Index Of Pdf Reader

[Earleen Statham]

I usually use this code... it's a class that encapsulates all the operations with the LuceneIndex (v4)
It uses near-real-time access to the index so nearly all updates are available to the index reader:

There are two different types of IndexReaders:

• LeafReader: These indexes do not consist of several sub-readers, they are atomic. They support retrieval of stored fields, doc values, terms, and postings.
• CompositeReader: Instances (like DirectoryReader) of this reader can only be used to get stored fields from the underlying LeafReaders, but it is not possible to directly retrieve postings. To do that, get the sub-readers via CompositeReader.getSequentialSubReaders().

IndexReader instances for indexes on disk are usually constructed with a call to one of the static DirectoryReader.open() methods, e.g. DirectoryReader.open(org.apache.lucene.store.Directory). DirectoryReader implements the CompositeReader interface, it is not possible to directly get postings. 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. NOTE: IndexReader instances are completely thread safe, meaning multiple threads can call any of its methods, concurrently. If your application requires external synchronization, you should not synchronize on the IndexReader instance; use your own (non-Lucene) objects instead.Nested Class SummaryNested Classes Modifier and TypeClass and Descriptionstatic interface IndexReader.CacheHelperA utility class that gives hooks in order to help build a cache based on the data that is contained in this index.static class IndexReader.CacheKeyA cache key identifying a resource that is being cached on.static interface IndexReader.ClosedListenerA listener that is called when a resource gets closed.Method SummaryAll Methods Instance Methods Abstract Methods Concrete Methods Modifier and TypeMethod and Descriptionvoidclose()Closes files associated with this index.voiddecRef()Expert: decreases the refCount of this IndexReader instance.abstract intdocFreq(Term term)Returns the number of documents containing the term.protected abstract voiddoClose()Implements close.Documentdocument(int docID)Returns the stored fields of the nth Document in this index.Documentdocument(int docID, Set fieldsToLoad)Like document(int) but only loads the specified fields.abstract voiddocument(int docID, StoredFieldVisitor visitor)Expert: visits the fields of a stored document, for custom processing/loading of each field.protected voidensureOpen()Throws AlreadyClosedException if this IndexReader or any of its child readers is closed, otherwise returns.booleanequals(Object obj)abstract IndexReaderContextgetContext()Expert: Returns the root IndexReaderContext for this IndexReader's sub-reader tree.abstract intgetDocCount(String field)Returns the number of documents that have at least one term for this field, or -1 if this measure isn't stored by the codec.abstract IndexReader.CacheHelpergetReaderCacheHelper()Optional method: Return a IndexReader.CacheHelper that can be used to cache based on the content of this reader.intgetRefCount()Expert: returns the current refCount for this readerabstract longgetSumDocFreq(String field)Returns the sum of TermsEnum.docFreq() for all terms in this field, or -1 if this measure isn't stored by the codec.abstract longgetSumTotalTermFreq(String field)Returns the sum of TermsEnum.totalTermFreq() for all terms in this field, or -1 if this measure isn't stored by the codec (or if this fields omits term freq and positions).TermsgetTermVector(int docID, String field)Retrieve term vector for this document and field, or null if term vectors were not indexed.abstract FieldsgetTermVectors(int docID)Retrieve term vectors for this document, or null if term vectors were not indexed.booleanhasDeletions()Returns true if any documents have been deleted.inthashCode()voidincRef()Expert: increments the refCount of this IndexReader instance.Listleaves()Returns the reader's leaves, or itself if this reader is atomic.abstract intmaxDoc()Returns one greater than the largest possible document number.intnumDeletedDocs()Returns the number of deleted documents.abstract intnumDocs()Returns the number of documents in this index.voidregisterParentReader(IndexReader reader)Expert: This method is called by IndexReaders which wrap other readers (e.g.abstract longtotalTermFreq(Term term)Returns the total number of occurrences of term across all documents (the sum of the freq() for each doc that has this term).booleantryIncRef()Expert: increments the refCount of this IndexReader instance only if the IndexReader has not been closed yet and returns true iff the refCount was successfully incremented, otherwise false.Methods inherited from class java.lang.Objectclone, finalize, getClass, notify, notifyAll, toString, wait, wait, waitMethod DetailregisterParentReaderpublic final void registerParentReader(IndexReader reader)Expert: This method is called by IndexReaders which wrap other readers (e.g. CompositeReader or FilterLeafReader) to register the parent at the child (this reader) on construction of the parent. When this reader is closed, it will mark all registered parents as closed, too. The references to parent readers are weak only, so they can be GCed once they are no longer in use.WARNING: This API is experimental and might change in incompatible ways in the next release.getRefCountpublic final int getRefCount()Expert: returns the current refCount for this readerincRefpublic final void incRef()Expert: increments the refCount of this IndexReader instance. RefCounts are used to determine when a reader can be closed safely, i.e. as soon as there are no more references. Be sure to always call a corresponding decRef(), in a finally clause; otherwise the reader may never be closed. Note that close() simply calls decRef(), which means that the IndexReader will not really be closed until decRef() has been called for all outstanding references.See Also:decRef(), tryIncRef()tryIncRefpublic final boolean tryIncRef()Expert: increments the refCount of this IndexReader instance only if the IndexReader has not been closed yet and returns true iff the refCount was successfully incremented, otherwise false. If this method returns false the reader is either already closed or is currently being closed. Either way this reader instance shouldn't be used by an application unless true is returned. RefCounts are used to determine when a reader can be closed safely, i.e. as soon as there are no more references. Be sure to always call a corresponding decRef(), in a finally clause; otherwise the reader may never be closed. Note that close() simply calls decRef(), which means that the IndexReader will not really be closed until decRef() has been called for all outstanding references.See Also:decRef(), incRef()decRefpublic final void decRef() throws IOExceptionExpert: decreases the refCount of this IndexReader instance. If the refCount drops to 0, then this reader is closed. If an exception is hit, the refCount is unchanged.Throws:IOException - in case an IOException occurs in doClose()See Also:incRef()ensureOpenprotected final void ensureOpen() throws AlreadyClosedExceptionThrows AlreadyClosedException if this IndexReader or any of its child readers is closed, otherwise returns.Throws:AlreadyClosedExceptionequalspublic final boolean equals(Object obj) IndexReader subclasses are not allowed to implement equals/hashCode, so methods are declared final.Overrides:equals in class ObjecthashCodepublic final int hashCode() IndexReader subclasses are not allowed to implement equals/hashCode, so methods are declared final.Overrides:hashCode in class ObjectgetTermVectorspublic abstract Fields getTermVectors(int docID) throws IOExceptionRetrieve term vectors for this document, or null if term vectors were not indexed. The returned Fields instance acts like a single-document inverted index (the docID will be 0).Throws:IOExceptiongetTermVectorpublic final Terms getTermVector(int docID, String field) throws IOExceptionRetrieve term vector for this document and field, or null if term vectors were not indexed. The returned Fields instance acts like a single-document inverted index (the docID will be 0).Throws:IOExceptionnumDocspublic abstract int numDocs()Returns the number of documents in this index.maxDocpublic abstract int maxDoc()Returns one greater than the largest possible document number. This may be used to, e.g., determine how big to allocate an array which will have an element for every document number in an index.numDeletedDocspublic final int numDeletedDocs()Returns the number of deleted documents.documentpublic abstract void document(int docID, StoredFieldVisitor visitor) throws IOExceptionExpert: visits the fields of a stored document, for custom processing/loading of each field. If you simply want to load all fields, use document(int). If you want to load a subset, use DocumentStoredFieldVisitor.Throws:IOExceptiondocumentpublic final Document document(int docID) throws IOExceptionReturns the stored fields of the nth Document in this index. This is just sugar for using DocumentStoredFieldVisitor. NOTE: for performance reasons, this method does not check if the requested document is deleted, and therefore asking for a deleted document may yield unspecified results. Usually this is not required, however you can test if the doc is deleted by checking the Bits returned from MultiFields.getLiveDocs(org.apache.lucene.index.IndexReader). NOTE: only the content of a field is returned, if that field was stored during indexing. Metadata like boost, omitNorm, IndexOptions, tokenized, etc., are not preserved.Throws:CorruptIndexException - if the index is corruptIOException - if there is a low-level IO errordocumentpublic final Document document(int docID, Set fieldsToLoad) throws IOExceptionLike document(int) but only loads the specified fields. Note that this is simply sugar for DocumentStoredFieldVisitor.DocumentStoredFieldVisitor(Set).Throws:IOExceptionhasDeletionspublic boolean hasDeletions()Returns true if any documents have been deleted. Implementers should consider overriding this method if maxDoc() or numDocs() are not constant-time operations.closepublic final void close() throws IOExceptionCloses files associated with this index. Also saves any new deletions to disk. No other methods should be called after this has been called.Specified by:close in interface CloseableSpecified by:close in interface AutoCloseableThrows:IOException - if there is a low-level IO errordoCloseprotected abstract void doClose() throws IOExceptionImplements close.Throws:IOExceptiongetContextpublic abstract IndexReaderContext getContext()Expert: Returns the root IndexReaderContext for this IndexReader's sub-reader tree. Iff this reader is composed of sub readers, i.e. this reader being a composite reader, this method returns a CompositeReaderContext holding the reader's direct children as well as a view of the reader tree's atomic leaf contexts. All sub- IndexReaderContext instances referenced from this readers top-level context are private to this reader and are not shared with another context tree. For example, IndexSearcher uses this API to drive searching by one atomic leaf reader at a time. If this reader is not composed of child readers, this method returns an LeafReaderContext. Note: Any of the sub-CompositeReaderContext instances referenced from this top-level context do not support CompositeReaderContext.leaves(). Only the top-level context maintains the convenience leaf-view for performance reasons.leavespublic final List leaves()Returns the reader's leaves, or itself if this reader is atomic. This is a convenience method calling this.getContext().leaves().See Also:IndexReaderContext.leaves()getReaderCacheHelperpublic abstract IndexReader.CacheHelper getReaderCacheHelper()Optional method: Return a IndexReader.CacheHelper that can be used to cache based on the content of this reader. Two readers that have different data or different sets of deleted documents will be considered different. A return value of null indicates that this reader is not suited for caching, which is typically the case for short-lived wrappers that alter the content of the wrapped reader.WARNING: This API is experimental and might change in incompatible ways in the next release.docFreqpublic abstract int docFreq(Term term) throws IOExceptionReturns the number of documents containing the term. This method returns 0 if the term or field does not exists. This method does not take into account deleted documents that have not yet been merged away.Throws:IOExceptionSee Also:TermsEnum.docFreq()totalTermFreqpublic abstract long totalTermFreq(Term term) throws IOExceptionReturns the total number of occurrences of term across all documents (the sum of the freq() for each doc that has this term). This will be -1 if the codec doesn't support this measure. Note that, like other term measures, this measure does not take deleted documents into account.Throws:IOExceptiongetSumDocFreqpublic abstract long getSumDocFreq(String field) throws IOExceptionReturns the sum of TermsEnum.docFreq() for all terms in this field, or -1 if this measure isn't stored by the codec. Note that, just like other term measures, this measure does not take deleted documents into account.Throws:IOExceptionSee Also:Terms.getSumDocFreq()getDocCountpublic abstract int getDocCount(String field) throws IOExceptionReturns the number of documents that have at least one term for this field, or -1 if this measure isn't stored by the codec. Note that, just like other term measures, this measure does not take deleted documents into account.Throws:IOExceptionSee Also:Terms.getDocCount()getSumTotalTermFreqpublic abstract long getSumTotalTermFreq(String field) throws IOExceptionReturns the sum of TermsEnum.totalTermFreq() for all terms in this field, or -1 if this measure isn't stored by the codec (or if this fields omits term freq and positions). Note that, just like other term measures, this measure does not take deleted documents into account.Throws:IOExceptionSee Also:Terms.getSumTotalTermFreq()Skip navigation links

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