Package org.wikidata.wdtk.util

Interface DirectoryManager

All Known Implementing Classes:

DirectoryManagerImpl

public interface DirectoryManager

Interface for classes that read and write files from one directory. Allows for mock implementations to test functionality without actually writing files.

Author:

Markus Kroetzsch

Method Summary

Modifier and Type	Method	Description
long	createFile(String fileName, InputStream inputStream)	Creates a new file in the current directory, and fill it with the data from the given input stream.
void	createFile(String fileName, String fileContents)	Creates a new file in the current directory, and fill it with the given data, encoded in UTF-8.
long	createFileAtomic(String fileName, InputStream inputStream)	Creates a new file in the current directory, and fill it with the data from the given input stream.
InputStream	getInputStreamForFile(String fileName, CompressionType compressionType)	Returns an input stream to access file of the given name within the current directory, possibly uncompressing it if required.
OutputStream	getOutputStreamForFile(String fileName)	Opens and returns an output stream that can be used to write to the file of the given name within the current directory.
List<String>	getSubdirectories(String glob)	Returns a list of the names of all subdirectories of the base directory.
DirectoryManager	getSubdirectoryManager(String subdirectoryName)	Returns a new directory manager for the subdirectory of the given name.
boolean	hasFile(String fileName)	Checks if there is a file of the given name.
boolean	hasSubdirectory(String subdirectoryName)	Checks if there is a subdirectory of the given name.

Method Detail

getSubdirectoryManager

DirectoryManager getSubdirectoryManager(String subdirectoryName)
                                 throws IOException

Returns a new directory manager for the subdirectory of the given name. If the subdirectory does not exist yet, it will be created. If this is not desired, its existence can be checked with hasSubdirectory(String) first (ignoring the fact that there might be race conditions when accessing the file system).

Parameters:

subdirectoryName - the string name of the subdirectory

Returns:

DirectoryManager for subdirectory

Throws:

IOException - if directory could not be created

hasSubdirectory

boolean hasSubdirectory(String subdirectoryName)

Checks if there is a subdirectory of the given name.

Parameters:

subdirectoryName - the name of the subdirectory

Returns:

true if the subdirectory exists

hasFile

boolean hasFile(String fileName)

Checks if there is a file of the given name.

Parameters:

fileName - the name of the file

Returns:

true if the file exists and is not a directory

createFile

long createFile(String fileName,
                InputStream inputStream)
         throws IOException

Creates a new file in the current directory, and fill it with the data from the given input stream. If the stream encodes a string, then it should generally be encoded in UTF-8, since access methods assume this.

Parameters:

fileName - the name of the file

inputStream - the input stream from which to load the file

Returns:

size of the new file in bytes

Throws:

IOException

createFileAtomic

long createFileAtomic(String fileName,
                      InputStream inputStream)
               throws IOException

Creates a new file in the current directory, and fill it with the data from the given input stream. This is done by first writing the data to a temporary file that uses a suffix to the file name, and then moving the completed file to the new location. This should be used when fetching larger files through from slow stream (e.g., a download) to prevent partially finished file downloads lying around if the program is terminated during download. The temporary file will still be lying around, but it will not be mistaken for the completed download by any other parts of the program.

If the stream encodes a string, then it should generally be encoded in UTF-8, since access methods assume this.

Parameters:

fileName - the name of the file

inputStream - the input stream from which to load the file

Returns:

size of the new file in bytes

Throws:

IOException

createFile

void createFile(String fileName,
                String fileContents)
         throws IOException

Creates a new file in the current directory, and fill it with the given data, encoded in UTF-8. Should only be used for short pieces of data.

Parameters:

fileName - the name of the file

fileContents - the data to write into the file

Throws:

IOException

getOutputStreamForFile

OutputStream getOutputStreamForFile(String fileName)
                             throws IOException

Opens and returns an output stream that can be used to write to the file of the given name within the current directory. The stream is owned by the caller and must be closed after use. If the file already exists, it will be truncated at this operation.

Parameters:

fileName - the name of the file

Returns:

the stream to write to

Throws:

IOException

getInputStreamForFile

InputStream getInputStreamForFile(String fileName,
                                  CompressionType compressionType)
                           throws IOException

Returns an input stream to access file of the given name within the current directory, possibly uncompressing it if required.

It is important to close the stream after using it to free memory.

Parameters:

fileName - the name of the file

compressionType - for types other than CompressionType.NONE, the file will be uncompressed appropriately and the returned input stream will provide access to the uncompressed content

Returns:

an InputStream to fetch data from the file

Throws:

IOException

getSubdirectories

List<String> getSubdirectories(String glob)
                        throws IOException

Returns a list of the names of all subdirectories of the base directory. The glob pattern can be used to filter the names; "*" should be used if no filtering is desired.

Parameters:

glob - pattern to filter directoy names

Returns:

list of subdirectory names

Throws:

IOException