Java tutorial
//package org.apache.hadoop.examples; /** * 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.StringTokenizer; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.examples.MultiFileWordCount.WordOffset; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.InputSplit; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.RecordReader; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.TaskAttemptContext; import org.apache.hadoop.mapreduce.lib.input.CombineFileRecordReader; import org.apache.hadoop.mapreduce.lib.input.CombineFileSplit; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.input.FileSplit; import org.apache.hadoop.mapreduce.lib.input.RHadoopInputFormat; import org.apache.hadoop.mapreduce.lib.input.LineRecordReader; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.util.GenericOptionsParser; import org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat; public class DateExample_Month { public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> { private final static IntWritable one = new IntWritable(1); private Text word = new Text(); public void map(Object key, Text value, Context context) throws IOException, InterruptedException { long startTime = System.nanoTime(); IsValidKeyFormat isv = new IsValidKeyFormat(); String strValue = value.toString().trim(); int keyIndex = strValue.indexOf("\t"); if (keyIndex == -1) return; String dateKey = strValue.substring(0, keyIndex); if (isv.isValidKey(dateKey)) { // No reduce jobs // O(n) Job on value String logValue = strValue.substring(keyIndex); for (int i = 0; i < logValue.length(); i++) ; //word.set(dateKey); //context.write(word, one); } runTimeMapper += System.nanoTime() - startTime; } } public static class IntSumReducer extends Reducer<Text, IntWritable, Text, IntWritable> { private IntWritable result = new IntWritable(); public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { int sum = 0; for (IntWritable val : values) { sum += val.get(); } result.set(sum); context.write(key, result); } } public static class IsValidKeyFormat extends RHadoopInputFormat { class Date { int year; int month; int day; int hour; int minutes; String msg; Date(String str) { if (str == null) return; String parts[] = str.split("/"); if (parts.length != 3) return; year = Integer.parseInt(parts[0]); month = Integer.parseInt(parts[1]); parts = parts[2].split("-"); if (parts.length != 3) return; day = Integer.parseInt(parts[0]); msg = parts[2]; parts = parts[1].split(":"); if (parts.length != 2) return; hour = Integer.parseInt(parts[0]); minutes = Integer.parseInt(parts[0]); } } @Override public boolean isValidKeyRange(String lower, String upper) { Date lowKey = new Date(lower); Date highKey = new Date(upper); int qmonth = 4; // April Logs only if (lowKey.year == highKey.year && lowKey.month <= qmonth && qmonth <= highKey.month) return true; if (lowKey.year == (highKey.year - 1) && lowKey.month <= qmonth) return true; if (lowKey.year == (highKey.year - 1) && qmonth <= highKey.month) return true; return false; } } public static void main(String[] args) throws Exception { Configuration conf = new Configuration(); String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs(); if (otherArgs.length != 2) { System.err.println("Usage: wordcount <in> <out>"); System.exit(2); } Job job = new Job(conf, "word count fs"); job.setJarByClass(DateExample_Month.class); job.setMapperClass(TokenizerMapper.class); job.setCombinerClass(IntSumReducer.class); job.setReducerClass(IntSumReducer.class); job.setOutputKeyClass(Text.class); job.setOutputValueClass(IntWritable.class); job.setInputFormatClass(IsValidKeyFormat.class); FileInputFormat.addInputPath(job, new Path(otherArgs[0])); FileOutputFormat.setOutputPath(job, new Path(otherArgs[1])); System.exit(job.waitForCompletion(true) ? 0 : 1); } }