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import java.io.IOException;import java.util.StringTokenizer;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.Mapper;import org.apache.hadoop.mapreduce.Reducer;import
org.apache.hadoop.mapreduce.lib.input.FileInputFormat;import
org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;import
org.apache.hadoop.util.GenericOptionsParser; public
class Test{ 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 { StringTokenizer itr = new
StringTokenizer(value.toString()); while
(itr.hasMoreTokens()) { word.set(itr.nextToken()); context.write(word, one); } } } 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 void main(String[] args) throws
Exception { //configuration for the job Configuration conf = new
Configuration(); conf.addResource(new
Path("/usr/local/hadoop/etc/hadoop/core-site.xml")); conf.addResource(new
Path("/usr/local/hadoop/etc/hadoop/hdfs-site.xml")); Job job = new
Job(conf, "word count"); job.setJarByClass(Test.class); //set the mapper, combiner, reducer job.setMapperClass(TokenizerMapper.class); job.setCombinerClass(IntSumReducer.class); job.setReducerClass(IntSumReducer.class); //the key is type of Text job.setOutputKeyClass(Text.class); //the value is type of IntWritable job.setOutputValueClass(IntWritable.class); String[] otherArgs = new
GenericOptionsParser(conf, args).getRemainingArgs(); otherArgs = new
String[2]; otherArgs[0]="/input"; otherArgs[1]="/output"; if
(otherArgs.length != 2) { System.err.println("Usage: wordcount <in> <out>"); System.exit(2); } FileInputFormat.addInputPath(job, new
Path(otherArgs[0])); FileOutputFormat.setOutputPath(job, new
Path(otherArgs[1])); System.out.println("Hello World"); System.exit(job.waitForCompletion(true) ? 0
: 1); }} |
Hadoop WordCount 小析,布布扣,bubuko.com
原文：http://www.cnblogs.com/rambot/p/3622130.html