org.apache.lucene.index

Class 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.

    • 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 '.'.
      • 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.