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

static String	COMPOUND_FILE_ENTRIES_EXTENSION Extension of compound file entries
static String	COMPOUND_FILE_EXTENSION Extension of compound file
static String	GEN_EXTENSION Extension of gen file
static String[]	INDEX_EXTENSIONS This array contains all filename extensions used by Lucene's index files, with one exception, namely the extension made up from .s + a number.
static String	SEGMENTS Name of the index segment file
static String	SEGMENTS_GEN Name of the generation reference file name

Method Summary

static String	fileNameFromGeneration(String base, String ext, long gen) Computes the full file name from base, extension and generation.
static boolean	matchesExtension(String filename, String ext) Returns true if the given filename ends with the given extension.
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 Detail

SEGMENTS

public static final String SEGMENTS

Name of the index segment file

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Constant Field Values

GEN_EXTENSION

public static final String GEN_EXTENSION

Extension of gen file

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Constant Field Values

SEGMENTS_GEN

public static final String SEGMENTS_GEN

Name of the generation reference file name

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Constant Field Values

COMPOUND_FILE_EXTENSION

public static final String COMPOUND_FILE_EXTENSION

Extension of compound file

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Constant Field Values

COMPOUND_FILE_ENTRIES_EXTENSION

public static final String COMPOUND_FILE_ENTRIES_EXTENSION

Extension of compound file entries

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Constant Field Values

INDEX_EXTENSIONS

public static final String[] INDEX_EXTENSIONS

This array contains all filename extensions used by Lucene's index files, with one exception, namely the extension made up from .s + a number. Also note that Lucene's segments_N files do not have any filename extension.

Method Detail

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 '_'.

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.