

另请参阅 lastModified (const QTimeZone &), lastRead (const QTimeZone &), metadataChangeTime (const QTimeZone &), and fileTime (QFileDevice::FileTime, const QTimeZone &).

QString QFileInfo:: bundleName () const

Returns the name of the bundle.

On macOS and iOS this returns the proper localized name for a bundle if the path isBundle (). On all other platforms an empty QString 被返回。

范例：

QFileInfo fi("/Applications/Safari.app");
QString bundle = fi.bundleName();                // name = "Safari"

另请参阅 isBundle (), filePath (), baseName ()，和 suffix ().

bool QFileInfo:: caching () const

返回 true if caching is enabled; otherwise returns false .

另请参阅 setCaching () 和 refresh ().

QString QFileInfo:: canonicalFilePath () const

Returns the file system entry's canonical path, including the entry's name, that is, an absolute path without symbolic links or redundant '.' or '..' 元素。

If the entry does not exist, canonicalFilePath() returns an empty string.

另请参阅 filePath (), absoluteFilePath ()，和 dir ().

QString QFileInfo:: canonicalPath () const

Returns the file system entry's canonical path (excluding the entry's name), i.e. an absolute path without symbolic links or redundant "." or ".." elements.

If the entry does not exist, this method returns an empty string.

另请参阅 path () 和 absolutePath ().

QString QFileInfo:: completeBaseName () const

Returns the complete base name of the file without the path.

The complete base name consists of all characters in the file up to (but not including) the last '.' character.

范例：

QFileInfo fi("/tmp/archive.tar.gz");
QString base = fi.completeBaseName();  // base = "archive.tar"

另请参阅 fileName (), suffix (), completeSuffix ()，和 baseName ().

QString QFileInfo:: completeSuffix () const

Returns the complete suffix (extension) of the file.

The complete suffix consists of all characters in the file after (but not including) the first '.'.

范例：

QFileInfo fi("/tmp/archive.tar.gz");
QString ext = fi.completeSuffix();  // ext = "tar.gz"

另请参阅 fileName (), suffix (), baseName ()，和 completeBaseName ().

QDir QFileInfo:: dir () const

返回 QDir object representing the path of the parent directory of the file system entry that this QFileInfo refers to.

注意： The QDir returned always corresponds to the object's parent directory, even if the QFileInfo represents a directory.

For each of the following, dir() returns the QDir "~/examples/191697" .

    QFileInfo fileInfo1("~/examples/191697/.");
    QFileInfo fileInfo2("~/examples/191697/..");
    QFileInfo fileInfo3("~/examples/191697/main.cpp");

For each of the following, dir() returns the QDir "." .

    QFileInfo fileInfo4(".");
    QFileInfo fileInfo5("..");
    QFileInfo fileInfo6("main.cpp");

另请参阅 absolutePath (), filePath (), fileName (), isRelative ()，和 absoluteDir ().

bool QFileInfo:: exists () const

返回 true if the file system entry this QFileInfo refers to exists; otherwise returns false .

注意： If the entry is a symlink that points to a non-existing target, this method returns false .

`[static]` bool QFileInfo:: exists (const QString & path )

返回 true if the file system entry path 存在；否则返回 false .

注意： 若 path is a symlink that points to a non-existing target, this method returns false .

注意： 使用此函数会更快相比使用 QFileInfo(path).exists() 对于文件系统访问。

QString QFileInfo:: fileName () const

Returns the name of the file system entry this QFileInfo refers to, excluding the path.

范例：

QFileInfo fi("/tmp/archive.tar.gz");
QString name = fi.fileName();                // name = "archive.tar.gz"

注意： 若此 QFileInfo is given a path ending with a directory separator '/' , the entry's name part is considered empty.

另请参阅 isRelative (), filePath (), baseName ()，和 suffix ().

QString QFileInfo:: filePath () const

Returns the path of the file system entry this QFileInfo refers to; the path may be absolute or relative.

另请参阅 absoluteFilePath (), canonicalFilePath ()，和 isRelative ().

QDateTime QFileInfo:: fileTime ( QFileDevice::FileTime time ) const

返回文件时间指定通过 time .

If the time cannot be determined, an invalid date time is returned.

If the file is a symlink, this function returns information about the target, not the symlink.

此函数重载 QFileInfo::fileTime (QFileDevice::FileTime, const QTimeZone &), and returns the same as fileTime(time, QTimeZone::LocalTime) .

另请参阅 birthTime (), lastModified (), lastRead ()，和 metadataChangeTime ().

`[since 6.6]` QDateTime QFileInfo:: fileTime ( QFileDevice::FileTime time , const QTimeZone & tz ) const

返回文件时间指定通过 time .

If the time cannot be determined, an invalid date time is returned.

If the file is a symlink, this function returns information about the target, not the symlink.

该函数在 Qt 6.6 引入。

另请参阅 birthTime (const QTimeZone &), lastModified (const QTimeZone &), lastRead (const QTimeZone &), metadataChangeTime (const QTimeZone &), and QDateTime::isValid ().

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemAbsoluteFilePath () const

返回 absoluteFilePath () as a std::filesystem::path .

该函数在 Qt 6.0 引入。

另请参阅 absoluteFilePath ().

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemAbsolutePath () const

返回 absolutePath () as a std::filesystem::path .

该函数在 Qt 6.0 引入。

另请参阅 absolutePath ().

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemCanonicalFilePath () const

返回 canonicalFilePath () as a std::filesystem::path .

该函数在 Qt 6.0 引入。

另请参阅 canonicalFilePath ().

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemCanonicalPath () const

返回 canonicalPath () as a std::filesystem::path .

该函数在 Qt 6.0 引入。

另请参阅 canonicalPath ().

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemFilePath () const

返回 filePath () as a std::filesystem::path .

该函数在 Qt 6.0 引入。

另请参阅 filePath ().

`[since 6.2]` std::filesystem::path QFileInfo:: filesystemJunctionTarget () const

返回 junctionTarget () as a std::filesystem::path .

该函数在 Qt 6.2 引入。

另请参阅 junctionTarget ().

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemPath () const

返回 path () as a std::filesystem::path .

该函数在 Qt 6.0 引入。

另请参阅 path ().

`[since 6.6]` std::filesystem::path QFileInfo:: filesystemReadSymLink () const

返回 readSymLink () as a std::filesystem::path .

该函数在 Qt 6.6 引入。

另请参阅 readSymLink ().

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemSymLinkTarget () const

返回 symLinkTarget () as a std::filesystem::path .

该函数在 Qt 6.0 引入。

另请参阅 symLinkTarget ().

QString QFileInfo:: group () const

Returns the group of the file. On Windows, on systems where files do not have groups, or if an error occurs, an empty string is returned.

This function can be time consuming under Unix (in the order of milliseconds).

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 groupId (), owner ()，和 ownerId ().

uint QFileInfo:: groupId () const

Returns the id of the group the file belongs to.

On Windows and on systems where files do not have groups this function always returns (uint) -2.

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 group (), owner ()，和 ownerId ().

bool QFileInfo:: isAbsolute () const

返回 true if the file system entry's path is absolute, otherwise returns false (that is, the path is relative).

注意： Paths starting with a colon ( : ) are always considered absolute, as they denote a QResource .

另请参阅 isRelative ().

`[since 6.4]` bool QFileInfo:: isAlias () const

返回 true if this object points to an alias; otherwise returns false .

Aliases only exist on macOS. They are treated as regular files, so opening an alias will open the file itself. In order to open the file or directory an alias references use symLinkTarget ().

注意： Even if an alias points to a non existing file, isAlias() returns true.

该函数在 Qt 6.4 引入。

另请参阅 isFile (), isDir (), isSymLink ()，和 symLinkTarget ().

bool QFileInfo:: isBundle () const

返回 true if this object points to a bundle or to a symbolic link to a bundle on macOS and iOS; otherwise returns false .

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 isDir (), isSymLink ()，和 isFile ().

bool QFileInfo:: isDir () const

返回 true if this object points to a directory or to a symbolic link to a directory. Returns false if the object points to something that is not a directory (such as a file) or that does not exist.

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 isFile (), isSymLink ()，和 isBundle ().

bool QFileInfo:: isExecutable () const

返回 true if the file system entry this QFileInfo refers to is executable; otherwise returns false .

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 isReadable (), isWritable ()，和 permission ().

bool QFileInfo:: isFile () const

返回 true if this object points to a file or to a symbolic link to a file. Returns false if the object points to something that is not a file (such as a directory) or that does not exist.

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 isDir (), isSymLink ()，和 isBundle ().

bool QFileInfo:: isHidden () const

返回 true if the file system entry this QFileInfo refers to is `hidden'; otherwise returns false .

注意： 此函数返回 true for the special entries "." and ".." on Unix, even though QDir::entryList treats them as shown. And note that, since this function inspects the file name, on Unix it will inspect the name of the symlink, if this file is a symlink, not the target's name.

On Windows, this function returns true if the target file is hidden (not the symlink).

bool QFileInfo:: isJunction () const

返回 true if the object points to a junction; otherwise returns false .

Junctions only exist on Windows' NTFS file system, and are typically created by the mklink command. They can be thought of as symlinks for directories, and can only be created for absolute paths on the local volume.

bool QFileInfo:: isNativePath () const

返回 true if the file path can be used directly with native APIs. Returns false if the file is otherwise supported by a virtual file system inside Qt, such as Qt 资源系统 .

注意： Native paths may still require conversion of path separators and character encoding, depending on platform and input requirements of the native API.

另请参阅 QDir::toNativeSeparators (), QFile::encodeName (), filePath (), absoluteFilePath ()，和 canonicalFilePath ().

bool QFileInfo:: isReadable () const

返回 true if the user can read the file system entry this QFileInfo refers to; otherwise returns false .

If the file is a symlink, this function returns information about the target, not the symlink.

注意： 若 NTFS permissions check has not been enabled, the result on Windows will merely reflect whether the entry exists.

另请参阅 isWritable (), isExecutable ()，和 permission ().

bool QFileInfo:: isRelative () const

返回 true if the file system entry's path is relative, otherwise returns false (that is, the path is absolute).

On Unix, absolute paths begin with the directory separator '/' . On Windows, absolute paths begin with a drive specification (for example, D:/ ).

注意： Paths starting with a colon ( : ) are always considered absolute, as they denote a QResource .

另请参阅 isAbsolute ().

bool QFileInfo:: isRoot () const

返回 true if the object points to a directory or to a symbolic link to a directory, and that directory is the root directory; otherwise returns false .

bool QFileInfo:: isShortcut () const

返回 true if this object points to a shortcut; otherwise returns false .

Shortcuts only exist on Windows and are typically .lnk files. For instance, true will be returned for shortcuts ( *.lnk files) on Windows, but false will be returned on Unix (including macOS and iOS).

The shortcut (.lnk) files are treated as regular files. Opening those will open the .lnk file itself. In order to open the file a shortcut references to, it must uses symLinkTarget () on a shortcut.

注意： Even if a shortcut (broken shortcut) points to a non existing file, isShortcut() returns true.

另请参阅 isFile (), isDir (), isSymbolicLink ()，和 symLinkTarget ().

bool QFileInfo:: isSymLink () const

返回 true if this object points to a symbolic link, shortcut, or alias; otherwise returns false .

Symbolic links exist on Unix (including macOS and iOS) and Windows and are typically created by the ln -s or mklink commands, respectively. Opening a symbolic link effectively opens the link's target .

In addition, true will be returned for shortcuts ( *.lnk files) on Windows, and aliases on macOS. This behavior is deprecated and will likely change in a future version of Qt. Opening a shortcut or alias will open the .lnk or alias file itself.

范例：

QFileInfo info(fileName);
if (info.isSymLink())
    fileName = info.symLinkTarget();

注意： exists () 返回 true if the symlink points to an existing target, otherwise it returns false .

另请参阅 isFile (), isDir ()，和 symLinkTarget ().

bool QFileInfo:: isSymbolicLink () const

返回 true if this object points to a symbolic link; otherwise returns false .

Symbolic links exist on Unix (including macOS and iOS) and Windows (NTFS-symlink) and are typically created by the ln -s or mklink commands, respectively.

Unix handles symlinks transparently. Opening a symbolic link effectively opens the link's target .

In contrast to isSymLink (), false will be returned for shortcuts ( *.lnk files) on Windows and aliases on macOS. Use QFileInfo::isShortcut () 和 QFileInfo::isAlias () 代替。

注意： exists () 返回 true if the symlink points to an existing target, otherwise it returns false .

另请参阅 isFile (), isDir (), isShortcut ()，和 symLinkTarget ().

bool QFileInfo:: isWritable () const

返回 true if the user can write to the file system entry this QFileInfo refers to; otherwise returns false .

If the file is a symlink, this function returns information about the target, not the symlink.

注意： 若 NTFS permissions check has not been enabled, the result on Windows will merely reflect whether the entry is marked as Read Only.

另请参阅 isReadable (), isExecutable ()，和 permission ().

`[since 6.2]` QString QFileInfo:: junctionTarget () const

Resolves an NTFS junction to the path it references.

Returns the absolute path to the directory an NTFS junction points to, or an empty string if the object is not an NTFS junction.

There is no guarantee that the directory named by the NTFS junction actually exists.

该函数在 Qt 6.2 引入。

另请参阅 isJunction (), isFile (), isDir (), isSymLink (), isSymbolicLink ()，和 isShortcut ().

QDateTime QFileInfo:: lastModified () const

Returns the date and time when the file was last modified.

If the file is a symlink, this function returns information about the target, not the symlink.

此函数重载 QFileInfo::lastModified (const QTimeZone &), and returns the same as lastModified(QTimeZone::LocalTime) .

另请参阅 birthTime (), lastRead (), metadataChangeTime ()，和 fileTime ().

`[since 6.6]` QDateTime QFileInfo:: lastModified (const QTimeZone & tz ) const

Returns the date and time when the file was last modified.

If the file is a symlink, this function returns information about the target, not the symlink.

该函数在 Qt 6.6 引入。

另请参阅 birthTime (const QTimeZone &), lastRead (const QTimeZone &), metadataChangeTime (const QTimeZone &), and fileTime (QFileDevice::FileTime, const QTimeZone &).

QDateTime QFileInfo:: lastRead () const

Returns the date and time when the file was last read (accessed).

On platforms where this information is not available, returns the same time as lastModified ().

If the file is a symlink, this function returns information about the target, not the symlink.

此函数重载 QFileInfo::lastRead (const QTimeZone &), and returns the same as lastRead(QTimeZone::LocalTime) .

另请参阅 birthTime (), lastModified (), metadataChangeTime ()，和 fileTime ().

`[since 6.6]` QDateTime QFileInfo:: lastRead (const QTimeZone & tz ) const

Returns the date and time when the file was last read (accessed).

On platforms where this information is not available, returns the same time as lastModified ().

If the file is a symlink, this function returns information about the target, not the symlink.

该函数在 Qt 6.6 引入。

另请参阅 birthTime (const QTimeZone &), lastModified (const QTimeZone &), metadataChangeTime (const QTimeZone &), and fileTime (QFileDevice::FileTime, const QTimeZone &).

bool QFileInfo:: makeAbsolute ()

If the file system entry's path is relative, this method converts it to an absolute path and returns true ; if the path is already absolute, this method returns false .

另请参阅 filePath () 和 isRelative ().

QDateTime QFileInfo:: metadataChangeTime () const

Returns the date and time when the file's metadata was last changed, in local time.

A metadata change occurs when the file is first created, but it also occurs whenever the user writes or sets inode information (for example, changing the file permissions).

If the file is a symlink, this function returns information about the target, not the symlink.

This function overloads QFileInfo::metadataChangeTime(const QTimeZone &tz), and returns the same as metadataChangeTime(QTimeZone::LocalTime) .

另请参阅 birthTime (), lastModified (), lastRead ()，和 fileTime ().

`[since 6.6]` QDateTime QFileInfo:: metadataChangeTime (const QTimeZone & tz ) const

Returns the date and time when the file's metadata was last changed. A metadata change occurs when the file is first created, but it also occurs whenever the user writes or sets inode information (for example, changing the file permissions).

If the file is a symlink, this function returns information about the target, not the symlink.

该函数在 Qt 6.6 引入。

另请参阅 birthTime (const QTimeZone &), lastModified (const QTimeZone &), lastRead (const QTimeZone &), and fileTime (QFileDevice::FileTime time, const QTimeZone &).

QString QFileInfo:: owner () const

Returns the owner of the file. On systems where files do not have owners, or if an error occurs, an empty string is returned.

This function can be time consuming under Unix (in the order of milliseconds). On Windows, it will return an empty string unless the NTFS permissions check has been enabled.

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 ownerId (), group ()，和 groupId ().

uint QFileInfo:: ownerId () const

Returns the id of the owner of the file.

On Windows and on systems where files do not have owners this function returns ((uint) -2).

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 owner (), group ()，和 groupId ().

QString QFileInfo:: path () const

Returns the path of the file system entry this QFileInfo refers to, excluding the entry's name.

注意： 若此 QFileInfo is given a path ending with a directory separator '/' , the entry's name part is considered empty. In this case, this function will return the entire path.

另请参阅 filePath (), absolutePath (), canonicalPath (), dir (), fileName ()，和 isRelative ().

bool QFileInfo:: permission ( QFileDevice::Permissions permissions ) const

Tests for file permissions. The permissions argument can be several flags of type QFile::Permissions OR-ed together to check for permission combinations.

On systems where files do not have permissions this function always returns true .

注意： The result might be inaccurate on Windows if the NTFS permissions check has not been enabled.

范例：

QFileInfo fi("/tmp/archive.tar.gz");
if (fi.permission(QFile::WriteUser | QFile::ReadGroup))
    qWarning("I can change the file; my group can read the file");
if (fi.permission(QFile::WriteGroup | QFile::WriteOther))
    qWarning("The group or others can change the file");

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 isReadable (), isWritable ()，和 isExecutable ().

QFileDevice::Permissions QFileInfo:: permissions () const

Returns the complete OR-ed together combination of QFile::Permissions for the file.

注意： The result might be inaccurate on Windows if the NTFS permissions check has not been enabled.

If the file is a symlink, this function returns information about the target, not the symlink.

`[since 6.6]` QString QFileInfo:: readSymLink () const

Read the path the symlink references.

Returns the raw path referenced by the symbolic link, without resolving a relative path relative to the directory containing the symbolic link. The returned string will only be an absolute path if the symbolic link actually references it as such. Returns an empty string if the object is not a symbolic link.

该函数在 Qt 6.6 引入。

另请参阅 symLinkTarget (), exists (), isSymLink (), isDir ()，和 isFile ().

void QFileInfo:: refresh ()

Refreshes the information about the file system entry this QFileInfo refers to, that is, reads in information from the file system the next time a cached property is fetched.

void QFileInfo:: setCaching ( bool enable )

若 enable is true, enables caching of file information. If enable is false caching is disabled.

When caching is enabled, QFileInfo reads the file information from the file system the first time it's needed, but generally not later.

Caching is enabled by default.

另请参阅 refresh () 和 caching ().

void QFileInfo:: setFile (const QString & path )

Sets the path of the file system entry that this QFileInfo provides information about to path that can be absolute or relative.

On Unix, absolute paths begin with the directory separator '/' . On Windows, absolute paths begin with a drive specification (for example, D:/ ).

Relative paths begin with a directory name or a regular file name and specify a file system entry's path relative to the current working directory.

范例：

QFileInfo info("/usr/bin/env");
QString path = info.absolutePath(); // path = /usr/bin
QString base = info.baseName(); // base = env
info.setFile("/etc/hosts");
path = info.absolutePath(); // path = /etc
base = info.baseName(); // base = hosts

另请参阅 isFile (), isRelative (), QDir::setCurrent ()，和 QDir::isRelativePath ().

void QFileInfo:: setFile (const QFileDevice & file )

这是重载函数。

Sets the file that the QFileInfo provides information about to file .

若 file includes a relative path, the QFileInfo will also have a relative path.

另请参阅 isRelative ().

void QFileInfo:: setFile (const QDir & dir , const QString & path )

这是重载函数。

Sets the path of the file system entry that this QFileInfo provides information about to path in directory dir .

若 dir has a relative path, the QFileInfo will also have a relative path.

若 path is absolute, then the directory specified by dir will be disregarded.

另请参阅 isRelative ().

`[since 6.0]` void QFileInfo:: setFile (const std::filesystem::path & path )

Sets the path of file system entry that this QFileInfo provides information about to path .

若 path is relative, the QFileInfo will also have a relative path.

该函数在 Qt 6.0 引入。

qint64 QFileInfo:: size () const

Returns the file size in bytes. If the file does not exist or cannot be fetched, 0 is returned.

If the file is a symlink, this function returns information about the target, not the symlink.

另请参阅 exists ().

`[since 6.0]` void QFileInfo:: stat ()

Reads all attributes from the file system.

This is useful when information about the file system is collected in a worker thread, and then passed to the UI in the form of caching QFileInfo 实例。

该函数在 Qt 6.0 引入。

另请参阅 setCaching () 和 refresh ().

QString QFileInfo:: suffix () const

Returns the suffix (extension) of the file.

The suffix consists of all characters in the file after (but not including) the last '.'.

范例：

QFileInfo fi("/tmp/archive.tar.gz");
QString ext = fi.suffix();  // ext = "gz"

The suffix of a file is computed equally on all platforms, independent of file naming conventions (e.g., ".bashrc" on Unix has an empty base name, and the suffix is "bashrc").

另请参阅 fileName (), completeSuffix (), baseName ()，和 completeBaseName ().

`[noexcept]` void QFileInfo:: swap ( QFileInfo & other )

Swaps this file info with other 。此函数非常快且从不失败。

QString QFileInfo:: symLinkTarget () const

Returns the absolute path to the file or directory a symbolic link points to, or an empty string if the object isn't a symbolic link.

此名称可能不表示现有文件；它只是字符串。

注意： exists () 返回 true if the symlink points to an existing target, otherwise it returns false .

另请参阅 exists (), isSymLink (), isDir ()，和 isFile ().

bool QFileInfo:: operator!= (const QFileInfo & fileinfo ) const

返回 true 若此 QFileInfo refers to a different file system entry than the one referred to by fileinfo ；否则返回 false .

另请参阅 operator== ().

QFileInfo &QFileInfo:: operator= (const QFileInfo & fileinfo )

Makes a copy of the given fileinfo 并将其赋值给此 QFileInfo .

`[noexcept]` QFileInfo &QFileInfo:: operator= ( QFileInfo && other )

移动赋值 other 到此 QFileInfo 实例。

bool QFileInfo:: operator== (const QFileInfo & fileinfo ) const

返回 true 若此 QFileInfo and fileinfo refer to the same entry on the file system; otherwise returns false .

Note that the result of comparing two empty QFileInfo objects, containing no file system entry references (paths that do not exist or are empty), is undefined.

警告： This will not compare two different symbolic links pointing to the same target.

警告： On Windows, long and short paths that refer to the same file system entry are treated as if they referred to different entries.

另请参阅 operator!= ().

宏文档编制

`[since 6.0]` QT_IMPLICIT_QFILEINFO_CONSTRUCTION

Defining this macro makes most QFileInfo constructors implicit instead of explicit. Since construction of QFileInfo objects is expensive, one should avoid accidentally creating them, especially if cheaper alternatives exist. For instance:

QDirIterator it(dir);
while (it.hasNext()) {
    // Implicit conversion from QString (returned by it.next()):
    // may create unnecessary data structures and cause additional
    // accesses to the file system. Unless this macro is defined,
    // this line does not compile.
    QFileInfo fi = it.next();
    ~~~
}

Instead, use the right API:

QDirIterator it(dir);
while (it.hasNext()) {
    // Extract the QFileInfo from the iterator directly:
    QFileInfo fi = it.nextFileInfo();
    ~~~
}

Construction from QString , QFile , and so on is always possible by using direct initialization instead of copy initialization:

QFileInfo fi1 = some_string; // Does not compile unless this macro is defined
QFileInfo fi2(some_string);  // OK
QFileInfo fi3{some_string};  // Possibly better, avoids the risk of the Most Vexing Parse
auto fi4 = QFileInfo(some_string); // OK

This macro is provided for compatibility reason. Its usage is not recommended in new code.

该宏在 Qt 6.0 引入。

QFileInfo 类

公共函数

静态公共成员

相关非成员

宏

详细描述

Symbolic Links and Shortcuts

NTFS permissions

性能注意事项

平台具体问题

成员函数文档编制

QFileInfo:: QFileInfo ()

[explicit] QFileInfo:: QFileInfo (const QString & path )

[explicit] QFileInfo:: QFileInfo (const QFileDevice & file )

[explicit] QFileInfo:: QFileInfo (const QDir & dir , const QString & path )

[since 6.0] QFileInfo:: QFileInfo (const std::filesystem::path & file )

[since 6.0] QFileInfo:: QFileInfo (const QDir & dir , const std::filesystem::path & path )

QFileInfo:: QFileInfo (const QFileInfo & fileinfo )

[noexcept] QFileInfo:: ~QFileInfo ()

QDir QFileInfo:: absoluteDir () const

QString QFileInfo:: absoluteFilePath () const

QString QFileInfo:: absolutePath () const

QString QFileInfo:: baseName () const

QDateTime QFileInfo:: birthTime () const

[since 6.6] QDateTime QFileInfo:: birthTime (const QTimeZone & tz ) const

QString QFileInfo:: bundleName () const

bool QFileInfo:: caching () const

QString QFileInfo:: canonicalFilePath () const

QString QFileInfo:: canonicalPath () const

QString QFileInfo:: completeBaseName () const

QString QFileInfo:: completeSuffix () const

QDir QFileInfo:: dir () const

bool QFileInfo:: exists () const

[static] bool QFileInfo:: exists (const QString & path )

QString QFileInfo:: fileName () const

QString QFileInfo:: filePath () const

QDateTime QFileInfo:: fileTime ( QFileDevice::FileTime time ) const

[since 6.6] QDateTime QFileInfo:: fileTime ( QFileDevice::FileTime time , const QTimeZone & tz ) const

[since 6.0] std::filesystem::path QFileInfo:: filesystemAbsoluteFilePath () const

[since 6.0] std::filesystem::path QFileInfo:: filesystemAbsolutePath () const

[since 6.0] std::filesystem::path QFileInfo:: filesystemCanonicalFilePath () const

[since 6.0] std::filesystem::path QFileInfo:: filesystemCanonicalPath () const

[since 6.0] std::filesystem::path QFileInfo:: filesystemFilePath () const

[since 6.2] std::filesystem::path QFileInfo:: filesystemJunctionTarget () const

[since 6.0] std::filesystem::path QFileInfo:: filesystemPath () const

[since 6.6] std::filesystem::path QFileInfo:: filesystemReadSymLink () const

[since 6.0] std::filesystem::path QFileInfo:: filesystemSymLinkTarget () const

QString QFileInfo:: group () const

uint QFileInfo:: groupId () const

bool QFileInfo:: isAbsolute () const

[since 6.4] bool QFileInfo:: isAlias () const

bool QFileInfo:: isBundle () const

bool QFileInfo:: isDir () const

bool QFileInfo:: isExecutable () const

bool QFileInfo:: isFile () const

bool QFileInfo:: isHidden () const

bool QFileInfo:: isJunction () const

bool QFileInfo:: isNativePath () const

bool QFileInfo:: isReadable () const

bool QFileInfo:: isRelative () const

bool QFileInfo:: isRoot () const

bool QFileInfo:: isShortcut () const

bool QFileInfo:: isSymLink () const

bool QFileInfo:: isSymbolicLink () const

bool QFileInfo:: isWritable () const

[since 6.2] QString QFileInfo:: junctionTarget () const

QDateTime QFileInfo:: lastModified () const

[since 6.6] QDateTime QFileInfo:: lastModified (const QTimeZone & tz ) const

QDateTime QFileInfo:: lastRead () const

[since 6.6] QDateTime QFileInfo:: lastRead (const QTimeZone & tz ) const

bool QFileInfo:: makeAbsolute ()

QDateTime QFileInfo:: metadataChangeTime () const

[since 6.6] QDateTime QFileInfo:: metadataChangeTime (const QTimeZone & tz ) const

QString QFileInfo:: owner () const

uint QFileInfo:: ownerId () const

QString QFileInfo:: path () const

bool QFileInfo:: permission ( QFileDevice::Permissions permissions ) const

QFileDevice::Permissions QFileInfo:: permissions () const

[since 6.6] QString QFileInfo:: readSymLink () const

void QFileInfo:: refresh ()

`[explicit]` QFileInfo:: QFileInfo (const QString & path )

`[explicit]` QFileInfo:: QFileInfo (const QFileDevice & file )

`[explicit]` QFileInfo:: QFileInfo (const QDir & dir , const QString & path )

`[since 6.0]` QFileInfo:: QFileInfo (const std::filesystem::path & file )

`[since 6.0]` QFileInfo:: QFileInfo (const QDir & dir , const std::filesystem::path & path )

`[noexcept]` QFileInfo:: ~QFileInfo ()

`[since 6.6]` QDateTime QFileInfo:: birthTime (const QTimeZone & tz ) const

`[static]` bool QFileInfo:: exists (const QString & path )

`[since 6.6]` QDateTime QFileInfo:: fileTime ( QFileDevice::FileTime time , const QTimeZone & tz ) const

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemAbsoluteFilePath () const

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemAbsolutePath () const

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemCanonicalFilePath () const

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemCanonicalPath () const

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemFilePath () const

`[since 6.2]` std::filesystem::path QFileInfo:: filesystemJunctionTarget () const

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemPath () const

`[since 6.6]` std::filesystem::path QFileInfo:: filesystemReadSymLink () const

`[since 6.0]` std::filesystem::path QFileInfo:: filesystemSymLinkTarget () const

`[since 6.4]` bool QFileInfo:: isAlias () const

`[since 6.2]` QString QFileInfo:: junctionTarget () const

`[since 6.6]` QDateTime QFileInfo:: lastModified (const QTimeZone & tz ) const

`[since 6.6]` QDateTime QFileInfo:: lastRead (const QTimeZone & tz ) const

`[since 6.6]` QDateTime QFileInfo:: metadataChangeTime (const QTimeZone & tz ) const

`[since 6.6]` QString QFileInfo:: readSymLink () const

`[since 6.0]` void QFileInfo:: setFile (const std::filesystem::path & path )

`[since 6.0]` void QFileInfo:: stat ()

`[noexcept]` void QFileInfo:: swap ( QFileInfo & other )

`[noexcept]` QFileInfo &QFileInfo:: operator= ( QFileInfo && other )

`[since 6.0]` QT_IMPLICIT_QFILEINFO_CONSTRUCTION