jfilesyslib

Class FileSystem

java.lang.Object

jfilesyslib.FileSystem

Direct Known Subclasses:

FullFileSystem, MemoryFs, MirrorFs

public abstract class FileSystem
extends java.lang.Object

Inherit from this class in order to get a basic, minimal file system. There are some non-abstract methods which should be implemented.

Author:

Marc Miltenberger

Constructor Summary

Constructors

Constructor and Description
FileSystem()

Method Summary

Methods

Modifier and Type	Method and Description
void	afterUnmounting() Is called after the file system has been unmounted successfully.
void	beforeMounting(java.lang.String mountPath) Is called directly before the file system is mounted
void	beforeUnmounting() Is called directly before the file system is unmounted
abstract void	close(FileHandle handle) Closes the file handle.
abstract void	createDirectory(java.lang.String path) Creates a new, empty directory.
abstract void	createFile(java.lang.String path) Creates a new (blank) file.
void	createHardLink(java.lang.String source, java.lang.String destination) Creates a hard link at source pointing to destination.
void	createSymbolicLink(java.lang.String source, java.lang.String destination) Creates a symbolic link at source pointing to destination.
void	delete(java.lang.String path) Checks whether path is a file or directory and calls the appropriate method
abstract void	deleteDirectoryRecursively(java.lang.String directory) Deletes a directory recursively.
abstract void	deleteFile(java.lang.String file) Deletes a file or symbolic link.
abstract void	flush(FileHandle handle) Should write all pending data in the cache.
abstract int	getBlockSize() Returns the block size in bytes
ExtendedAttribute	getExtendedAttribute(java.lang.String path, java.lang.String name) Returns one specific extended attribute.
abstract EntityInfo	getFileMetaData(java.lang.String path) Returns some meta data about the path.
int	getFilesFreeCount() Returns the number of files which may be created.
abstract java.lang.String	getFileSystemName() Returns the file system name
abstract long	getFreeBlockAvailableCount() Returns the number of free blocks, which are available to the current user.
abstract long	getFreeBlockCount() Returns the number of free blocks.
int	getMaxPathLength() Returns the maximum path length.
java.lang.String	getMountPath() Returns the mount path
int	getNumberOfFilesInDirectory(DirectoryInfo info) Returns the number of files (and direct subdirectories) in a directory
abstract long	getTotalBlockCount() Returns the number of total blocks.
int	getTotalFilesCount() Returns the total number of files on the volume.
UnixPermissions	getUnixPermissions(java.lang.String path) Returns the unix permissions
abstract java.lang.String	getVolumeName() Returns the volume name.
int	getVolumeSerialNumber() Returns a volume serial number
WindowsAttributes	getWindowsAttributes(java.lang.String path) Returns the windows attributes.
abstract boolean	isCaseSensitive() Returns true if the pathes are case sensitive
boolean	isCompressed() Returns true if the file system is compressed
boolean	isReadOnly() Returns true if the file system is read only
abstract java.lang.Iterable<EntityInfo>	listDirectory(java.lang.String path) Reads a given directory and returns an iterator.
java.lang.Iterable<ExtendedAttribute>	listExtendedAttributes(java.lang.String path) Lists the extended attributes of a path.
void	lockFile(FileHandle handle, long byteOffset, long length) Locks a file in the specified range for every write access except for the File Handle handle.
abstract FileHandle	openFile(java.lang.String file, boolean read, boolean write) Opens a file.
boolean	pathExists(java.lang.String path) Checks whether the path already exists.
abstract int	read(FileHandle handle, java.nio.ByteBuffer buffer, long offset) Reads from a file.
void	removeExtendedAttribute(java.lang.String path, java.lang.String attributeName) Sets or adds extended attributes.
abstract void	rename(java.lang.String source, java.lang.String destination) Renames a file/directory/symbolic link.
abstract void	setCreationTime(java.lang.String path, long ctime) Sets the creation time (unix timestamp).
void	setExtendedAttribute(java.lang.String path, ExtendedAttribute attribute) Sets or adds extended attribute.
abstract void	setLastAccessTime(java.lang.String path, long atime) Sets the last access time (unix timestamp).
abstract void	setLastModificationTime(java.lang.String path, long mtime) Sets the last modification time (unix timestamp).
abstract void	setLength(FileHandle handle, long length) Truncates or lengthens a file.
void	setUnixPermissions(java.lang.String path, UnixPermissions perms) Sets the unix permissions for a file/directory.
void	setWindowsAttributes(java.lang.String path, WindowsAttributes windowsAttributes) Sets the windows attributes.
boolean	supportsUnicodeFilenames() Returns true if the file system supports unicode filenames.
void	unlockFile(FileHandle handle, long byteOffset, long length) Unlocks a file in the specified range.
abstract void	write(FileHandle handle, java.nio.ByteBuffer buffer, long offset) (Over-)writes the buffer into the specified file handle.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FileSystem

public FileSystem()

Method Detail

listDirectory

public abstract java.lang.Iterable<EntityInfo> listDirectory(java.lang.String path)
                                                      throws NotADirectoryException,
                                                             PathNotFoundException,
                                                             AccessDeniedException

Reads a given directory and returns an iterator.

Parameters:

path - the path

Returns:

the iterator

Throws:

NotADirectoryException - the path is not a directory

PathNotFoundException - the path could not be found

AccessDeniedException - the access is denied

getFileMetaData

public abstract EntityInfo getFileMetaData(java.lang.String path)
                                    throws PathNotFoundException

Returns some meta data about the path.

Parameters:

path - the path

Returns:

the meta data

Throws:

PathNotFoundException - the path could not be found

rename

public abstract void rename(java.lang.String source,
          java.lang.String destination)
                     throws PathNotFoundException,
                            DestinationAlreadyExistsException,
                            AccessDeniedException

Renames a file/directory/symbolic link.
It is equivalent to moving a file/directory.

Parameters:

source - the source path

destination - the destination path

Throws:

PathNotFoundException - the source path or the parent directory of the destination could not be found

DestinationAlreadyExistsException - the destination already exists

AccessDeniedException - the access is denied

openFile

public abstract FileHandle openFile(java.lang.String file,
                  boolean read,
                  boolean write)
                             throws PathNotFoundException,
                                    AccessDeniedException,
                                    NotAFileException

Opens a file.
It is guaranteed that createFile is called first for new files.
You should not overwrite the file if write is true.

Parameters:

file - the file to open

read - whether the file should be open to read

write - whether the file should be open to write

Returns:

the file handle

Throws:

PathNotFoundException - the file was not found

AccessDeniedException - the access is denied

NotAFileException - the given path is not a file

createFile

public abstract void createFile(java.lang.String path)
                         throws PathNotFoundException,
                                DestinationAlreadyExistsException,
                                AccessDeniedException

Creates a new (blank) file.

Parameters:

path - the path to the file

Throws:

PathNotFoundException - the parent directory could not be found

DestinationAlreadyExistsException - the destination already exists (regardless whether it is a directory or a file)

AccessDeniedException - the access is denied

createDirectory

public abstract void createDirectory(java.lang.String path)
                              throws PathNotFoundException,
                                     DestinationAlreadyExistsException,
                                     AccessDeniedException

Creates a new, empty directory.

Parameters:

path - the path to the new directory

Throws:

PathNotFoundException - the parent directory could not be found

DestinationAlreadyExistsException - the destination already exists (regardless whether it is a directory or a file)

AccessDeniedException - the access is denied

read

public abstract int read(FileHandle handle,
       java.nio.ByteBuffer buffer,
       long offset)

Reads from a file.
Offset specifies the offset within the opened file, not within the buffer.
The handle is guaranteed to be a valid file handle.

Parameters:

handle - the file handle

buffer - the buffer to fill

offset - the offset within the file

Returns:

the number of read bytes

setLength

public abstract void setLength(FileHandle handle,
             long length)
                        throws DriveFullException

Truncates or lengthens a file.
The handle is guaranteed to be a valid file handle.

Parameters:

handle - the file handle

length - the new file size in bytes

Throws:

DriveFullException - there is no more space

write

public abstract void write(FileHandle handle,
         java.nio.ByteBuffer buffer,
         long offset)
                    throws DriveFullException,
                           PartIsLockedException

(Over-)writes the buffer into the specified file handle.
Offset specifies the offset within the opened file, not within the buffer.
The handle is guaranteed to be a valid file handle.

Be careful: offset may be larger than the file size!
In this case you should fill everything in between with zeros.

Parameters:

handle - the file handle.

buffer - the buffer to write

offset - the offset within the file

Throws:

DriveFullException - there is no more space

PartIsLockedException - the specified range has been locked

flush

public abstract void flush(FileHandle handle)
                    throws DriveFullException

Should write all pending data in the cache.
It is not guaranteed that this method is called before close.
The handle is guaranteed to be a valid file handle.

Parameters:

handle - the file handle

Throws:

DriveFullException - there is no more free space

close

public abstract void close(FileHandle handle)
                    throws DriveFullException

Closes the file handle.
The handle is guaranteed to be a valid file handle and not closed yet.

Parameters:

handle - the file handle

Throws:

DriveFullException - there is no more space

deleteFile

public abstract void deleteFile(java.lang.String file)
                         throws PathNotFoundException,
                                AccessDeniedException

Deletes a file or symbolic link.

Parameters:

file - the file

Throws:

PathNotFoundException - the file could not be found

AccessDeniedException - the access is denied

NotAFileException - the specified path is not a file

deleteDirectoryRecursively

public abstract void deleteDirectoryRecursively(java.lang.String directory)
                                         throws PathNotFoundException,
                                                AccessDeniedException

Deletes a directory recursively.

Parameters:

directory - the directory

Throws:

PathNotFoundException - the directory could not be found

AccessDeniedException - the access is denied

getVolumeName

public abstract java.lang.String getVolumeName()

Returns the volume name.

Returns:

the volume name

getFileSystemName

public abstract java.lang.String getFileSystemName()

Returns the file system name

Returns:

the file system name

setLastAccessTime

public abstract void setLastAccessTime(java.lang.String path,
                     long atime)
                                throws PathNotFoundException,
                                       AccessDeniedException

Sets the last access time (unix timestamp).

Parameters:

path - the path

atime - the last access time (unix timestamp)

Throws:

PathNotFoundException - the path could not be found.

AccessDeniedException - the access is denied

setLastModificationTime

public abstract void setLastModificationTime(java.lang.String path,
                           long mtime)
                                      throws PathNotFoundException,
                                             AccessDeniedException

Sets the last modification time (unix timestamp).

Parameters:

path - the path

mtime - the last modification time (unix timestamp)

Throws:

PathNotFoundException - the path could not be found.

AccessDeniedException - the access is denied

setCreationTime

public abstract void setCreationTime(java.lang.String path,
                   long ctime)
                              throws PathNotFoundException,
                                     AccessDeniedException

Sets the creation time (unix timestamp).

Parameters:

path - the path

ctime - the creation time (unix timestamp)

Throws:

PathNotFoundException - the path could not be found.

AccessDeniedException - the access is denied

isCaseSensitive

public abstract boolean isCaseSensitive()

Returns true if the pathes are case sensitive

Returns:

true if the pathes are case sensitive

getBlockSize

public abstract int getBlockSize()

Returns the block size in bytes

Returns:

the block size

getTotalBlockCount

public abstract long getTotalBlockCount()

Returns the number of total blocks. E.g. a virtual 40 mb hard drive with 1 mb block size has 40 total blocks.

Returns:

the number of total blocks

getFreeBlockAvailableCount

public abstract long getFreeBlockAvailableCount()

Returns the number of free blocks, which are available to the current user.
In the easiast case:
Available Free Block Count = Free Block Count

Returns:

the number of free blocks

getFreeBlockCount

public abstract long getFreeBlockCount()

Returns the number of free blocks.

Returns:

the number of free blocks

getMountPath

public java.lang.String getMountPath()

Returns the mount path

Returns:

the mount path

createSymbolicLink

public void createSymbolicLink(java.lang.String source,
                      java.lang.String destination)
                        throws PathNotFoundException,
                               SourceAlreadyExistsException,
                               AccessDeniedException,
                               UnsupportedFeatureException

Creates a symbolic link at source pointing to destination.
The default file system does not support this feature.

Parameters:

source - the source

destination - the destination

Throws:

PathNotFoundException - the parent directory (of source) could not be found

SourceAlreadyExistsException - the source does already exist

AccessDeniedException - the access was denied

UnsupportedFeatureException - the feature is unsupported

See Also:

https://en.wikipedia.org/wiki/Symbolic_link

createHardLink

public void createHardLink(java.lang.String source,
                  java.lang.String destination)
                    throws PathNotFoundException,
                           SourceAlreadyExistsException,
                           AccessDeniedException,
                           UnsupportedFeatureException

Creates a hard link at source pointing to destination.
The default file system does not support this feature.

Parameters:

source - the source

destination - the destination

Throws:

PathNotFoundException - the parent directory could not be found

SourceAlreadyExistsException - the source does already exist

AccessDeniedException - the access was denied

UnsupportedFeatureException - the feature is unsupported

See Also:

https://en.wikipedia.org/wiki/Hard_link

pathExists

public boolean pathExists(java.lang.String path)

Checks whether the path already exists.
This is done via calling getFileMetaData and catching the PathNotFoundException.
You should consider to override it with a faster implementation

Parameters:

path - the path

Returns:

true if path exists

getMaxPathLength

public int getMaxPathLength()

Returns the maximum path length. The default value is 32768.

Returns:

the maximum path length

getFilesFreeCount

public int getFilesFreeCount()

Returns the number of files which may be created.

Returns:

the number of files which may be created

getTotalFilesCount

public int getTotalFilesCount()

Returns the total number of files on the volume.
By default it returns 0, but it does not seem to harmful.

Returns:

the total number of files

setUnixPermissions

public void setUnixPermissions(java.lang.String path,
                      UnixPermissions perms)
                        throws PathNotFoundException,
                               AccessDeniedException,
                               UnsupportedFeatureException

Sets the unix permissions for a file/directory.
This feature is not supported by default.

Parameters:

path - the path

perms - the permissions

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

UnsupportedFeatureException - the feature is unsupported

getUnixPermissions

public UnixPermissions getUnixPermissions(java.lang.String path)
                                   throws PathNotFoundException

Returns the unix permissions

Parameters:

path - the path

Returns:

the permissions

Throws:

PathNotFoundException - the path was not found

setWindowsAttributes

public void setWindowsAttributes(java.lang.String path,
                        WindowsAttributes windowsAttributes)
                          throws PathNotFoundException,
                                 AccessDeniedException,
                                 UnsupportedFeatureException

Sets the windows attributes.
This feature is not supported by default.

Parameters:

path - the path

windowsAttributes - the windows attributes

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

UnsupportedFeatureException - the feature is not supported

getWindowsAttributes

public WindowsAttributes getWindowsAttributes(java.lang.String path)
                                       throws PathNotFoundException,
                                              AccessDeniedException,
                                              UnsupportedFeatureException

Returns the windows attributes.
The default implementation:
If the file system is read only, it returns the read only attribute.
If not, it does not return any attribute.

Parameters:

path - the path

Returns:

the windows attributes

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

UnsupportedFeatureException - the feature is not supported

lockFile

public void lockFile(FileHandle handle,
            long byteOffset,
            long length)
              throws PathNotFoundException,
                     AccessDeniedException,
                     NotAFileException,
                     UnsupportedFeatureException,
                     AlreadyLockedException

Locks a file in the specified range for every write access except for the File Handle handle.
This is windows specific.
This feature is not supported by default.

Parameters:

handle - the file handle

byteOffset - the byte offset

length - the length

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

NotAFileException - the path is not a file

UnsupportedFeatureException - the feature is not supported

AlreadyLockedException - parts of the specified range are already locked

unlockFile

public void unlockFile(FileHandle handle,
              long byteOffset,
              long length)
                throws PathNotFoundException,
                       AccessDeniedException,
                       NotAFileException,
                       UnsupportedFeatureException

Unlocks a file in the specified range.
This is windows specific.
The caller does not perform a check that the file handle is identical to the locker's file handle.
This feature is not supported by default.

Parameters:

handle - the file handle

byteOffset - the byte offset

length - the length

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

NotAFileException - the path is not a file

UnsupportedFeatureException - the feature is not supported

getNumberOfFilesInDirectory

public int getNumberOfFilesInDirectory(DirectoryInfo info)

Returns the number of files (and direct subdirectories) in a directory

Parameters:

info - the directory info

Returns:

the number of files

delete

public final void delete(java.lang.String path)
                  throws PathNotFoundException,
                         AccessDeniedException

Checks whether path is a file or directory and calls the appropriate method

Parameters:

path - the path

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

supportsUnicodeFilenames

public boolean supportsUnicodeFilenames()

Returns true if the file system supports unicode filenames.
Since most file systems use Java Strings to encode file names, the default value is true.

Returns:

true if the file system supports unicode filenames.

isCompressed

public boolean isCompressed()

Returns true if the file system is compressed

Returns:

true if the file system is compressed

getVolumeSerialNumber

public int getVolumeSerialNumber()

Returns a volume serial number

Returns:

a volume serial number

isReadOnly

public boolean isReadOnly()

Returns true if the file system is read only

Returns:

true if the file system is read only

getExtendedAttribute

public ExtendedAttribute getExtendedAttribute(java.lang.String path,
                                     java.lang.String name)
                                       throws PathNotFoundException,
                                              AccessDeniedException,
                                              UnsupportedFeatureException,
                                              AttributeNotFoundException

Returns one specific extended attribute.
This method does not need to be overriden.

Parameters:

path - the path of the file

name - the name of the attribute

Returns:

the attribute

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

UnsupportedFeatureException - the feature is not supported

AttributeNotFoundException - the specified attribute was not found

listExtendedAttributes

public java.lang.Iterable<ExtendedAttribute> listExtendedAttributes(java.lang.String path)
                                                             throws PathNotFoundException,
                                                                    AccessDeniedException,
                                                                    UnsupportedFeatureException

Lists the extended attributes of a path.
This feature is not supported by default.

Parameters:

path - the path

Returns:

the extended attributes

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

UnsupportedFeatureException - the feature is not supported

setExtendedAttribute

public void setExtendedAttribute(java.lang.String path,
                        ExtendedAttribute attribute)
                          throws PathNotFoundException,
                                 AccessDeniedException,
                                 UnsupportedFeatureException

Sets or adds extended attribute.
This feature is not supported by default.

Parameters:

path - the path

attribute - the attribute to add/set

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

UnsupportedFeatureException - the feature is not supported

removeExtendedAttribute

public void removeExtendedAttribute(java.lang.String path,
                           java.lang.String attributeName)
                             throws PathNotFoundException,
                                    AccessDeniedException,
                                    UnsupportedFeatureException,
                                    AttributeNotFoundException

Sets or adds extended attributes.
This feature is not supported by default.

Parameters:

path - the path

attributeName - the attribute name

Throws:

PathNotFoundException - the path was not found

AccessDeniedException - the access is denied

UnsupportedFeatureException - the feature is not supported

AttributeNotFoundException - the specified attribute was not found

beforeMounting

public void beforeMounting(java.lang.String mountPath)

Is called directly before the file system is mounted

Parameters:

mountPath - the mount path

beforeUnmounting

public void beforeUnmounting()

Is called directly before the file system is unmounted

afterUnmounting

public void afterUnmounting()

Is called after the file system has been unmounted successfully.