Package org.apache.lucene.index

Class IndexFileNames

java.lang.Object

org.apache.lucene.index.IndexFileNames

public final class IndexFileNames
extends Object

This class contains useful constants representing filenames and extensions used by lucene, as well as convenience methods for querying whether a file name matches an extension (matchesExtension), as well as generating file names from a segment name, generation and extension ( fileNameFromGeneration, segmentFileName).

NOTE: extensions used by codecs are not listed here. You must interact with the Codec directly.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Field Summary

Fields

Modifier and Type	Field	Description
static final Pattern	CODEC_FILE_PATTERN	All files created by codecs much match this pattern (checked in SegmentInfo).
static final String	PENDING_SEGMENTS	Name of pending index segment file
static final String	SEGMENTS	Name of the index segment file

Method Summary

Modifier and Type	Method	Description
static String	fileNameFromGeneration(String base, String ext, long gen)	Computes the full file name from base, extension and generation.
static String	getExtension(String filename)	Return the extension (anything after the first '.'), or null if there is no '.' in the file name.
static boolean	matchesExtension(String filename, String ext)	Returns true if the given filename ends with the given extension.
static long	parseGeneration(String filename)	Returns the generation from this file name, or 0 if there is no generation.
static String	parseSegmentName(String filename)	Parses the segment name out of the given file name.
static String	segmentFileName(String segmentName, String segmentSuffix, String ext)	Returns a file name that includes the given segment name, your own custom name and extension.
static String	stripExtension(String filename)	Removes the extension (anything after the first '.'), otherwise returns the original filename.
static String	stripSegmentName(String filename)	Strips the segment name out of the given file name.

Methods inherited from class java.lang.Object

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

Field Details

SEGMENTS

public static final String SEGMENTS

Name of the index segment file

See Also:

• Constant Field Values

PENDING_SEGMENTS

public static final String PENDING_SEGMENTS

Name of pending index segment file

See Also:

• Constant Field Values

CODEC_FILE_PATTERN

public static final Pattern CODEC_FILE_PATTERN

All files created by codecs much match this pattern (checked in SegmentInfo).

Method Details

fileNameFromGeneration

public static String fileNameFromGeneration(String base,
 String ext,
 long gen)

Computes the full file name from base, extension and generation. If the generation is -1, the file name is null. If it's 0, the file name is <base>.<ext>. If it's > 0, the file name is <base>_<gen>.<ext>.
NOTE: .<ext> is added to the name only if ext is not an empty string.

Parameters:

base - main part of the file name

ext - extension of the filename

gen - generation

segmentFileName

public static String segmentFileName(String segmentName,
 String segmentSuffix,
 String ext)

Returns a file name that includes the given segment name, your own custom name and extension. The format of the filename is: <segmentName>(_<name>)(.<ext>).

NOTE: .<ext> is added to the result file name only if ext is not empty.

NOTE: _<segmentSuffix> is added to the result file name only if it's not the empty string

NOTE: all custom files should be named using this method, or otherwise some structures may fail to handle them properly (such as if they are added to compound files).

matchesExtension

public static boolean matchesExtension(String filename,
 String ext)

Returns true if the given filename ends with the given extension. One should provide a pure extension, without '.'.

stripSegmentName

public static String stripSegmentName(String filename)

Strips the segment name out of the given file name. If you used segmentFileName(java.lang.String, java.lang.String, java.lang.String) or fileNameFromGeneration(java.lang.String, java.lang.String, long) to create your files, then this method simply removes whatever comes before the first '.', or the second '_' (excluding both).

Returns:

the filename with the segment name removed, or the given filename if it does not contain a '.' and '_'.

parseGeneration

public static long parseGeneration(String filename)

Returns the generation from this file name, or 0 if there is no generation.

parseSegmentName

public static String parseSegmentName(String filename)

Parses the segment name out of the given file name.

Returns:

the segment name only, or filename if it does not contain a '.' and '_'.

stripExtension

public static String stripExtension(String filename)

Removes the extension (anything after the first '.'), otherwise returns the original filename.

getExtension

public static String getExtension(String filename)

Return the extension (anything after the first '.'), or null if there is no '.' in the file name.