AggregateWordCount.java
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上传日期:2018-01-08
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- /**
- * 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.StringTokenizer;
- import java.util.Map.Entry;
- import org.apache.hadoop.io.Text;
- import org.apache.hadoop.mapred.JobClient;
- import org.apache.hadoop.mapred.JobConf;
- import org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorBaseDescriptor;
- import org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJob;
- /**
- * This is an example Aggregated Hadoop Map/Reduce application. It reads the
- * text input files, breaks each line into words and counts them. The output is
- * a locally sorted list of words and the count of how often they occurred.
- *
- * To run: bin/hadoop jar hadoop-*-examples.jar aggregatewordcount <i>in-dir</i>
- * <i>out-dir</i> <i>numOfReducers</i> textinputformat
- *
- */
- public class AggregateWordCount {
- public static class WordCountPlugInClass extends
- ValueAggregatorBaseDescriptor {
- @Override
- public ArrayList<Entry<Text, Text>> generateKeyValPairs(Object key,
- Object val) {
- String countType = LONG_VALUE_SUM;
- ArrayList<Entry<Text, Text>> retv = new ArrayList<Entry<Text, Text>>();
- String line = val.toString();
- StringTokenizer itr = new StringTokenizer(line);
- while (itr.hasMoreTokens()) {
- Entry<Text, Text> e = generateEntry(countType, itr.nextToken(), ONE);
- if (e != null) {
- retv.add(e);
- }
- }
- 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 {
- JobConf conf = ValueAggregatorJob.createValueAggregatorJob(args
- , new Class[] {WordCountPlugInClass.class});
-
- JobClient.runJob(conf);
- }
- }