<dependency><groupId>org.apache.hadoop</groupId><artifactId>hadoop-client</artifactId><version>2.7.0</version>
</dependency>

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;public class WordCount {public static class TokenizerMapperextends 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 IntSumReducerextends 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 conf = new Configuration();Job job = Job.getInstance(conf, "word count");job.setJarByClass(WordCount.class);job.setMapperClass(TokenizerMapper.class);job.setCombinerClass(IntSumReducer.class);job.setReducerClass(IntSumReducer.class);job.setOutputKeyClass(Text.class);job.setOutputValueClass(IntWritable.class);FileInputFormat.addInputPath(job, new Path(args[0]));FileOutputFormat.setOutputPath(job, new Path(args[1]));System.exit(job.waitForCompletion(true) ? 0 : 1);}
}

mvn clean install

<configuration><property><name>fs.defaultFS</name><value>hdfs://master:9000/</value></property><property><name>hadoop.tmp.dir</name><value>file:/home/localadmin/filedata</value></property>
</configuration>

 bin/hadoop fs -ls /

bin/hadoop fs -put /home/localadmin/filedata/infile/bin/hadoop fs -put /home/localadmin/filedata/infile/file01bin/hadoop fs -put /home/localadmin/filedata/infile/file02

# bin/hadoop fs -ls /home/localadmin/filedata/input
Found 2 items
-rw-r--r-- 3 root supergroup 22 2015-12-25 13:56 /home/localadmin/filedata/input/file01
-rw-r--r-- 3 root supergroup 28 2015-12-25 13:56 /home/localadmin/filedata/input/file02

hadoop jar wc.jar com.nonobank.hadoop.WordCount ../filedata/input/ ../filedata/output/