Concrete subclasses of IndexReader are usually constructed with a call to
- one of the static open() methods, e.g. {@link
- #open(Directory)}.
-
-
For efficiency, in this API documents are often referred to via +
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 + 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: for backwards API compatibility, several methods are not listed - as abstract, but have no useful implementations in this base class and - instead always throw UnsupportedOperationException. Subclasses are - strongly encouraged to override these methods, but in many cases may not - need to. -
- -NOTE: {@link IndexReader} instances are completely thread safe, meaning multiple threads can call any of its methods, diff --git a/lucene/src/java/org/apache/lucene/index/CompositeReader.java b/lucene/src/java/org/apache/lucene/index/CompositeReader.java index 6e47e77300d..aec0bba5d8d 100644 --- a/lucene/src/java/org/apache/lucene/index/CompositeReader.java +++ b/lucene/src/java/org/apache/lucene/index/CompositeReader.java @@ -20,30 +20,26 @@ package org.apache.lucene.index; import org.apache.lucene.search.SearcherManager; // javadocs import org.apache.lucene.store.*; -/** 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. - +/** Instances of this reader type can only + be used to get stored fields from the underlying AtomicReaders, + but it is not possible to directly retrieve postings. To do that, get + the sub-readers via {@link #getSequentialSubReaders}. + +
IndexReader instances for indexes on disk are usually constructed
+ with a call to one of the static DirectoryReader,open() methods,
+ e.g. {@link DirectoryReader#open(Directory)}. {@link DirectoryReader} implements
+ the {@code CompositeReader} interface, it is not possible to directly get postings.
Concrete subclasses of IndexReader are usually constructed with a call to
one of the static open() methods, e.g. {@link
#open(Directory)}.
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 + 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: for backwards API compatibility, several methods are not listed - as abstract, but have no useful implementations in this base class and - instead always throw UnsupportedOperationException. Subclasses are - strongly encouraged to override these methods, but in many cases may not - need to. -
- -NOTE: {@link IndexReader} instances are completely thread safe, meaning multiple threads can call any of its methods, diff --git a/lucene/src/java/org/apache/lucene/index/DirectoryReader.java b/lucene/src/java/org/apache/lucene/index/DirectoryReader.java index 69c0cd848e4..75d97717418 100644 --- a/lucene/src/java/org/apache/lucene/index/DirectoryReader.java +++ b/lucene/src/java/org/apache/lucene/index/DirectoryReader.java @@ -31,10 +31,28 @@ import org.apache.lucene.store.Directory; import org.apache.lucene.store.IOContext; import org.apache.lucene.util.IOUtils; -/** - * An IndexReader which reads indexes with multiple segments. - * To get an instance of this reader use {@link #open(Directory)}. - */ +/** DirectoryReader is an implementation of {@link CompositeReader} + that can read indexes in a {@link Directory}. + +
DirectoryReader instances are usually constructed with a call to
+ one of the static open() methods, e.g. {@link
+ #open(Directory)}.
+
+
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: {@link
+ 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
+ Concrete subclasses of IndexReader are usually constructed with a call to
- one of the static There are two different types of IndexReaders:
+ IndexReader instances for indexes on disk are usually constructed
+ with a call to one of the static 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
+ 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: for backwards API compatibility, several methods are not listed
- as abstract, but have no useful implementations in this base class and
- instead always throw UnsupportedOperationException. Subclasses are
- strongly encouraged to override these methods, but in many cases may not
- need to.
- NOTE: {@link
IndexReader} instances are completely thread
safe, meaning multiple threads can call any of its methods,
IndexReader instance; use your own
+ (non-Lucene) objects instead.
+*/
public final class DirectoryReader extends BaseMultiReaderopen() methods, e.g. {@link
- #open(Directory)}.
+
+
+
+ DirectoryReader,open() methods,
+ e.g. {@link DirectoryReader#open(Directory)}. {@link DirectoryReader} implements
+ the {@link CompositeReader} interface, it is not possible to directly get postings.