org.apache.lucene.search

Class IndexSearcher

Implemented Interfaces:
Remote, Searchable

public class IndexSearcher
extends Searcher

Implements search over a single IndexReader.

Applications usually need only call the inherited search(Query) or search(Query,Filter) methods. For performance reasons it is recommended to open only one IndexSearcher and use it for all of your searches.

Note that you can only access Hits from an IndexSearcher as long as it is not yet closed, otherwise an IOException will be thrown.

Constructor Summary

IndexSearcher(String path)
Creates a searcher searching the index in the named directory.
IndexSearcher(IndexReader r)
Creates a searcher searching the provided index.
IndexSearcher(Directory directory)
Creates a searcher searching the index in the provided directory.

Method Summary

void
close()
Note that the underlying IndexReader is not closed, if IndexSearcher was constructed with IndexSearcher(IndexReader r).
Document
doc(int i)
Expert: Returns the stored fields of document i.
int
docFreq(Term term)
Expert: Returns the number of documents containing term.
Explanation
explain(Weight weight, int doc)
Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.
IndexReader
getIndexReader()
Return the IndexReader this searches.
int
maxDoc()
Expert: Returns one greater than the largest possible document number.
Query
rewrite(Query original)
Expert: called to re-write queries into primitive queries.
TopDocs
search(Weight weight, Filter filter, int nDocs)
Expert: Low-level search implementation.
TopFieldDocs
search(Weight weight, Filter filter, int nDocs, Sort sort)
Expert: Low-level search implementation with arbitrary sorting.
void
search(Weight weight, Filter filter, HitCollector results)
Lower-level search API.

Methods inherited from class org.apache.lucene.search.Searcher

close, createWeight, doc, docFreq, docFreqs, explain, explain, getSimilarity, maxDoc, rewrite, search, search, search, search, search, search, search, search, search, search, search, setSimilarity

Constructor Details

IndexSearcher

public IndexSearcher(String path)
            throws IOException
Creates a searcher searching the index in the named directory.

IndexSearcher

public IndexSearcher(IndexReader r)
Creates a searcher searching the provided index.

IndexSearcher

public IndexSearcher(Directory directory)
            throws IOException
Creates a searcher searching the index in the provided directory.

Method Details

close

public void close()
            throws IOException
Note that the underlying IndexReader is not closed, if IndexSearcher was constructed with IndexSearcher(IndexReader r). If the IndexReader was supplied implicitly by specifying a directory, then the IndexReader gets closed.
Specified by:
close in interface Searchable
Overrides:
close in interface Searcher

doc

public Document doc(int i)
            throws IOException
Expert: Returns the stored fields of document i. Called by HitCollector implementations.
Specified by:
doc in interface Searchable
Overrides:
doc in interface Searcher

docFreq

public int docFreq(Term term)
            throws IOException
Expert: Returns the number of documents containing term. Called by search code to compute term weights.
Specified by:
docFreq in interface Searchable
Overrides:
docFreq in interface Searcher

explain

public Explanation explain(Weight weight,
                           int doc)
            throws IOException
Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.

This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.

Applications should call Searcher.explain(Query,int).

Specified by:
explain in interface Searchable
Overrides:
explain in interface Searcher

getIndexReader

public IndexReader getIndexReader()
Return the IndexReader this searches.

maxDoc

public int maxDoc()
            throws IOException
Expert: Returns one greater than the largest possible document number. Called by search code to compute term weights.
Specified by:
maxDoc in interface Searchable
Overrides:
maxDoc in interface Searcher

rewrite

public Query rewrite(Query original)
            throws IOException
Expert: called to re-write queries into primitive queries.
Specified by:
rewrite in interface Searchable
Overrides:
rewrite in interface Searcher

search

public TopDocs search(Weight weight,
                      Filter filter,
                      int nDocs)
            throws IOException
Expert: Low-level search implementation. Finds the top n hits for query, applying filter if non-null.

Called by Hits.

Applications should usually call Searcher.search(Query) or Searcher.search(Query,Filter) instead.

Specified by:
search in interface Searchable
Overrides:
search in interface Searcher

search

public TopFieldDocs search(Weight weight,
                           Filter filter,
                           int nDocs,
                           Sort sort)
            throws IOException
Expert: Low-level search implementation with arbitrary sorting. Finds the top n hits for query, applying filter if non-null, and sorting the hits by the criteria in sort.

Applications should usually call Searcher.search(Query,Filter,Sort) instead.

Specified by:
search in interface Searchable
Overrides:
search in interface Searcher

search

public void search(Weight weight,
                   Filter filter,
                   HitCollector results)
            throws IOException
Lower-level search API.

HitCollector.collect(int,float) is called for every non-zero scoring document.
HitCollector-based access to remote indexes is discouraged.

Applications should only use this if they need all of the matching documents. The high-level search API (Searcher.search(Query)) is usually more efficient, as it skips non-high-scoring hits.

Specified by:
search in interface Searchable
Overrides:
search in interface Searcher
Parameters:
weight - to match documents
filter - if non-null, a bitset used to eliminate some documents
results - to receive hits

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