org.apache.lucene.search.postingshighlight

Class CustomPostingsHighlighter

java.lang.Object

org.apache.lucene.search.postingshighlight.PostingsHighlighter

org.apache.lucene.search.postingshighlight.CustomPostingsHighlighter

public final class CustomPostingsHighlighter
extends org.apache.lucene.search.postingshighlight.PostingsHighlighter

Subclass of the PostingsHighlighter that works for a single field in a single document. Uses a custom PassageFormatter. Accepts field content as a constructor argument, given that loading is custom and can be done reading from _source field. Supports using different BreakIterator to break the text into fragments. Considers every distinct field value as a discrete passage for highlighting (unless the whole content needs to be highlighted). Supports both returning empty snippets and non highlighted snippets when no highlighting can be performed. The use that we make of the postings highlighter is not optimal. It would be much better to highlight multiple docs in a single call, as we actually lose its sequential IO. That would require to refactor the elasticsearch highlight api which currently works per hit.

Field Summary

Fields inherited from class org.apache.lucene.search.postingshighlight.PostingsHighlighter

DEFAULT_MAX_LENGTH

Constructor Summary

Constructors

Constructor and Description
CustomPostingsHighlighter(org.apache.lucene.analysis.Analyzer analyzer, CustomPassageFormatter passageFormatter, BreakIterator breakIterator, String fieldValue, boolean returnNonHighlightedSnippets) Creates a new instance of CustomPostingsHighlighter
CustomPostingsHighlighter(org.apache.lucene.analysis.Analyzer analyzer, CustomPassageFormatter passageFormatter, String fieldValue, boolean returnNonHighlightedSnippets) Creates a new instance of CustomPostingsHighlighter

Method Summary

Methods

Modifier and Type	Method and Description
protected BreakIterator	getBreakIterator(String field)
protected org.apache.lucene.search.postingshighlight.Passage[]	getEmptyHighlight(String fieldName, BreakIterator bi, int maxPassages)
protected org.apache.lucene.search.postingshighlight.PassageFormatter	getFormatter(String field)
protected org.apache.lucene.analysis.Analyzer	getIndexAnalyzer(String field)
Snippet[]	highlightField(String field, org.apache.lucene.search.Query query, org.apache.lucene.search.IndexSearcher searcher, int docId, int maxPassages) Highlights terms extracted from the provided query within the content of the provided field name
protected String[][]	loadFieldValues(org.apache.lucene.search.IndexSearcher searcher, String[] fields, int[] docids, int maxLength)

Methods inherited from class org.apache.lucene.search.postingshighlight.PostingsHighlighter

getMultiValuedSeparator, getScorer, highlight, highlight, highlightFields, highlightFields, highlightFields, highlightFieldsAsObjects

Methods inherited from class java.lang.Object

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

Constructor Detail

CustomPostingsHighlighter

public CustomPostingsHighlighter(org.apache.lucene.analysis.Analyzer analyzer,
                         CustomPassageFormatter passageFormatter,
                         String fieldValue,
                         boolean returnNonHighlightedSnippets)

Creates a new instance of CustomPostingsHighlighter

Parameters:

analyzer - the analyzer used for the field at index time, used for multi term queries internally

passageFormatter - our own PassageFormatter which generates snippets in forms of Snippet objects

fieldValue - the original field values as constructor argument, loaded from te _source field or the relevant stored field.

returnNonHighlightedSnippets - whether non highlighted snippets should be returned rather than empty snippets when no highlighting can be performed

CustomPostingsHighlighter

public CustomPostingsHighlighter(org.apache.lucene.analysis.Analyzer analyzer,
                         CustomPassageFormatter passageFormatter,
                         BreakIterator breakIterator,
                         String fieldValue,
                         boolean returnNonHighlightedSnippets)

Creates a new instance of CustomPostingsHighlighter

Parameters:

analyzer - the analyzer used for the field at index time, used for multi term queries internally

passageFormatter - our own PassageFormatter which generates snippets in forms of Snippet objects

breakIterator - an instance BreakIterator selected depending on the highlighting options

fieldValue - the original field values as constructor argument, loaded from te _source field or the relevant stored field.

returnNonHighlightedSnippets - whether non highlighted snippets should be returned rather than empty snippets when no highlighting can be performed

Method Detail

highlightField

public Snippet[] highlightField(String field,
                       org.apache.lucene.search.Query query,
                       org.apache.lucene.search.IndexSearcher searcher,
                       int docId,
                       int maxPassages)
                         throws IOException

Highlights terms extracted from the provided query within the content of the provided field name

Throws:

IOException

getFormatter

protected org.apache.lucene.search.postingshighlight.PassageFormatter getFormatter(String field)

Overrides:

getFormatter in class org.apache.lucene.search.postingshighlight.PostingsHighlighter

getBreakIterator

protected BreakIterator getBreakIterator(String field)

Overrides:

getBreakIterator in class org.apache.lucene.search.postingshighlight.PostingsHighlighter

getEmptyHighlight

protected org.apache.lucene.search.postingshighlight.Passage[] getEmptyHighlight(String fieldName,
                                                                     BreakIterator bi,
                                                                     int maxPassages)

Overrides:

getEmptyHighlight in class org.apache.lucene.search.postingshighlight.PostingsHighlighter

getIndexAnalyzer

protected org.apache.lucene.analysis.Analyzer getIndexAnalyzer(String field)

Overrides:

getIndexAnalyzer in class org.apache.lucene.search.postingshighlight.PostingsHighlighter

loadFieldValues

protected String[][] loadFieldValues(org.apache.lucene.search.IndexSearcher searcher,
                         String[] fields,
                         int[] docids,
                         int maxLength)
                              throws IOException

Overrides:

loadFieldValues in class org.apache.lucene.search.postingshighlight.PostingsHighlighter

Throws:

IOException