com.trolltech.qt.core
Class QAbstractFileEngine

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QAbstractFileEngine
All Implemented Interfaces:
QtJambiInterface
Direct Known Subclasses:
QFSFileEngine

public class QAbstractFileEngine
extends QtJambiObject

The QAbstractFileEngine class provides an abstraction for accessing the filesystem. The QDir, QFile, and QFileInfo classes all make use of a QAbstractFileEngine internally. If you create your own QAbstractFileEngine subclass (and register it with Qt by creating a QAbstractFileEngineHandler subclass), your file engine will be used when the path is one that your file engine handles.

A QAbstractFileEngine refers to one file or one directory. If the referent is a file, the setFileName(), rename(), and remove() functions are applicable. If the referent is a directory the mkdir(), rmdir(), and entryList() functions are applicable. In all cases the caseSensitive(), isRelativePath(), fileFlags(), ownerId(), owner(), and fileTime() functions are applicable.

A QAbstractFileEngine subclass can be created to do synchronous network I/O based file system operations, local file system operations, or to operate as a resource system to access file based resources.

See also:
QAbstractFileEngineHandler.


Nested Class Summary
static class QAbstractFileEngine.Extension
          This enum describes the types of extensions that the file engine can support.
static class QAbstractFileEngine.FileFlag
          The permissions and types of a file, suitable for OR'ing together.
static class QAbstractFileEngine.FileFlags
           
static class QAbstractFileEngine.FileName
          These values are used to request a file name in a particular format.
static class QAbstractFileEngine.FileOwner
          See also.
owner(), ownerId(), and setFileName().
static class QAbstractFileEngine.FileTime
          These are used by the fileTime() function.
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
protected QAbstractFileEngine()
          Constructs a new QAbstractFileEngine that does not refer to any file or directory.
 
Method Summary
static void addSearchPathForResourceEngine(java.lang.String path)
          Adds path to the set of paths in which Qt Jambi should search for resources.
 boolean atEnd()
          Returns true if the current position is at the end of the file; otherwise, returns false.
 boolean caseSensitive()
          Should return true if the underlying file system is case-sensitive; otherwise return false.
 boolean close()
          Closes the file, returning true if successful; otherwise returns false.
 boolean copy(java.lang.String newName)
          Copies the contents of this file to a file with the name newName.
static QAbstractFileEngine create(java.lang.String fileName)
          Creates and returns a QAbstractFileEngine suitable for processing fileName.
 java.util.List entryList(QDir.Filters filters, java.util.List filterNames)
          Requests that a list of all the files matching the filters list based on the filterNames in the file engine's directory are returned.
 QFile.FileError error()
          Returns the QFile::FileError that resulted from the last failed operation.
 java.lang.String errorString()
          Returns the human-readable message appropriate to the current error reported by error().
 QAbstractFileEngine.FileFlags fileFlags()
          This function should return the set of OR'd flags that are true for the file engine's file, and that are in the type's OR'd members.
 QAbstractFileEngine.FileFlags fileFlags(QAbstractFileEngine.FileFlag[] type)
          This is an overloaded method provided for convenience.
 QAbstractFileEngine.FileFlags fileFlags(QAbstractFileEngine.FileFlags type)
          This function should return the set of OR'd flags that are true for the file engine's file, and that are in the type's OR'd members.
 java.lang.String fileName()
          Return the file engine's current file name in the format specified by file.
 java.lang.String fileName(QAbstractFileEngine.FileName file)
          Return the file engine's current file name in the format specified by file.
 QDateTime fileTime(QAbstractFileEngine.FileTime time)
          If time is CreationTime, return when the file was created.
 boolean flush()
          Flushes the open file, returning true if successful; otherwise returns false.
 int handle()
          Returns the native file handle for this file engine.
 boolean isRelativePath()
          Return true if the file referred to by this file engine has a relative path; otherwise return false.
 boolean isSequential()
          Returns true if the file is a sequential access device; returns false if the file is a direct access device.
 boolean link(java.lang.String newName)
          Creates a link from the file currently specified by fileName() to newName.
 boolean mkdir(java.lang.String dirName, boolean createParentDirectories)
          Requests that the directory dirName be created.
 boolean open(QIODevice.OpenMode openMode)
          Opens the file in the specified mode.
 boolean open(QIODevice.OpenModeFlag[] openMode)
          This is an overloaded method provided for convenience.
 java.lang.String owner(QAbstractFileEngine.FileOwner arg__1)
          If owner is OwnerUser return the name of the user who owns the file.
 int ownerId(QAbstractFileEngine.FileOwner arg__1)
          If owner is OwnerUser return the ID of the user who owns the file.
 long pos()
          Returns the current file position.
 long read(QNativePointer data, long maxlen)
          Reads a number of characters from the file into data.
 long readLine(QNativePointer data, long maxlen)
          This function reads one line, terminated by a '\n' character, from the file info data.
 boolean remove()
          Requests that the file is deleted from the file system.
static void removeSearchPathForResourceEngine(java.lang.String path)
          Removes path from the set of paths in which Qt Jambi searches for resources.
 boolean rename(java.lang.String newName)
          Requests that the file be renamed to newName in the file system.
 boolean rmdir(java.lang.String dirName, boolean recurseParentDirectories)
          Requests that the directory dirName is deleted from the file system.
 boolean seek(long pos)
          Sets the file position to the given offset.
protected  void setError(QFile.FileError error, java.lang.String str)
          Sets the error type to error, and the error string to errorString.
 void setFileName(java.lang.String file)
          Sets the file engine's file name to file.
 boolean setPermissions(int perms)
          Requests that the file's permissions be set to perms.
 boolean setSize(long size)
          Requests that the file be set to size size.
 long size()
          Returns the size of the file.
 boolean supportsExtension(QAbstractFileEngine.Extension extension)
          This virtual function returns true if the file engine supports extension; otherwise, false is returned.
 long write(QNativePointer data, long len)
          Writes len bytes from data to the file.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QAbstractFileEngine

protected QAbstractFileEngine()
Constructs a new QAbstractFileEngine that does not refer to any file or directory.

See also:
setFileName().

Method Detail

atEnd

public final boolean atEnd()
Returns true if the current position is at the end of the file; otherwise, returns false.

This function bases its behavior on calling extension() with AtEndExtension . If the engine does not support this extension, false is returned.

See also:
extension(), supportsExtension(), and QFile::atEnd().


error

public final QFile.FileError error()
Returns the QFile::FileError that resulted from the last failed operation. If QFile::UnspecifiedError is returned, QFile will use its own idea of the error status.

See also:
setError(), QFile::FileError , and errorString().


errorString

public final java.lang.String errorString()
Returns the human-readable message appropriate to the current error reported by error(). If no suitable string is available, an empty string is returned.

See also:
error().


setError

protected final void setError(QFile.FileError error,
                              java.lang.String str)
Sets the error type to error, and the error string to errorString. Call this function to set the error values returned by the higher-level classes.

See also:
QFile::error(), QIODevice::errorString(), and QIODevice::setErrorString().


caseSensitive

public boolean caseSensitive()
Should return true if the underlying file system is case-sensitive; otherwise return false.

This virtual function must be reimplemented by all subclasses.


close

public boolean close()
Closes the file, returning true if successful; otherwise returns false.

The default implementation always returns false.


copy

public boolean copy(java.lang.String newName)
Copies the contents of this file to a file with the name newName. Returns true on success; otherwise, false is returned.


entryList

public java.util.List entryList(QDir.Filters filters,
                                java.util.List filterNames)
Requests that a list of all the files matching the filters list based on the filterNames in the file engine's directory are returned.

Should return an empty list if the file engine refers to a file rather than a directory, or if the directory is unreadable or does not exist or if nothing matches the specifications.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName().


fileFlags

public final QAbstractFileEngine.FileFlags fileFlags(QAbstractFileEngine.FileFlag[] type)
This is an overloaded method provided for convenience.


fileFlags

public final QAbstractFileEngine.FileFlags fileFlags()
This function should return the set of OR'd flags that are true for the file engine's file, and that are in the type's OR'd members.

In your reimplementation you can use the type argument as an optimization hint and only return the OR'd set of members that are true and that match those in type; in other words you can ignore any members not mentioned in type, thus avoiding some potentially expensive lookups or system calls.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName().


fileFlags

public QAbstractFileEngine.FileFlags fileFlags(QAbstractFileEngine.FileFlags type)
This function should return the set of OR'd flags that are true for the file engine's file, and that are in the type's OR'd members.

In your reimplementation you can use the type argument as an optimization hint and only return the OR'd set of members that are true and that match those in type; in other words you can ignore any members not mentioned in type, thus avoiding some potentially expensive lookups or system calls.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName().


fileName

public final java.lang.String fileName()
Return the file engine's current file name in the format specified by file.

If you don't handle some FileName possibilities, return the file name set in setFileName() when an unhandled format is requested.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName(), and FileName .


fileName

public java.lang.String fileName(QAbstractFileEngine.FileName file)
Return the file engine's current file name in the format specified by file.

If you don't handle some FileName possibilities, return the file name set in setFileName() when an unhandled format is requested.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName(), and FileName .


fileTime

public QDateTime fileTime(QAbstractFileEngine.FileTime time)
If time is CreationTime, return when the file was created. If time is ModificationTime, return when the file was most recently modified. If time is AccessTime, return when the file was most recently accessed (e.g. read or written). If the time cannot be determined return QDateTime() (an invalid date time).

This virtual function must be reimplemented by all subclasses.

See also:
setFileName(), QDateTime, QDateTime::isValid(), and FileTime .


flush

public boolean flush()
Flushes the open file, returning true if successful; otherwise returns false.

The default implementation always returns false.


handle

public int handle()
Returns the native file handle for this file engine. This handle must be used with care; its value and type are platform specific, and using it will most likely lead to non-portable code.


isRelativePath

public boolean isRelativePath()
Return true if the file referred to by this file engine has a relative path; otherwise return false.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName().


isSequential

public boolean isSequential()
Returns true if the file is a sequential access device; returns false if the file is a direct access device.

Operations involving size() and seek(int) are not valid on sequential devices.


link

public boolean link(java.lang.String newName)
Creates a link from the file currently specified by fileName() to newName. What a link is depends on the underlying filesystem (be it a shortcut on Windows or a symbolic link on Unix). Returns true if successful; otherwise returns false.


mkdir

public boolean mkdir(java.lang.String dirName,
                     boolean createParentDirectories)
Requests that the directory dirName be created. If createParentDirectories is true, then any sub-directories in dirName that don't exist must be created. If createParentDirectories is false then any sub-directories in dirName must already exist for the function to succeed. If the operation succeeds return true; otherwise return false.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName(), rmdir(), and isRelativePath().


open

public final boolean open(QIODevice.OpenModeFlag[] openMode)
This is an overloaded method provided for convenience.


open

public boolean open(QIODevice.OpenMode openMode)
Opens the file in the specified mode. Returns true if the file was successfully opened; otherwise returns false.

The mode is an OR combination of QIODevice::OpenMode and QIODevice::HandlingMode values.


owner

public java.lang.String owner(QAbstractFileEngine.FileOwner arg__1)
If owner is OwnerUser return the name of the user who owns the file. If owner is OwnerGroup return the name of the group that own the file. If you can't determine the owner return QString().

This virtual function must be reimplemented by all subclasses.

See also:
ownerId(), setFileName(), and FileOwner .


ownerId

public int ownerId(QAbstractFileEngine.FileOwner arg__1)
If owner is OwnerUser return the ID of the user who owns the file. If owner is OwnerGroup return the ID of the group that own the file. If you can't determine the owner return -2.

This virtual function must be reimplemented by all subclasses.

See also:
owner(), setFileName(), and FileOwner .


pos

public long pos()
Returns the current file position.

This is the position of the data read/write head of the file.


read

public long read(QNativePointer data,
                 long maxlen)
Reads a number of characters from the file into data. At most maxlen characters will be read.

Returns -1 if a fatal error occurs, or 0 if there are no bytes to read.


readLine

public long readLine(QNativePointer data,
                     long maxlen)
This function reads one line, terminated by a '\n' character, from the file info data. At most maxlen characters will be read. The end-of-line character is included.


remove

public boolean remove()
Requests that the file is deleted from the file system. If the operation succeeds return true; otherwise return false.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName(), and rmdir().


rename

public boolean rename(java.lang.String newName)
Requests that the file be renamed to newName in the file system. If the operation succeeds return true; otherwise return false.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName().


rmdir

public boolean rmdir(java.lang.String dirName,
                     boolean recurseParentDirectories)
Requests that the directory dirName is deleted from the file system. When recurseParentDirectories is true, then any empty parent-directories in dirName must also be deleted. If recurseParentDirectories is false, only the dirName leaf-node should be deleted. In most file systems a directory cannot be deleted using this function if it is non-empty. If the operation succeeds return true; otherwise return false.

This virtual function must be reimplemented by all subclasses.

See also:
setFileName(), remove(), mkdir(), and isRelativePath().


seek

public boolean seek(long pos)
Sets the file position to the given offset. Returns true if the position was successfully set; otherwise returns false.

The offset is from the beginning of the file, unless the file is sequential.

See also:
isSequential().


setFileName

public void setFileName(java.lang.String file)
Sets the file engine's file name to file. This file name is the file that the rest of the virtual functions will operate on.

This virtual function must be reimplemented by all subclasses.

See also:
fileName(), and rename().


setPermissions

public boolean setPermissions(int perms)
Requests that the file's permissions be set to perms. The argument perms will be set to the OR-ed together combination of QAbstractFileEngine::FileInfo, with only the QAbstractFileEngine::PermsMask being honored. If the operations succceeds return true; otherwise return false;

This virtual function must be reimplemented by all subclasses.

See also:
size().


setSize

public boolean setSize(long size)
Requests that the file be set to size size. If size is larger than the current file then it is filled with 0's, if smaller it is simply truncated. If the operations succceeds return true; otherwise return false;

This virtual function must be reimplemented by all subclasses.

See also:
size().


size

public long size()
Returns the size of the file.

See also:
setSize().


supportsExtension

public boolean supportsExtension(QAbstractFileEngine.Extension extension)
This virtual function returns true if the file engine supports extension; otherwise, false is returned. By default, no extensions are supported.

See also:
extension().


write

public long write(QNativePointer data,
                  long len)
Writes len bytes from data to the file. Returns the number of characters written on success; otherwise returns -1.


create

public static QAbstractFileEngine create(java.lang.String fileName)
Creates and returns a QAbstractFileEngine suitable for processing fileName.

You should not need to call this function; use QFile, QFileInfo or QDir directly instead.

If you reimplemnt this function, it should only return file engines that knows how to handle fileName; otherwise, it should return 0.

See also:
QAbstractFileEngineHandler.


addSearchPathForResourceEngine

public static void addSearchPathForResourceEngine(java.lang.String path)
Adds path to the set of paths in which Qt Jambi should search for resources. Resources can be accessed using the "classpath:" scheme.


removeSearchPathForResourceEngine

public static void removeSearchPathForResourceEngine(java.lang.String path)
Removes path from the set of paths in which Qt Jambi searches for resources.