org.grouplens.lenskit.util.io

Class LKFileUtils

java.lang.Object

org.grouplens.lenskit.util.io.LKFileUtils

public final class LKFileUtils
extends Object

File utilities for LensKit. Called LKFileUtils to avoid conflict with FileUtils classes that may be imported from other packages such as Guava, Plexus, or Commons.

Since:

0.10

Method Summary

Modifier and Type	Method and Description
static boolean	isCompressed(File file) Deprecated. Use CompressionMode or commons-compress facilities instead.
static Reader	openInput(File file) Open a reader with automatic compression and the default character set.
static Reader	openInput(File file, Charset charset, CompressionMode compression) Open a file for input, optionally compressed.
static Reader	openInput(File file, CompressionMode compression) Open a file for input with the default charset.
static Writer	openOutput(File file) Open a reader with automatic compression inference.
static Writer	openOutput(File file, Charset charset, CompressionMode compression) Open a file for input, optionally compressed.
static Writer	openOutput(File file, CompressionMode compression) Open a file for output with the default charset.
static LongList	readIdList(File file) Read a list of long IDs from a file, one per line.
static InputStream	transparentlyDecompress(InputStream stream) Auto-detect whether a stream needs decompression.

Methods inherited from class java.lang.Object

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

Method Detail

isCompressed

@Deprecated
public static boolean isCompressed(File file)

Deprecated. Use CompressionMode or commons-compress facilities instead.

Query whether this filename represents a compressed file. It just looks at the name to see if it ends in “.gz”.

Parameters:

file - The file to query.

Returns:

true if the file name ends in “.gz”.

openInput

public static Reader openInput(File file,
                               Charset charset,
                               CompressionMode compression)
                        throws IOException

Open a file for input, optionally compressed.

Parameters:

file - The file to open.

charset - The character set to use.

compression - Whether to compress the file.

Returns:

A reader opened on the file.

Throws:

IOException - if there is an error opening the file.

openInput

public static Reader openInput(File file,
                               CompressionMode compression)
                        throws IOException

Open a file for input with the default charset.

Parameters:

file - The file to open.

compression - The compression mode.

Returns:

A reader opened on the file.

Throws:

IOException - if there was an error opening the file.

See Also:

openInput(java.io.File, Charset, CompressionMode)

openInput

public static Reader openInput(File file)
                        throws IOException

Open a reader with automatic compression and the default character set.

Parameters:

file - The file to open.

Returns:

A reader opened on the input file.

Throws:

IOException - if there is an error opening the file.

See Also:

openInput(File, Charset, CompressionMode), CompressionMode.AUTO, Charset.defaultCharset()

openOutput

public static Writer openOutput(File file,
                                Charset charset,
                                CompressionMode compression)
                         throws IOException

Open a file for input, optionally compressed.

Parameters:

file - The file to open.

charset - The character set to use.

compression - Whether to compress the file.

Returns:

A reader opened on the file.

Throws:

IOException - if there is an error opening the file.

openOutput

public static Writer openOutput(File file,
                                CompressionMode compression)
                         throws IOException

Open a file for output with the default charset.

Parameters:

file - The file to open.

compression - The compression mode.

Returns:

A writer opened on the file.

Throws:

IOException - if there was an error opening the file.

See Also:

openInput(java.io.File, Charset, CompressionMode)

openOutput

public static Writer openOutput(File file)
                         throws IOException

Open a reader with automatic compression inference.

Parameters:

file - The file to open.

Returns:

A reader opened on the input file.

Throws:

IOException - if there is an error opening the file.

transparentlyDecompress

public static InputStream transparentlyDecompress(@WillCloseWhenClosed
                                                  InputStream stream)
                                           throws IOException

Auto-detect whether a stream needs decompression. Currently detects GZIP compression (using the GZIP magic in the header).

Parameters:

stream - The stream to read.

Returns:

A stream that will read from stream, decompressing if needed. It may not be the same object as stream, even if no decompression is needed, as the input stream may be wrapped in a buffered stream for lookahead.

Throws:

IOException

readIdList

public static LongList readIdList(File file)
                           throws IOException

Read a list of long IDs from a file, one per line.

Parameters:

file - The file to read.

Returns:

A list of longs.

Throws:

IOException