ca.uqac.lif.fs

Class FilterFileSystem

java.lang.Object

ca.uqac.lif.fs.FilterFileSystem

All Implemented Interfaces:

FileSystem

Direct Known Subclasses:

Base64FileSystem, Chroot, ReadOnlyFileSystem, ThrottledFileSystem

public class FilterFileSystem
extends java.lang.Object
implements FileSystem

A file system that delegates all its operations to another file system passed as a parameter. The class FilterFileSystem itself simply overrides all methods of FileSystem with versions that pass all requests to the contained file system. Subclasses of FilterFileSystem may further override some of these methods and may also provide additional methods and fields.

Author:

Sylvain Hallé

Nested Class Summary

Nested classes/interfaces inherited from interface ca.uqac.lif.fs.FileSystem

FileSystem.OpenState

Field Summary

Fields

Modifier and Type	Field and Description
protected FileSystem	m_fs The file system to which operations are delegated.

Constructor Summary

Constructors

Constructor and Description
FilterFileSystem(FileSystem fs) Creates a new filter file system.

Method Summary

Modifier and Type	Method and Description
void	chdir(java.lang.String path) Changes the current directory.
void	close() Stops the interaction with the file system.
void	delete(java.lang.String path) Deletes a directory and all its contents.
long	getSize(java.lang.String path) Gets the size of a file.
boolean	isDirectory(java.lang.String path) Determines if the resource pointed to by a given path corresponds to a directory.
boolean	isFile(java.lang.String path) Determines if the resource pointed to by a given path corresponds to a file.
java.util.List<java.lang.String>	ls() Lists all the files and folders in the current directory.
java.util.List<java.lang.String>	ls(java.lang.String path) Lists all the files and folders in a given directory.
void	mkdir(java.lang.String path) Creates a directory if it does not exist.
void	open() Starts the interaction with the file system.
void	popd() Changes the current directory to the one before the last call to FileSystem.chdir(String) or FileSystem.pushd(String).
void	pushd(java.lang.String path)
java.lang.String	pwd() Retrieves the current working directory, relative to the root of the file system.
java.io.InputStream	readFrom(java.lang.String filename) Reads data from a file.
void	rmdir(java.lang.String path) Deletes a directory and all its contents.
java.io.OutputStream	writeTo(java.lang.String filename) Writes data to a file.

Methods inherited from class java.lang.Object

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

Field Detail

m_fs

protected final FileSystem m_fs

The file system to which operations are delegated.

Constructor Detail

FilterFileSystem

public FilterFileSystem(FileSystem fs)

Creates a new filter file system.

Parameters:

fs - The file system to which operations are delegated

Method Detail

open

public void open()
          throws FileSystemException

Description copied from interface: FileSystem

Starts the interaction with the file system. All operations invoked on a file system will throw a FileSystemException if called before this method.

Specified by:

open in interface FileSystem

Throws:

FileSystemException - Thrown if the interaction with the file system cannot be started

getSize

public long getSize(java.lang.String path)
             throws FileSystemException

Description copied from interface: FileSystem

Gets the size of a file.

Specified by:

getSize in interface FileSystem

Parameters:

path - The path corresponding to the file

Returns:

The size in bytes

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

ls

public java.util.List<java.lang.String> ls()
                                    throws FileSystemException

Description copied from interface: FileSystem

Lists all the files and folders in the current directory.

Specified by:

ls in interface FileSystem

Returns:

The list of files and folders

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

ls

public java.util.List<java.lang.String> ls(java.lang.String path)
                                    throws FileSystemException

Description copied from interface: FileSystem

Lists all the files and folders in a given directory.

Specified by:

ls in interface FileSystem

Parameters:

path - The path from which to list files

Returns:

The list of files and folders

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

isDirectory

public boolean isDirectory(java.lang.String path)
                    throws FileSystemException

Description copied from interface: FileSystem

Determines if the resource pointed to by a given path corresponds to a directory.

Specified by:

isDirectory in interface FileSystem

Parameters:

path - The path

Returns:

true if the resource exists and is a directory, false otherwise

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

isFile

public boolean isFile(java.lang.String path)
               throws FileSystemException

Description copied from interface: FileSystem

Determines if the resource pointed to by a given path corresponds to a file.

Specified by:

isFile in interface FileSystem

Parameters:

path - The path

Returns:

true if the resource exists and is a file, false otherwise

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

writeTo

public java.io.OutputStream writeTo(java.lang.String filename)
                             throws FileSystemException

Description copied from interface: FileSystem

Writes data to a file. The method provides an OutputStream to which data can be printed. The data is guaranteed to be committed to the file only when the print stream is closed. Whether data is written before that moment depends on the actual file system implementation.

Specified by:

writeTo in interface FileSystem

Parameters:

filename - The name of the file to which data is to be written

Returns:

An output stream open on the file. If the method successfully returns, it guarantees that this stream is not null

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

readFrom

public java.io.InputStream readFrom(java.lang.String filename)
                             throws FileSystemException

Description copied from interface: FileSystem

Reads data from a file. The method provides an InputStream from which data can be read. Consumers of this input stream have the responsibility to close the stream after usage.

Specified by:

readFrom in interface FileSystem

Parameters:

filename - The name of the file to which data is to be written

Returns:

A print stream open on the file. If the method successfully returns, it guarantees that this stream is not null

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

chdir

public void chdir(java.lang.String path)
           throws FileSystemException

Description copied from interface: FileSystem

Changes the current directory.

Specified by:

chdir in interface FileSystem

Parameters:

path - The directory to change to. The string can contain a path relative to the current directory.

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

pushd

public void pushd(java.lang.String path)
           throws FileSystemException

Specified by:

pushd in interface FileSystem

Parameters:

path - The directory to change to. The string can contain a path relative to the current directory.

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

popd

public void popd()
          throws FileSystemException

Description copied from interface: FileSystem

Changes the current directory to the one before the last call to FileSystem.chdir(String) or FileSystem.pushd(String).

Specified by:

popd in interface FileSystem

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

mkdir

public void mkdir(java.lang.String path)
           throws FileSystemException

Description copied from interface: FileSystem

Creates a directory if it does not exist.

Specified by:

mkdir in interface FileSystem

Parameters:

path - The directory to create. The string can contain a path relative to the current directory.

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

rmdir

public void rmdir(java.lang.String path)
           throws FileSystemException

Description copied from interface: FileSystem

Deletes a directory and all its contents.

Specified by:

rmdir in interface FileSystem

Parameters:

path - The directory to delete

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

delete

public void delete(java.lang.String path)
            throws FileSystemException

Description copied from interface: FileSystem

Deletes a directory and all its contents.

Specified by:

delete in interface FileSystem

Parameters:

path - The directory to delete

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

pwd

public java.lang.String pwd()
                     throws FileSystemException

Description copied from interface: FileSystem

Retrieves the current working directory, relative to the root of the file system.

Specified by:

pwd in interface FileSystem

Returns:

A string representing the current working directory

Throws:

FileSystemException - Thrown if the operation could not be performed for some reason

close

public void close()
           throws FileSystemException

Description copied from interface: FileSystem

Stops the interaction with the file system. All operations invoked on a file system will throw a FileSystemException if called after this method.

Specified by:

close in interface FileSystem

Throws:

FileSystemException - Thrown if an error occurred while stopping the interaction with the file system