|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
java.lang.Objectorg.apache.lucene.index.IndexReader
public abstract class IndexReader
IndexReader is an abstract class, providing an interface for accessing an index. Search of an index is done entirely through this abstract interface, so that any subclass which implements it is searchable.
Concrete subclasses of IndexReader are usually constructed with a call to
one of the static open()
methods, e.g. open(String)
.
For efficiency, in this API documents are often referred to via document numbers, non-negative integers which each name a unique document in the index. These document numbers are ephemeral--they may change as documents are added to and deleted from an index. Clients should thus not rely on a given document having the same number between sessions.
An IndexReader can be opened on a directory for which an IndexWriter is opened already, but it cannot be used to delete documents from the index then.
Nested Class Summary | |
---|---|
static class |
IndexReader.FieldOption
|
Constructor Summary | |
---|---|
protected |
IndexReader(Directory directory)
Constructor used if IndexReader is not owner of its directory. |
Method Summary | |
---|---|
void |
close()
Closes files associated with this index. |
protected void |
commit()
Commit changes resulting from delete, undeleteAll, or setNorm operations |
void |
delete(int docNum)
Deprecated. Use deleteDocument(int docNum) instead. |
int |
delete(Term term)
Deprecated. Use deleteDocuments(Term term) instead. |
void |
deleteDocument(int docNum)
Deletes the document numbered docNum . |
int |
deleteDocuments(Term term)
Deletes all documents containing term . |
Directory |
directory()
Returns the directory this index resides in. |
abstract int |
docFreq(Term t)
Returns the number of documents containing the term t . |
protected abstract void |
doClose()
Implements close. |
protected abstract void |
doCommit()
Implements commit. |
abstract Document |
document(int n)
Returns the stored fields of the n th
Document in this index. |
protected abstract void |
doDelete(int docNum)
Implements deletion of the document numbered docNum . |
protected abstract void |
doSetNorm(int doc,
String field,
byte value)
Implements setNorm in subclass. |
protected abstract void |
doUndeleteAll()
Implements actual undeleteAll() in subclass. |
protected void |
finalize()
Release the write lock, if needed. |
static long |
getCurrentVersion(Directory directory)
Reads version number from segments files. |
static long |
getCurrentVersion(File directory)
Reads version number from segments files. |
static long |
getCurrentVersion(String directory)
Reads version number from segments files. |
abstract Collection |
getFieldNames()
Deprecated. Replaced by getFieldNames(IndexReader.FieldOption) |
abstract Collection |
getFieldNames(boolean indexed)
Deprecated. Replaced by getFieldNames(IndexReader.FieldOption) |
abstract Collection |
getFieldNames(IndexReader.FieldOption fldOption)
Get a list of unique field names that exist in this index and have the specified field option information. |
Collection |
getIndexedFieldNames(boolean storedTermVector)
Deprecated. Replaced by getFieldNames(IndexReader.FieldOption) |
abstract Collection |
getIndexedFieldNames(Field.TermVector tvSpec)
Deprecated. Replaced by getFieldNames(IndexReader.FieldOption) |
abstract TermFreqVector |
getTermFreqVector(int docNumber,
String field)
Return a term frequency vector for the specified document and field. |
abstract TermFreqVector[] |
getTermFreqVectors(int docNumber)
Return an array of term frequency vectors for the specified document. |
long |
getVersion()
Version number when this IndexReader was opened. |
abstract boolean |
hasDeletions()
Returns true if any documents have been deleted |
boolean |
hasNorms(String field)
Returns true if there are norms stored for this field. |
static boolean |
indexExists(Directory directory)
Returns true if an index exists at the specified directory. |
static boolean |
indexExists(File directory)
Returns true if an index exists at the specified directory. |
static boolean |
indexExists(String directory)
Returns true if an index exists at the specified directory. |
boolean |
isCurrent()
Check whether this IndexReader still works on a current version of the index. |
abstract boolean |
isDeleted(int n)
Returns true if document n has been deleted |
static boolean |
isLocked(Directory directory)
Returns true iff the index in the named directory is
currently locked. |
static boolean |
isLocked(String directory)
Returns true iff the index in the named directory is
currently locked. |
static long |
lastModified(Directory directory)
Returns the time the index in the named directory was last modified. |
static long |
lastModified(File directory)
Returns the time the index in the named directory was last modified. |
static long |
lastModified(String directory)
Returns the time the index in the named directory was last modified. |
static void |
main(String[] args)
Prints the filename and size of each file within a given compound file. |
abstract int |
maxDoc()
Returns one greater than the largest possible document number. |
abstract byte[] |
norms(String field)
Returns the byte-encoded normalization factor for the named field of every document. |
abstract void |
norms(String field,
byte[] bytes,
int offset)
Reads the byte-encoded normalization factor for the named field of every document. |
abstract int |
numDocs()
Returns the number of documents in this index. |
static IndexReader |
open(Directory directory)
Returns an IndexReader reading the index in the given Directory. |
static IndexReader |
open(File path)
Returns an IndexReader reading the index in an FSDirectory in the named path. |
static IndexReader |
open(String path)
Returns an IndexReader reading the index in an FSDirectory in the named path. |
void |
setNorm(int doc,
String field,
byte value)
Expert: Resets the normalization factor for the named field of the named document. |
void |
setNorm(int doc,
String field,
float value)
Expert: Resets the normalization factor for the named field of the named document. |
abstract TermDocs |
termDocs()
Returns an unpositioned TermDocs enumerator. |
TermDocs |
termDocs(Term term)
Returns an enumeration of all the documents which contain term . |
abstract TermPositions |
termPositions()
Returns an unpositioned TermPositions enumerator. |
TermPositions |
termPositions(Term term)
Returns an enumeration of all the documents which contain term . |
abstract TermEnum |
terms()
Returns an enumeration of all the terms in the index. |
abstract TermEnum |
terms(Term t)
Returns an enumeration of all terms after a given term. |
void |
undeleteAll()
Undeletes all documents currently marked as deleted in this index. |
static void |
unlock(Directory directory)
Forcibly unlocks the index in the named directory. |
Methods inherited from class java.lang.Object |
---|
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
---|
protected IndexReader(Directory directory)
directory
- Directory where IndexReader files reside.Method Detail |
---|
public static IndexReader open(String path) throws IOException
IOException
public static IndexReader open(File path) throws IOException
IOException
public static IndexReader open(Directory directory) throws IOException
IOException
public Directory directory()
public static long lastModified(String directory) throws IOException
isCurrent()
instead.
IOException
public static long lastModified(File directory) throws IOException
isCurrent()
instead.
IOException
public static long lastModified(Directory directory) throws IOException
isCurrent()
instead.
IOException
public static long getCurrentVersion(String directory) throws IOException
directory
- where the index resides.
IOException
- if segments file cannot be readpublic static long getCurrentVersion(File directory) throws IOException
directory
- where the index resides.
IOException
- if segments file cannot be readpublic static long getCurrentVersion(Directory directory) throws IOException
directory
- where the index resides.
IOException
- if segments file cannot be read.public long getVersion()
public boolean isCurrent() throws IOException
IOException
public abstract TermFreqVector[] getTermFreqVectors(int docNumber) throws IOException
docNumber
- document for which term frequency vectors are returned
IOException
- if index cannot be accessedField.TermVector
public abstract TermFreqVector getTermFreqVector(int docNumber, String field) throws IOException
docNumber
- document for which the term frequency vector is returnedfield
- field for which the term frequency vector is returned.
IOException
- if index cannot be accessedField.TermVector
public static boolean indexExists(String directory)
true
if an index exists at the specified directory.
If the directory does not exist or if there is no index in it.
false
is returned.
directory
- the directory to check for an index
true
if an index exists; false
otherwisepublic static boolean indexExists(File directory)
true
if an index exists at the specified directory.
If the directory does not exist or if there is no index in it.
directory
- the directory to check for an index
true
if an index exists; false
otherwisepublic static boolean indexExists(Directory directory) throws IOException
true
if an index exists at the specified directory.
If the directory does not exist or if there is no index in it.
directory
- the directory to check for an index
true
if an index exists; false
otherwise
IOException
- if there is a problem with accessing the indexpublic abstract int numDocs()
public abstract int maxDoc()
public abstract Document document(int n) throws IOException
n
th
Document
in this index.
IOException
public abstract boolean isDeleted(int n)
public abstract boolean hasDeletions()
public boolean hasNorms(String field) throws IOException
IOException
public abstract byte[] norms(String field) throws IOException
IOException
Field.setBoost(float)
public abstract void norms(String field, byte[] bytes, int offset) throws IOException
IOException
Field.setBoost(float)
public final void setNorm(int doc, String field, byte value) throws IOException
boost
and its length normalization
. Thus, to preserve the length normalization
values when resetting this, one should base the new value upon the old.
IOException
norms(String)
,
Similarity.decodeNorm(byte)
protected abstract void doSetNorm(int doc, String field, byte value) throws IOException
IOException
public void setNorm(int doc, String field, float value) throws IOException
IOException
norms(String)
,
Similarity.decodeNorm(byte)
public abstract TermEnum terms() throws IOException
IOException
public abstract TermEnum terms(Term t) throws IOException
IOException
public abstract int docFreq(Term t) throws IOException
t
.
IOException
public TermDocs termDocs(Term term) throws IOException
term
. For each document, the document number, the frequency of
the term in that document is also provided, for use in search scoring.
Thus, this method implements the mapping:
The enumeration is ordered by document number. Each document number is greater than all that precede it in the enumeration.
IOException
public abstract TermDocs termDocs() throws IOException
TermDocs
enumerator.
IOException
public TermPositions termPositions(Term term) throws IOException
term
. For each document, in addition to the document number
and frequency of the term in that document, a list of all of the ordinal
positions of the term in the document is available. Thus, this method
implements the mapping:
This positional information faciliates phrase and proximity searching.
The enumeration is ordered by document number. Each document number is greater than all that precede it in the enumeration.
IOException
public abstract TermPositions termPositions() throws IOException
TermPositions
enumerator.
IOException
public final void delete(int docNum) throws IOException
deleteDocument(int docNum)
instead.
docNum
. Once a document is
deleted it will not appear in TermDocs or TermPostitions enumerations.
Attempts to read its field with the document(int)
method will result in an error. The presence of this document may still be
reflected in the docFreq(org.apache.lucene.index.Term)
statistic, though
this will be corrected eventually as the index is further modified.
IOException
public final void deleteDocument(int docNum) throws IOException
docNum
. Once a document is
deleted it will not appear in TermDocs or TermPostitions enumerations.
Attempts to read its field with the document(int)
method will result in an error. The presence of this document may still be
reflected in the docFreq(org.apache.lucene.index.Term)
statistic, though
this will be corrected eventually as the index is further modified.
IOException
protected abstract void doDelete(int docNum) throws IOException
docNum
.
Applications should call delete(int)
or delete(Term)
.
IOException
public final int delete(Term term) throws IOException
deleteDocuments(Term term)
instead.
term
.
This is useful if one uses a document field to hold a unique ID string for
the document. Then to delete such a document, one merely constructs a
term with the appropriate field and the unique ID string as its text and
passes it to this method.
See delete(int)
for information about when this deletion will
become effective.
IOException
public final int deleteDocuments(Term term) throws IOException
term
.
This is useful if one uses a document field to hold a unique ID string for
the document. Then to delete such a document, one merely constructs a
term with the appropriate field and the unique ID string as its text and
passes it to this method.
See delete(int)
for information about when this deletion will
become effective.
IOException
public final void undeleteAll() throws IOException
IOException
protected abstract void doUndeleteAll() throws IOException
IOException
protected final void commit() throws IOException
IOException
protected abstract void doCommit() throws IOException
IOException
public final void close() throws IOException
IOException
protected abstract void doClose() throws IOException
IOException
protected void finalize()
finalize
in class Object
public abstract Collection getFieldNames() throws IOException
getFieldNames(IndexReader.FieldOption)
IOException
- if there is a problem with accessing the indexpublic abstract Collection getFieldNames(boolean indexed) throws IOException
getFieldNames(IndexReader.FieldOption)
indexed
- true
if only indexed fields should be returned;
false
if only unindexed fields should be returned.
IOException
- if there is a problem with accessing the indexpublic Collection getIndexedFieldNames(boolean storedTermVector)
getFieldNames(IndexReader.FieldOption)
storedTermVector
- if true, returns only Indexed fields that have term vector info,
else only indexed fields without term vector info
public abstract Collection getIndexedFieldNames(Field.TermVector tvSpec)
getFieldNames(IndexReader.FieldOption)
tvSpec
- specifies which term vector information should be available for the fields
public abstract Collection getFieldNames(IndexReader.FieldOption fldOption)
fldOption
- specifies which field option should be available for the returned fields
IndexReader.FieldOption
public static boolean isLocked(Directory directory) throws IOException
true
iff the index in the named directory is
currently locked.
directory
- the directory to check for a lock
IOException
- if there is a problem with accessing the indexpublic static boolean isLocked(String directory) throws IOException
true
iff the index in the named directory is
currently locked.
directory
- the directory to check for a lock
IOException
- if there is a problem with accessing the indexpublic static void unlock(Directory directory) throws IOException
Caution: this should only be used by failure recovery code, when it is known that no other process nor thread is in fact currently accessing this index.
IOException
public static void main(String[] args)
args
- Usage: org.apache.lucene.index.IndexReader [-extract] <cfsfile>
|
||||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |