Package org.apache.lucene.index

Class FilterDirectoryReader

java.lang.Object

org.apache.lucene.index.IndexReader

org.apache.lucene.index.CompositeReader

org.apache.lucene.index.BaseCompositeReader<AtomicReader>

org.apache.lucene.index.DirectoryReader

org.apache.lucene.index.FilterDirectoryReader

All Implemented Interfaces:

Closeable, AutoCloseable

public abstract class FilterDirectoryReader
extends DirectoryReader

A FilterDirectoryReader wraps another DirectoryReader, allowing implementations to transform or extend it. Subclasses should implement doWrapDirectoryReader to return an instance of the subclass. If the subclass wants to wrap the DirectoryReader's subreaders, it should also implement a SubReaderWrapper subclass, and pass an instance to its super constructor.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	FilterDirectoryReader.StandardReaderWrapper	A no-op SubReaderWrapper that simply returns the parent DirectoryReader's original subreaders.
static class	FilterDirectoryReader.SubReaderWrapper	Factory class passed to FilterDirectoryReader constructor that allows subclasses to wrap the filtered DirectoryReader's subreaders.

Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader

IndexReader.ReaderClosedListener

Field Summary

Fields inherited from class org.apache.lucene.index.DirectoryReader

DEFAULT_TERMS_INDEX_DIVISOR

Constructor Summary

Constructors

Constructor	Description
FilterDirectoryReader(DirectoryReader in)	Create a new FilterDirectoryReader that filters a passed in DirectoryReader.
FilterDirectoryReader(DirectoryReader in, FilterDirectoryReader.SubReaderWrapper wrapper)	Create a new FilterDirectoryReader that filters a passed in DirectoryReader, using the supplied SubReaderWrapper to wrap its subreader.

Method Summary

Modifier and Type	Method	Description
IndexCommit	getIndexCommit()	Expert: return the IndexCommit that this reader has opened.
long	getVersion()	Version number when this IndexReader was opened.
boolean	isCurrent()	Check whether any new changes have occurred to the index since this reader was opened.

Methods inherited from class org.apache.lucene.index.DirectoryReader

directory, indexExists, listCommits, open, open, open, open, open, openIfChanged, openIfChanged, openIfChanged

Methods inherited from class org.apache.lucene.index.BaseCompositeReader

docFreq, document, getDocCount, getSumDocFreq, getSumTotalTermFreq, getTermVectors, maxDoc, numDocs, totalTermFreq

Methods inherited from class org.apache.lucene.index.CompositeReader

getContext, toString

Methods inherited from class org.apache.lucene.index.IndexReader

addReaderClosedListener, close, decRef, document, document, equals, getCombinedCoreAndDeletesKey, getCoreCacheKey, getRefCount, getTermVector, hasDeletions, hashCode, incRef, leaves, numDeletedDocs, registerParentReader, removeReaderClosedListener, tryIncRef

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Details

FilterDirectoryReader

public FilterDirectoryReader(DirectoryReader in)

Create a new FilterDirectoryReader that filters a passed in DirectoryReader.

Parameters:

in - the DirectoryReader to filter

FilterDirectoryReader

public FilterDirectoryReader(DirectoryReader in,
 FilterDirectoryReader.SubReaderWrapper wrapper)

Create a new FilterDirectoryReader that filters a passed in DirectoryReader, using the supplied SubReaderWrapper to wrap its subreader.

Parameters:

in - the DirectoryReader to filter

wrapper - the SubReaderWrapper to use to wrap subreaders

Method Details

getVersion

public long getVersion()

Description copied from class: DirectoryReader

Version number when this IndexReader was opened.

This method returns the version recorded in the commit that the reader opened. This version is advanced every time a change is made with IndexWriter.

Specified by:

getVersion in class DirectoryReader

isCurrent

public boolean isCurrent()
                  throws IOException

Description copied from class: DirectoryReader

Check whether any new changes have occurred to the index since this reader was opened.

If this reader was created by calling DirectoryReader.open(org.apache.lucene.store.Directory), then this method checks if any further commits (see IndexWriter.commit()) have occurred in the directory.

If instead this reader is a near real-time reader (ie, obtained by a call to DirectoryReader.open(IndexWriter,boolean), or by calling DirectoryReader.openIfChanged(org.apache.lucene.index.DirectoryReader) on a near real-time reader), then this method checks if either a new commit has occurred, or any new uncommitted changes have taken place via the writer. Note that even if the writer has only performed merging, this method will still return false.

In any event, if this returns false, you should call DirectoryReader.openIfChanged(org.apache.lucene.index.DirectoryReader) to get a new reader that sees the changes.

Specified by:

isCurrent in class DirectoryReader

Throws:

IOException - if there is a low-level IO error

getIndexCommit

public IndexCommit getIndexCommit()
                           throws IOException

Description copied from class: DirectoryReader

Expert: return the IndexCommit that this reader has opened.

Specified by:

getIndexCommit in class DirectoryReader

Throws:

IOException