org.apache.lucene.index.StoredFieldVisitor Maven / Gradle / Ivy
package org.apache.lucene.index;
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.DocumentStoredFieldVisitor;
/**
* Expert: provides a low-level means of accessing the stored field
* values in an index. See {@link IndexReader#document(int,
* StoredFieldVisitor)}.
*
* NOTE: a {@code StoredFieldVisitor} implementation
* should not try to load or visit other stored documents in
* the same reader because the implementation of stored
* fields for most codecs is not reeentrant and you will see
* strange exceptions as a result.
*
*
See {@link DocumentStoredFieldVisitor}, which is a
* StoredFieldVisitor that builds the
* {@link Document} containing all stored fields. This is
* used by {@link IndexReader#document(int)}.
*
* @lucene.experimental */
public abstract class StoredFieldVisitor {
/** Sole constructor. (For invocation by subclass
* constructors, typically implicit.) */
protected StoredFieldVisitor() {
}
/** Process a binary field.
* @param value newly allocated byte array with the binary contents.
*/
public void binaryField(FieldInfo fieldInfo, byte[] value) throws IOException {
}
/** Process a string field; the provided byte[] value is a UTF-8 encoded string value. */
public void stringField(FieldInfo fieldInfo, byte[] value) throws IOException {
}
/** Process a int numeric field. */
public void intField(FieldInfo fieldInfo, int value) throws IOException {
}
/** Process a long numeric field. */
public void longField(FieldInfo fieldInfo, long value) throws IOException {
}
/** Process a float numeric field. */
public void floatField(FieldInfo fieldInfo, float value) throws IOException {
}
/** Process a double numeric field. */
public void doubleField(FieldInfo fieldInfo, double value) throws IOException {
}
/**
* Hook before processing a field.
* Before a field is processed, this method is invoked so that
* subclasses can return a {@link Status} representing whether
* they need that particular field or not, or to stop processing
* entirely.
*/
public abstract Status needsField(FieldInfo fieldInfo) throws IOException;
/**
* Enumeration of possible return values for {@link #needsField}.
*/
public static enum Status {
/** YES: the field should be visited. */
YES,
/** NO: don't visit this field, but continue processing fields for this document. */
NO,
/** STOP: don't visit this field and stop processing any other fields for this document. */
STOP
}
}