/*
* 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.
*/
package org.apache.jena.hadoop.rdf.io.output;
import java.io.IOException;
import java.io.Writer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.jena.hadoop.rdf.io.output.writers.QuadsToTriplesWriter;
import org.apache.jena.hadoop.rdf.io.registry.HadoopRdfIORegistry;
import org.apache.jena.hadoop.rdf.types.QuadWritable;
import org.apache.jena.riot.Lang;
import org.apache.jena.riot.RDFLanguages;
import org.apache.jena.sparql.core.Quad ;
/**
* An output format for RDF triples/quads that dynamically selects the
* appropriate triple/quad writer to use based on the file extension of the
* output file.
* <p>
* For example this is useful when the output format may be controlled by a user
* supplied filename i.e. the desired RDF output format is not precisely known
* in advance.
* </p>
* <h3>Warning</h3>
* <p>
* Where the format is determined to be triples the quads are converted into
* triples are thus will lose any graph information that might be carried.
* </p>
*
* @param <TKey>
* Key type
*/
public abstract class TriplesOrQuadsOutputFormat<TKey> extends AbstractNodeTupleOutputFormat<TKey, Quad, QuadWritable> {
@Override
protected RecordWriter<TKey, QuadWritable> getRecordWriter(Writer writer, Configuration config, Path outputPath)
throws IOException {
Lang lang = RDFLanguages.filenameToLang(outputPath.getName());
if (lang == null)
throw new IOException("There is no registered RDF language for the output file " + outputPath.toString());
if (!RDFLanguages.isQuads(lang) && !RDFLanguages.isTriples(lang))
throw new IOException(lang.getName() + " is not a RDF triples/quads format");
if (HadoopRdfIORegistry.hasQuadWriter(lang)) {
// Supports quads directly
return HadoopRdfIORegistry.<TKey> createQuadWriter(lang, writer, config);
} else {
// Try to create a triples writer and wrap downwards from quads
// This will throw an error if a triple writer is not available
return new QuadsToTriplesWriter<TKey>(HadoopRdfIORegistry.<TKey> createTripleWriter(lang, writer, config));
}
}
}