org.joe_e.file
Class Filesystem

java.lang.Object
  org.joe_e.file.Filesystem

public final class Filesystem
extends java.lang.Object

File construction. This provides a capability-safe API for access to files. A File object grants read and write access to a file or directory. Due to limitations in Java, all file references are to textual file names, not file descriptors. Multiple operations on a File may thus apply to different incarnations of the file.

Method Summary

static void	checkName(java.lang.String name) Vets a filename.
static java.io.File	file(java.io.File folder, java.lang.String child) Produce a File capability for a file contained in a folder.
static long	length(java.io.File file) Gets the length of a file
static ConstArray<java.io.File>	list(java.io.File dir) List the contents of a directory.
static java.io.InputStream	read(java.io.File file) Opens an existing file for reading.
static java.io.OutputStream	writeNew(java.io.File file) Creates a file for writing.

Methods inherited from class java.lang.Object

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

Method Detail

file

public static java.io.File file(java.io.File folder,
                                java.lang.String child)
                         throws InvalidFilenameException

Produce a File capability for a file contained in a folder. The returned object is just a handle; the underlying file may not yet exist.

Parameters:

folder - containing folder

child - a single filename component, not a relative path

Returns:

a capability for the requested file

Throws:

java.lang.IllegalArgumentException - if folder is null or the empty path

InvalidFilenameException

checkName

public static void checkName(java.lang.String name)
                      throws InvalidFilenameException

Vets a filename. Checks that the argument would be interpreted as a file name rather than as a path or relative directory specifier

Parameters:

name - a single filename component, not a relative path

Throws:

InvalidFilenameException - name is rejected\

list

public static ConstArray<java.io.File> list(java.io.File dir)
                                     throws java.io.IOException

List the contents of a directory.

Parameters:

dir - directory to list

Returns:

directory entries, sorted alphabetically

Throws:

java.io.IOException - dir is not a directory, or an I/O error

length

public static long length(java.io.File file)
                   throws java.io.FileNotFoundException

Gets the length of a file

Parameters:

file - file to stat

Returns:

the length of the file in bytes

Throws:

java.io.FileNotFoundException - file not found

read

public static java.io.InputStream read(java.io.File file)
                                throws java.io.FileNotFoundException

Opens an existing file for reading.

Parameters:

file - file to open

Returns:

opened input stream

Throws:

java.io.FileNotFoundException - file not found

writeNew

public static java.io.OutputStream writeNew(java.io.File file)
                                     throws java.io.IOException

Creates a file for writing.

Parameters:

file - file to create

Returns:

opened output stream

Throws:

java.io.IOException - file could not be created