/**
* 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.hadoop.mapreduce.lib.map;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
/** A {@link Mapper} that extracts text matching a regular expression. */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class RegexMapper<K> extends Mapper<K, Text, Text, LongWritable> {
public static String PATTERN = "mapreduce.mapper.regex";
public static String GROUP = "mapreduce.mapper.regexmapper..group";
private Pattern pattern;
private int group;
public void setup(Context context) {
Configuration conf = context.getConfiguration();
pattern = Pattern.compile(conf.get(PATTERN));
group = conf.getInt(GROUP, 0);
}
public void map(K key, Text value,
Context context)
throws IOException, InterruptedException {
String text = value.toString();
Matcher matcher = pattern.matcher(text);
while (matcher.find()) {
context.write(new Text(matcher.group(group)), new LongWritable(1));
}
}
}