net.sf.basedb.util
Class FileUtil

java.lang.Object
  net.sf.basedb.util.FileUtil

public class FileUtil
extends Object

This class collects some useful methods for file and stream handling.

Version:

2.0

Author:

Nicklas

Last modified

$Date$

Field Summary

private static int

BUFFER_SIZE

Constructor Summary

FileUtil()

Method Summary

static boolean	checkMagicNumber(PushbackInputStream pin, byte[] bCheck) Take a peek at an input stream and check if the first few bytes matches the bCheck parameter.
static void	close(InputStream in) Close an input stream without throwing an exception.
static void	close(OutputStream out) Close an output stream without throwing an exception.
static long	copy(InputStream in, OutputStream out) Copy from the input stream to the output stream until end of file is reached.
static long	copy(InputStream in, OutputStream out, AbsoluteProgressReporter progress) Copy from the input stream to the output stream until end of file is reached.
static long	copy(Reader in, Writer out) Copy from the reader to the writer until end of file is reached.
static long	copy(Reader in, Writer out, AbsoluteProgressReporter progress) Copy from the reader to the writer until end of file is reached.
static File	createTempDirectory(String prefix, String suffix, File directory) Creates a temporary directory.
static int	deleteEmptyDirectories(File root, boolean deleteRoot) Deletes all empty subdirectories and, optionally, also the root directory.
static int	deleteTempDirectory(File root) Recursively delete all files and subdirectories within a given directory and the also the given directory itself.
static void	doRecursively(DbControl dc, Directory root, Filter<? super Directory> dirFilter, Filter<? super File> fileFilter) Do something recursively to all files and sub-directories in specified root directory.
static List<File>	findFiles(File directory, FileFilter filter) Find files matching a given filter in a directory.
static Map<Directory,List<Directory>>	getDirectoryTree(DbControl dc, Directory directory) Get the complete tree of sub-directories from a given directory.
static InputStream	getInputStream(File file) Get a buffered InputStream object reading from the specified file.
static OutputStream	getOutputStream(File file) Get a buffered OutputStream object writing to the specified file.
static Map<Directory,List<Directory>>	loadMinimalDirectoryTree(DbControl dc, Directory... directories) Load a minimal directory tree that includes at least all the specified directories and their parent directories all the way up to the root or as far as the logged in user has read permission.
static long	read(InputStream in) Read from the input stream until the end is reached.
static List<File>	uploadFiles(DbControl dc, Directory toDir, File fromDir, FileFilter filter, boolean overwrite, ProgressReporter progress) Upload multiple files to BASE.

Methods inherited from class java.lang.Object

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

Field Detail

BUFFER_SIZE

private static final int BUFFER_SIZE

See Also:

Constant Field Values

Constructor Detail

FileUtil

public FileUtil()

Method Detail

copy

public static long copy(InputStream in,
                        OutputStream out)
                 throws IOException

Copy from the input stream to the output stream until end of file is reached.

Parameters:

in - The InputStream to read from

out - The OutputStream to write to

Returns:

The number of bytes copied

Throws:

IOException - This exception is thrown if there is an error

copy

public static long copy(InputStream in,
                        OutputStream out,
                        AbsoluteProgressReporter progress)
                 throws IOException

Copy from the input stream to the output stream until end of file is reached.

Parameters:

in - The InputStream to read from

out - The OutputStream to write to

progress - An optional progress reporter

Returns:

The number of bytes copied

Throws:

IOException - This exception is thrown if there is an error

Since:

2.5

copy

public static long copy(Reader in,
                        Writer out)
                 throws IOException

Copy from the reader to the writer until end of file is reached.

Parameters:

in - The Reader to read from

out - The Writer to write to

Returns:

The number of characters copied

Throws:

IOException - This exception is thrown if there is an error

Since:

2.12

copy

public static long copy(Reader in,
                        Writer out,
                        AbsoluteProgressReporter progress)
                 throws IOException

Copy from the reader to the writer until end of file is reached.

Parameters:

in - The Reader to read from

out - The Writer to write to

progress - An optional progress reporter

Returns:

The number of characters copied

Throws:

IOException - This exception is thrown if there is an error

Since:

2.12

read

public static long read(InputStream in)
                 throws IOException

Read from the input stream until the end is reached.

Parameters:

in - The InputStream to read from

Returns:

The number of bytes copied

Throws:

IOException - This exception is thrown if there is an error

Since:

2.4

close

public static void close(InputStream in)

Close an input stream without throwing an exception.

Parameters:

in - The input stream to close

Since:

2.9

close

public static void close(OutputStream out)

Close an output stream without throwing an exception.

Parameters:

out - The output stream to close

Since:

2.9

getInputStream

public static InputStream getInputStream(File file)
                                  throws IOException

Get a buffered InputStream object reading from the specified file.

Parameters:

file - The path to the file to read from

Returns:

A buffered InputStream

Throws:

IOException - If the stream cannot be opened

getOutputStream

public static OutputStream getOutputStream(File file)
                                    throws IOException

Get a buffered OutputStream object writing to the specified file.

Parameters:

file - The path to the file to write to

Returns:

A buffered OutputStream

Throws:

IOException - If the stream cannot be opened

checkMagicNumber

public static boolean checkMagicNumber(PushbackInputStream pin,
                                       byte[] bCheck)
                                throws IOException

Take a peek at an input stream and check if the first few bytes matches the bCheck parameter. After the check the bytes are pushed back to the stream again. This method is useful to check the file format of a file, which can often be done by checing the first few bytes at the start of the file. For example to check if the file is gzip file:

bCheck = new byte[] { 0x1f, (byte)0x8b };

Parameters:

pin - The input stream to read from which must have large enough buffer to be able to unread the bytes

bCheck - The byte values to use for comparison

Returns:

TRUE if the file matches the specified bytes, FALSE otherwise

Throws:

IOException - If there is an error reading or unreading the bytes

NullPointerException - If pin or bCheck is null

IllegalArgumentException - If bCheck is zero length

Since:

2.4

getDirectoryTree

public static Map<Directory,List<Directory>> getDirectoryTree(DbControl dc,
                                                              Directory directory)
                                                       throws InvalidDataException,
                                                              BaseException

Get the complete tree of sub-directories from a given directory.

NOTE!!! This method has very bad performance on large directory trees. Consider if it is not possible to use the loadMinimalDirectoryTree(DbControl, Directory...) instead together with lazy loading of subdirectories.

Parameters:

dc - DbControl used to access the database.

directory - The directory to start with

Returns:

A Map which maps a directory to a list of it's sub-directories. Directories without sub-directories are not included in the map.

Throws:

InvalidDataException - If the directory is null

BaseException - If there is another error

loadMinimalDirectoryTree

public static Map<Directory,List<Directory>> loadMinimalDirectoryTree(DbControl dc,
                                                                      Directory... directories)
                                                               throws InvalidDataException,
                                                                      BaseException

Load a minimal directory tree that includes at least all the specified directories and their parent directories all the way up to the root or as far as the logged in user has read permission.

Parameters:

dc - A DbControl for accessing the database

directories - An array of directories

Returns:

A Map which maps a directory to a list of it's sub-directories. The map is guaranteed to contain an entry for each of the given directories, but the list may be empty if there are no subdirectories

Throws:

BaseException - If there is an error

InvalidDataException

Since:

2.11

findFiles

public static List<File> findFiles(File directory,
                                   FileFilter filter)

Find files matching a given filter in a directory. If the filter returns sub-directories, this method will check those directories too. Use, for example, the RegexpFileFilter to look for files matching a regular expression.

Parameters:

directory - The parent directory to search in

filter - A filter which specifies which files to find, or null to find all files

Returns:

A List with the files in directory that matches the filter, or null if the specified directory doesn't exists or isn't a directory

Since:

2.5

See Also:

RegexpFileFilter

deleteEmptyDirectories

public static int deleteEmptyDirectories(File root,
                                         boolean deleteRoot)

Deletes all empty subdirectories and, optionally, also the root directory.

Parameters:

root - The root directory to start looking in

deleteRoot - TRUE to also delete the root directory if it is empty, FALSE to leave it

Returns:

The number of deleted directories

Since:

2.13

doRecursively

public static void doRecursively(DbControl dc,
                                 Directory root,
                                 Filter<? super Directory> dirFilter,
                                 Filter<? super File> fileFilter)

Do something recursively to all files and sub-directories in specified root directory. If no directory filter is specified, all subdirectories are processed, otherwise only those directories were the Filter.evaluate(Object) method returns TRUE.

Files are only loaded if a file filter is specified. The return value of the evaluate method is ignored.

The files and directories may be processed in any order.

NOTE! The intention of this method is that the filter should have have a "side-effect" that does some work on the files/ sub-directories.

Parameters:

dc - A DbControl to use for database access

root - The root directory

dirFilter - A filter that selects/rejects sub-directories

fileFilter - A filter that does something with the file

Since:

2.13

createTempDirectory

public static File createTempDirectory(String prefix,
                                       String suffix,
                                       File directory)
                                throws IOException

Creates a temporary directory. This method uses the built-in File.createTempFile(String, String, File) method to first crete a temporary file, that is then deleted and made into a directory instead. This should ensure that a new empty directory is created each time this method is called. The "temporary" nature of this method doesn't involve cleaning up or removing the created directory. It is the responsibility of the calling code to remove every file and subdirectory as well as the returned directory. This can for example be done with the deleteTempDirectory(File) method.

Parameters:

prefix - A prefix that is used in the directory name it must be at least 3 characters long.

suffix - An optional suffix for the directory name

directory - An optional parent directory in which the temporary directory should be created, or null to use the system temporary directory

Returns:

A reference to the created directory

Throws:

IOException - If there is a problem with the directory creation

Since:

2.15

See Also:

File.createTempFile(String, String, File)

deleteTempDirectory

public static int deleteTempDirectory(File root)

Recursively delete all files and subdirectories within a given directory and the also the given directory itself.

Parameters:

root - The root directory to start looking in

Returns:

The number of deleted files and directories

Since:

2.15

uploadFiles

public static List<File> uploadFiles(DbControl dc,
                                     Directory toDir,
                                     File fromDir,
                                     FileFilter filter,
                                     boolean overwrite,
                                     ProgressReporter progress)
                              throws IOException

Upload multiple files to BASE.

Parameters:

toDir - The directory in the BASE file system that the files should be uploaded to

fromDir - The directory in the local file system to scan for files to upload if the directory doesn't exists or is empty an empty list is returned

filter - An optional filter that decides which files that should be uploaded or not, if null all files, including subdirectories, are uploaded

overwrite - TRUE if existing files should be overwritten, FALSE to only overwrite files that have been marked for removal

progress - An optional progress reporter

Returns:

A list with the new file items that were created

Throws:

IOException

Since:

2.16