Java tutorial
/* * Copyright 2011 10gen Inc. * * 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 com.mongodb.hadoop.examples.treasury; import com.mongodb.hadoop.io.BSONWritable; import com.mongodb.hadoop.mapred.MongoInputFormat; import com.mongodb.hadoop.mapred.MongoOutputFormat; import com.mongodb.hadoop.util.MongoConfigUtil; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.io.DoubleWritable; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.mapred.JobClient; import org.apache.hadoop.mapred.JobConf; import org.apache.hadoop.mapred.MapReduceBase; import org.apache.hadoop.mapred.Mapper; import org.apache.hadoop.mapred.OutputCollector; import org.apache.hadoop.mapred.Reducer; import org.apache.hadoop.mapred.Reporter; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.bson.BasicBSONObject; import java.io.IOException; import java.util.Date; import java.util.Iterator; /** * The treasury yield xml config object. */ public class TreasuryYieldXMLConfigV2 extends Configured implements Tool { private static final Log LOG = LogFactory.getLog(TreasuryYieldXMLConfigV2.class); static class TreasuryYieldMapperV2 extends MapReduceBase implements Mapper<BSONWritable, BSONWritable, IntWritable, DoubleWritable> { @Override @SuppressWarnings("deprecation") public void map(final BSONWritable key, final BSONWritable value, final OutputCollector<IntWritable, DoubleWritable> output, final Reporter reporter) throws IOException { final int year = ((Date) value.getDoc().get("_id")).getYear() + 1900; double bid10Year = ((Number) value.getDoc().get("bc10Year")).doubleValue(); output.collect(new IntWritable(year), new DoubleWritable(bid10Year)); } } static class TreasuryYieldReducerV2 extends MapReduceBase implements Reducer<IntWritable, DoubleWritable, IntWritable, BSONWritable> { @Override public void reduce(final IntWritable key, final Iterator<DoubleWritable> values, final OutputCollector<IntWritable, BSONWritable> output, final Reporter reporter) throws IOException { int count = 0; double sum = 0; while (values.hasNext()) { DoubleWritable value = values.next(); sum += value.get(); count++; } final double avg = sum / count; LOG.info("V2: Average 10 Year Treasury for " + key.get() + " was " + avg); BasicBSONObject outputObj = new BasicBSONObject(); outputObj.put("count", count); outputObj.put("avg", avg); outputObj.put("sum", sum); output.collect(key, new BSONWritable(outputObj)); } } public int run(final String[] args) throws Exception { final Configuration conf = getConf(); final JobConf job = new JobConf(conf); job.setReducerClass(TreasuryYieldReducerV2.class); job.setMapperClass(TreasuryYieldMapperV2.class); job.setOutputFormat(MongoOutputFormat.class); job.setOutputKeyClass(MongoConfigUtil.getOutputKey(conf)); job.setOutputValueClass(MongoConfigUtil.getOutputValue(conf)); job.setMapOutputKeyClass(MongoConfigUtil.getMapperOutputKey(conf)); job.setMapOutputValueClass(MongoConfigUtil.getMapperOutputValue(conf)); job.setInputFormat(MongoInputFormat.class); JobClient.runJob(job); return 0; } public static void main(final String[] args) throws Exception { ToolRunner.run(new TreasuryYieldXMLConfigV2(), args); } }