/*
* 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.writers;
import java.io.Writer;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.jena.atlas.io.AWriter;
import org.apache.jena.atlas.io.Writer2;
import org.apache.jena.graph.Node ;
import org.apache.jena.hadoop.rdf.types.AbstractNodeTupleWritable;
import org.apache.jena.riot.out.NodeFormatter;
import org.apache.jena.riot.out.NodeFormatterNT;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* An abstract implementation of a record writer that writes records to a line
* based tuple formats.
* <p>
* The implementation only writes the value portion of the key value pair since
* it is the value portion that is used to convey the node tuples
* </p>
*
*
* @param <TKey>
* Key type
* @param <TValue>
* Tuple type
* @param <T>
* Writable node tuple type
*
*/
public abstract class AbstractLineBasedNodeTupleWriter<TKey, TValue, T extends AbstractNodeTupleWritable<TValue>> extends
RecordWriter<TKey, T> {
/**
* Default separator written between nodes
*/
public static final String DEFAULT_SEPARATOR = " ";
/**
* Default terminator written at the end of each line
*/
public static final String DEFAULT_TERMINATOR = ".";
private static final Logger log = LoggerFactory.getLogger(AbstractLineBasedNodeTupleWriter.class);
private AWriter writer;
private NodeFormatter formatter;
/**
* Creates a new tuple writer using the default NTriples node formatter
*
* @param writer
* Writer
*/
public AbstractLineBasedNodeTupleWriter(Writer writer) {
this(writer, new NodeFormatterNT());
}
/**
* Creates a new tuple writer
*
* @param writer
* Writer
* @param formatter
* Node formatter
*/
public AbstractLineBasedNodeTupleWriter(Writer writer, NodeFormatter formatter) {
if (writer == null)
throw new NullPointerException("writer cannot be null");
if (formatter == null)
throw new NullPointerException("formatter cannot be null");
this.formatter = formatter;
this.writer = Writer2.wrap(writer);
}
@Override
public void write(TKey key, T value) {
log.debug("write({}={})", key, value);
Node[] ns = this.getNodes(value);
String sep = this.getSeparator();
NodeFormatter formatter = this.getNodeFormatter();
for (int i = 0; i < ns.length; i++) {
formatter.format(this.writer, ns[i]);
this.writer.print(sep);
}
this.writer.println(this.getTerminator());
this.writer.flush();
}
/**
* Gets the nodes of the tuple in the order they should be written
*
* @param tuple
* Tuple
* @return Nodes
*/
protected abstract Node[] getNodes(T tuple);
/**
* Gets the node formatter to use for formatting nodes
*
* @return Node formatter
*/
protected NodeFormatter getNodeFormatter() {
return this.formatter;
}
/**
* Gets the separator that is written between nodes
*
* @return Separator
*/
protected String getSeparator() {
return DEFAULT_SEPARATOR;
}
/**
* Gets the terminator that is written at the end of each tuple
*
* @return Terminator
*/
protected String getTerminator() {
return DEFAULT_TERMINATOR;
}
@Override
public void close(TaskAttemptContext context) {
log.debug("close({})", context);
writer.close();
}
}