org.apache.lucene.search.highlight

Class QueryTermExtractor

java.lang.Object

org.apache.lucene.search.highlight.QueryTermExtractor

public final class QueryTermExtractor
extends Object

Utility class used to extract the terms used in a query, plus any weights. This class will not find terms for MultiTermQuery, TermRangeQuery and PrefixQuery classes so the caller must pass a rewritten query (see Query.rewrite) to obtain a list of expanded terms.

Constructor Summary

Constructors

Constructor and Description
QueryTermExtractor()

Method Summary

Modifier and Type	Method and Description
static WeightedTerm[]	getIdfWeightedTerms(Query query, IndexReader reader, String fieldName) Extracts all terms texts of a given Query into an array of WeightedTerms
static WeightedTerm[]	getTerms(Query query) Extracts all terms texts of a given Query into an array of WeightedTerms
static WeightedTerm[]	getTerms(Query query, boolean prohibited) Extracts all terms texts of a given Query into an array of WeightedTerms
static WeightedTerm[]	getTerms(Query query, boolean prohibited, String fieldName) Extracts all terms texts of a given Query into an array of WeightedTerms

Methods inherited from class java.lang.Object

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

Constructor Detail

QueryTermExtractor

public QueryTermExtractor()

Method Detail

getTerms

public static final WeightedTerm[] getTerms(Query query)

Extracts all terms texts of a given Query into an array of WeightedTerms

Parameters:

query - Query to extract term texts from

Returns:

an array of the terms used in a query, plus their weights.

getIdfWeightedTerms

public static final WeightedTerm[] getIdfWeightedTerms(Query query,
                                                       IndexReader reader,
                                                       String fieldName)

Extracts all terms texts of a given Query into an array of WeightedTerms

Parameters:

query - Query to extract term texts from

reader - used to compute IDF which can be used to a) score selected fragments better b) use graded highlights eg changing intensity of font color

fieldName - the field on which Inverse Document Frequency (IDF) calculations are based

Returns:

an array of the terms used in a query, plus their weights.

getTerms

public static WeightedTerm[] getTerms(Query query,
                                      boolean prohibited,
                                      String fieldName)

Extracts all terms texts of a given Query into an array of WeightedTerms

Parameters:

query - Query to extract term texts from

prohibited - true to extract "prohibited" terms, too

fieldName - The fieldName used to filter query terms

Returns:

an array of the terms used in a query, plus their weights.

getTerms

public static final WeightedTerm[] getTerms(Query query,
                                            boolean prohibited)

Extracts all terms texts of a given Query into an array of WeightedTerms

Parameters:

query - Query to extract term texts from

prohibited - true to extract "prohibited" terms, too

Returns:

an array of the terms used in a query, plus their weights.