QFileInfo 类

QFileInfo 类提供与系统无关的文件信息。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 & file )
	QFileInfo (const QFileDevice & file )
	QFileInfo (const QDir & dir , const QString & file )
	QFileInfo (const std::filesystem::path & file )
	QFileInfo (const QDir & dir , const std::filesystem::path & file )
	QFileInfo (const QFileInfo & fileinfo )
	~QFileInfo ()
QDir	absoluteDir () const
QString	absoluteFilePath () const
QString	absolutePath () const
QString	baseName () const
QDateTime	birthTime () 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 (QFile::FileTime time ) const
std::filesystem::path	filesystemAbsoluteFilePath () const
std::filesystem::path	filesystemAbsolutePath () const
std::filesystem::path	filesystemCanonicalFilePath () const
std::filesystem::path	filesystemCanonicalPath () const
std::filesystem::path	filesystemFilePath () const
std::filesystem::path	filesystemJunctionTarget () const
std::filesystem::path	filesystemPath () const
std::filesystem::path	filesystemSymLinkTarget () const
QString	group () const
uint	groupId () const
bool	isAbsolute () const
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
QString	junctionTarget () const
QDateTime	lastModified () const
QDateTime	lastRead () const
bool	makeAbsolute ()
QDateTime	metadataChangeTime () const
QString	owner () const
uint	ownerId () const
QString	path () const
bool	permission (QFile::Permissions permissions ) const
QFile::Permissions	permissions () const
void	refresh ()
void	setCaching (bool enable )
void	setFile (const QString & file )
void	setFile (const QFileDevice & file )
void	setFile (const QDir & dir , const QString & file )
void	setFile (const std::filesystem::path & file )
qint64	size () const
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 & file )

QFileInfoList

宏

QT_IMPLICIT_QFILEINFO_CONSTRUCTION

详细描述

QFileInfo 提供有关文件在文件系统中的名称位置 (路径)、访问权限及它是目录还是符号链接、等信息。文件的大小、最后修改/读取时间也是可用的。QFileInfo 也可以被用于获取信息有关 Qt resource .

A QFileInfo can point to a file with either a relative or an absolute file path. Absolute file paths begin with the directory separator "/" (or with a drive specification on Windows). Relative file names begin with a directory name or a file name and specify a path relative to the current working directory. An example of an absolute path is the string "/tmp/quartz". A relative path might look like "src/fatlib". You can use the function isRelative () to check whether a QFileInfo is using a relative or an absolute file 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 that the QFileInfo works on is set in the constructor or later with setFile ()。使用 exists () to see if the file exists and size () to get its size.

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

On Unix (including macOS and iOS), the property getter functions in this class return the properties such as times and size of the target file, 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 targeted file, 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

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

The file's dates are returned by birthTime (), lastModified (), lastRead () 和 fileTime (). Information about the file's access permissions is obtained with isReadable (), isWritable () 和 isExecutable (). The file's ownership is available from owner (), ownerId (), group () 和 groupId (). You can examine a file's permissions and ownership in a single statement using the permission () 函数。

注意： 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。

性能问题

QFileInfo 的某些函数查询文件系统，但出于性能原因，有些函数仅运转于文件名本身。例如：要返回相对文件名的绝对路径， 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。

注意： 为提高性能，QFileInfo 缓存文件的有关信息。

Because files can be changed by other users or programs, or even by other parts of the same program, there is a function that refreshes the file information: refresh (). If you want to switch off a QFileInfo's caching and force it to access the file system every time you request information from it call setCaching (false). If you want to make sure that all information is read from the file system, use stat ().

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 which implements Android's native file picker.
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.

Note that an empty QFileInfo object contain no file reference.

另请参阅 setFile ().

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

Constructs a new QFileInfo that gives information about the given file. The file can also include an absolute or 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 & file )

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

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

若 file is an absolute path, 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 & file )

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

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

若 file is an absolute path, 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 .

QFileInfo:: ~QFileInfo ()

销毁 QFileInfo and frees its resources.

QDir QFileInfo:: absoluteDir () const

Returns the file's absolute path as a QDir 对象。

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

QString QFileInfo:: absoluteFilePath () const

Returns an absolute path including the file name.

The absolute path name consists of the full path and the file name. On Unix this will always begin with the root, '/', directory. On Windows this will always begin 'D:/' where D is a drive letter, except for network shares that are not mapped to a drive letter, in which case the path will begin '//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 a file's path absolute path. This doesn't include the file name.

On Unix the absolute path will always begin with the root, '/', directory. On Windows this will always begin 'D:/' where D is a drive letter, except for network shares that are not mapped to a drive letter, in which case the path will begin '//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.

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

If the file is a symlink, the time of the target file is returned (not the symlink).

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

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 canonical path including the file name, i.e. an absolute path without symbolic links or redundant "." or ".." elements.

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

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

QString QFileInfo:: canonicalPath () const

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

If the file does not exist, canonicalPath() 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

Returns the path of the object's parent directory as a QDir 对象。

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 若文件存在；否则返回 false .

注意： 若文件是指向不存在文件的符号链接，返回 false。

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

返回 true 若 file 存在；否则返回 false .

注意： 若 file 是指向不存在文件的符号链接，返回 false。

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

QString QFileInfo:: fileName () const

返回文件的名称，排除路径。

范例：

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

注意，若此 QFileInfo 给定以斜杠结尾的路径，认为文件名是空的。

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

QString QFileInfo:: filePath () const

Returns the file name, including the path (which may be absolute or relative).

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

QDateTime QFileInfo:: fileTime ( QFile::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, the time of the target file is returned (not the symlink).

另请参阅 QFile::FileTime 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 6.0]` 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 the owning group of 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 the id of the group owning the target (not the symlink).

另请参阅 group (), owner ()，和 ownerId ().

bool QFileInfo:: isAbsolute () const

返回 true if the file path is absolute, otherwise returns false (i.e. 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 true if the target is a bundle (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; otherwise returns false .

If the file is a symlink, this function returns true if the target is a directory (not the symlink).

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

bool QFileInfo:: isExecutable () const

返回 true if the file is executable; otherwise returns false .

If the file is a symlink, this function returns true if the target is executable (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 which isn't a file, such as a directory.

If the file is a symlink, this function returns true if the target is a regular file (not the symlink).

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

bool QFileInfo:: isHidden () const

返回 true if this is a `hidden' file; otherwise returns false .

注意： 此函数返回 true for the special entries "." and ".." on Unix, even though QDir::entryList threats 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; otherwise returns false .

If the file is a symlink, this function returns true if the target is readable (not the symlink).

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

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

bool QFileInfo:: isRelative () const

返回 true if the file path is relative, otherwise returns false (i.e. the path is absolute). (E.g. under Unix a path is absolute if it begins with a "/").

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： If the symlink points to a non existing file, exists () 返回 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： If the symlink points to a non existing file, exists () 返回 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; otherwise returns false .

If the file is a symlink, this function returns true if the target is writeable (not the symlink).

注意： 若 NTFS permissions check has not been enabled, the result on Windows will merely reflect whether the file 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 local time when the file was last modified.

If the file is a symlink, the time of the target file is returned (not the symlink).

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

QDateTime QFileInfo:: lastRead () const

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

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

If the file is a symlink, the time of the target file is returned (not the symlink).

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

bool QFileInfo:: makeAbsolute ()

Converts the file's path to an absolute path if it is not already in that form. Returns true to indicate that the path was converted; otherwise returns false to indicate that the path was already absolute.

另请参阅 filePath () 和 isRelative ().

QDateTime QFileInfo:: metadataChangeTime () const

Returns the date and time when the file metadata was changed. A metadata change occurs when the file is 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, the time of the target file is returned (not the symlink).

另请参阅 lastModified () 和 lastRead ().

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 the owner of 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 the id of the owner of the target (not the symlink).

另请参阅 owner (), group ()，和 groupId ().

QString QFileInfo:: path () const

Returns the file's path. This doesn't include the file name.

注意，若此 QFileInfo object is given a path ending in a slash, the name of the file is considered empty and this function will return the entire path.

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

bool QFileInfo:: permission ( QFile::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 checks the permissions of the target (not the symlink).

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

QFile::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 the permissions of the target (not the symlink).

void QFileInfo:: refresh ()

Refreshes the information about the file, i.e. 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 & file )

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

The file can also include an absolute or relative file path. Absolute paths begin with the directory separator (e.g. "/" under Unix) or a drive specification (under Windows). Relative file names begin with a directory name or a file name and specify a path relative to the current 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 & file )

这是重载函数。

Sets the file that the QFileInfo provides information about to file in directory dir .

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

另请参阅 isRelative ().

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

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

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, the size of the target file is returned (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 ().

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。 QFileInfo::exists () 返回 true 若符号链接指向现有文件。

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

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

返回 true 若此 QFileInfo object refers to a different file than the one specified 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 .

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 object refers to a file in the same location as fileinfo ；否则返回 false .

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

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

警告： Long and short file names that refer to the same file on Windows are treated as if they referred to different files.

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

性能问题

平台具体问题

成员函数文档编制

QFileInfo:: QFileInfo ()

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

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

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

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

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

QFileInfo:: QFileInfo (const QFileInfo & fileinfo )

QFileInfo:: ~QFileInfo ()

QDir QFileInfo:: absoluteDir () const

QString QFileInfo:: absoluteFilePath () const

QString QFileInfo:: absolutePath () const

QString QFileInfo:: baseName () const

QDateTime QFileInfo:: birthTime () 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 & file )

QString QFileInfo:: fileName () const

QString QFileInfo:: filePath () const

QDateTime QFileInfo:: fileTime ( QFile::FileTime time ) 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 6.0] 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

QDateTime QFileInfo:: lastRead () const

bool QFileInfo:: makeAbsolute ()

QDateTime QFileInfo:: metadataChangeTime () const

QString QFileInfo:: owner () const

uint QFileInfo:: ownerId () const

QString QFileInfo:: path () const

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

QFile::Permissions QFileInfo:: permissions () const

void QFileInfo:: refresh ()

void QFileInfo:: setCaching ( bool enable )

void QFileInfo:: setFile (const QString & file )

void QFileInfo:: setFile (const QFileDevice & file )

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

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

qint64 QFileInfo:: size () const

[since 6.0] void QFileInfo:: stat ()

QString QFileInfo:: suffix () const

void QFileInfo:: swap ( QFileInfo & other )

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

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

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

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

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

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

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

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

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

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

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

`[since 6.0]` QT_IMPLICIT_QFILEINFO_CONSTRUCTION