Package org.apache.lucene.search.highlight

Class Highlighter

java.lang.Object
org.apache.lucene.search.highlight.Highlighter
public class Highlighter extends Object
Marks up highlighted terms found in the best sections of text, using configurable Fragmenter, Scorer, Formatter, Encoder and tokenizers.

This is Lucene's original Highlighter; there are others.

  • Field Details

    • DEFAULT_MAX_CHARS_TO_ANALYZE

      public static final int DEFAULT_MAX_CHARS_TO_ANALYZE
      See Also:

  • Constructor Details

    • Highlighter

      public Highlighter(Scorer fragmentScorer)

    • Highlighter

      public Highlighter(Formatter formatter, Scorer fragmentScorer)

    • Highlighter

      public Highlighter(Formatter formatter, Encoder encoder, Scorer fragmentScorer)

  • Method Details

    • getBestFragment

      public final String getBestFragment(Analyzer analyzer, String fieldName, String text) throws IOException, InvalidTokenOffsetsException
      Highlights chosen terms in a text, extracting the most relevant section. This is a convenience method that calls getBestFragment(TokenStream, String)
      Parameters:
      analyzer - the analyzer that will be used to split text into chunks
      text - text to highlight terms in
      fieldName - Name of field used to influence analyzer's tokenization policy
      Returns:
      highlighted text fragment or null if no terms found
      Throws:
      InvalidTokenOffsetsException - thrown if any token's endOffset exceeds the provided text's length
      IOException

    • getBestFragment

      public final String getBestFragment(TokenStream tokenStream, String text) throws IOException, InvalidTokenOffsetsException
      Highlights chosen terms in a text, extracting the most relevant section. The document text is analysed in chunks to record hit statistics across the document. After accumulating stats, the fragment with the highest score is returned
      Parameters:
      tokenStream - a stream of tokens identified in the text parameter, including offset information. This is typically produced by an analyzer re-parsing a document's text. Some work may be done on retrieving TokenStreams more efficiently by adding support for storing original text position data in the Lucene index but this support is not currently available (as of Lucene 1.4 rc2).
      text - text to highlight terms in
      Returns:
      highlighted text fragment or null if no terms found
      Throws:
      InvalidTokenOffsetsException - thrown if any token's endOffset exceeds the provided text's length
      IOException

    • getBestFragments

      public final String[] getBestFragments(Analyzer analyzer, String fieldName, String text, int maxNumFragments) throws IOException, InvalidTokenOffsetsException
      Highlights chosen terms in a text, extracting the most relevant sections. This is a convenience method that calls getBestFragments(TokenStream, String, int)
      Parameters:
      analyzer - the analyzer that will be used to split text into chunks
      fieldName - the name of the field being highlighted (used by analyzer)
      text - text to highlight terms in
      maxNumFragments - the maximum number of fragments.
      Returns:
      highlighted text fragments (between 0 and maxNumFragments number of fragments)
      Throws:
      InvalidTokenOffsetsException - thrown if any token's endOffset exceeds the provided text's length
      IOException

    • getBestFragments

      public final String[] getBestFragments(TokenStream tokenStream, String text, int maxNumFragments) throws IOException, InvalidTokenOffsetsException
      Highlights chosen terms in a text, extracting the most relevant sections. The document text is analysed in chunks to record hit statistics across the document. After accumulating stats, the fragments with the highest scores are returned as an array of strings in order of score (contiguous fragments are merged into one in their original order to improve readability)
      Parameters:
      text - text to highlight terms in
      maxNumFragments - the maximum number of fragments.
      Returns:
      highlighted text fragments (between 0 and maxNumFragments number of fragments)
      Throws:
      InvalidTokenOffsetsException - thrown if any token's endOffset exceeds the provided text's length
      IOException

    • getBestTextFragments

      public final TextFragment[] getBestTextFragments(TokenStream tokenStream, String text, boolean mergeContiguousFragments, int maxNumFragments) throws IOException, InvalidTokenOffsetsException
      Low level api to get the most relevant (formatted) sections of the document. This method has been made public to allow visibility of score information held in TextFragment objects. Thanks to Jason Calabrese for help in redefining the interface.
      Throws:
      IOException - If there is a low-level I/O error
      InvalidTokenOffsetsException - thrown if any token's endOffset exceeds the provided text's length

    • getBestFragments

      public final String getBestFragments(TokenStream tokenStream, String text, int maxNumFragments, String separator) throws IOException, InvalidTokenOffsetsException
      Highlights terms in the text , extracting the most relevant sections and concatenating the chosen fragments with a separator (typically "..."). The document text is analysed in chunks to record hit statistics across the document. After accumulating stats, the fragments with the highest scores are returned in order as "separator" delimited strings.
      Parameters:
      text - text to highlight terms in
      maxNumFragments - the maximum number of fragments.
      separator - the separator used to intersperse the document fragments (typically "...")
      Returns:
      highlighted text
      Throws:
      InvalidTokenOffsetsException - thrown if any token's endOffset exceeds the provided text's length
      IOException

    • getMaxDocCharsToAnalyze

      public int getMaxDocCharsToAnalyze()

    • setMaxDocCharsToAnalyze

      public void setMaxDocCharsToAnalyze(int maxDocCharsToAnalyze)

    • getTextFragmenter

      public Fragmenter getTextFragmenter()

    • setTextFragmenter

      public void setTextFragmenter(Fragmenter fragmenter)

    • getFragmentScorer

      public Scorer getFragmentScorer()
      Returns:
      Object used to score each text fragment

    • setFragmentScorer

      public void setFragmentScorer(Scorer scorer)

    • getEncoder

      public Encoder getEncoder()

    • setEncoder

      public void setEncoder(Encoder encoder)