| /** |
| * 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.examples; |
| |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Map.Entry; |
| |
| import org.apache.hadoop.io.Text; |
| import org.apache.hadoop.mapreduce.Job; |
| import org.apache.hadoop.mapreduce.lib.aggregate.ValueAggregatorBaseDescriptor; |
| import org.apache.hadoop.mapreduce.lib.aggregate.ValueAggregatorJob; |
| |
| /** |
| * This is an example Aggregated Hadoop Map/Reduce application. Computes the |
| * histogram of the words in the input texts. |
| * |
| * To run: bin/hadoop jar hadoop-*-examples.jar aggregatewordhist <i>in-dir</i> |
| * <i>out-dir</i> <i>numOfReducers</i> textinputformat |
| * |
| */ |
| public class AggregateWordHistogram { |
| |
| public static class AggregateWordHistogramPlugin |
| extends ValueAggregatorBaseDescriptor { |
| |
| /** |
| * Parse the given value, generate an aggregation-id/value pair per word. |
| * The ID is of type VALUE_HISTOGRAM, with WORD_HISTOGRAM as the real id. |
| * The value is WORD\t1. |
| * |
| * @return a list of the generated pairs. |
| */ |
| @Override |
| public ArrayList<Entry<Text, Text>> generateKeyValPairs(Object key, |
| Object val) { |
| String words[] = val.toString().split(" |\t"); |
| ArrayList<Entry<Text, Text>> retv = new ArrayList<Entry<Text, Text>>(); |
| for (int i = 0; i < words.length; i++) { |
| Text valCount = new Text(words[i] + "\t" + "1"); |
| Entry<Text, Text> en = generateEntry(VALUE_HISTOGRAM, "WORD_HISTOGRAM", |
| valCount); |
| retv.add(en); |
| } |
| return retv; |
| } |
| |
| } |
| |
| /** |
| * The main driver for word count map/reduce program. Invoke this method to |
| * submit the map/reduce job. |
| * |
| * @throws IOException |
| * When there is communication problems with the job tracker. |
| */ |
| @SuppressWarnings("unchecked") |
| public static void main(String[] args) |
| throws IOException, InterruptedException, ClassNotFoundException { |
| Job job = ValueAggregatorJob.createValueAggregatorJob(args |
| , new Class[] {AggregateWordHistogramPlugin.class}); |
| job.setJarByClass(AggregateWordCount.class); |
| int ret = job.waitForCompletion(true) ? 0 : 1; |
| System.exit(ret); |
| } |
| } |