/*
* Copyright 2002-2005 the original author or authors.
*
* Licensed 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.
*/
package org.springmodules.lucene.index.core;
import java.io.IOException;
import org.apache.lucene.index.IndexWriter;
/**
* Generic callback interface for code that operates on a Lucene IndexWriter.
* Allows to execute any number of operations on a single IndexWriter.
*
* <p>This is particularly useful for delegating to existing data access code
* that expects an IndexWriter to work on and throws IOException. For newly
* written code, it is strongly recommended to use LuceneIndexTemplate's more
* specific methods.
*
* @author Brian McCallister
* @author Thierry Templier
* @see org.springmodules.lucene.index.core.LuceneIndexTemplate
*/
public interface WriterCallback {
/**
* Gets called by <code>LuceneIndexTemplate.write</code> with an active Lucene
* IndexWriter. Does not need to care about activating or closing the IndexWriter.
*
* <p>Allows for returning a result object created within the callback, i.e.
* a domain object or a collection of domain objects. A thrown
* RuntimeException is treated as application exception: it gets propagated
* to the caller of the template.
*
* @param writer an active IndexWriter
* @return a result object, or null if none
* @throws IOException if thrown by a Lucene method, to be auto-converted
* to a LuceneIndexAccessException
*/
Object doWithWriter(IndexWriter writer) throws IOException;
}