新版MapReduce的API編程簡單模板

新版MapReduce的API編程簡單模板

import java.io.IOException;
import java.util.*;

import org.apache.Hadoop.conf.*;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.*;
import org.apache.hadoop.mapreduce.lib.output.*;
import org.apache.hadoop.util.*;

public class MyJob extends Configured implements Tool{
public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
String line = value.toString();
StringTokenizer tokenizer = new StringTokenizer(line," \t\n\r\f,.:?![]'`;");
while (tokenizer.hasMoreTokens()) {
word.set(tokenizer.nextToken());
context.write(word, one);
}
}
}

public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {
public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
int sum = 0;
while (values.iterator().hasNext()) {
sum += values.iterator().next().get();
}
context.write(key, new IntWritable(sum));
}
}

public int run(String[] args) throws Exception {
Configuration conf=getConf();

Job job= new Job(conf,"WordCount");
job.setJarByClass(MyJob.class);

FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));

job.setJobName("WordCount");
job.setMapperClass(Map.class);
job.setCombinerClass(Reduce.class);
job.setReducerClass(Reduce.class);

job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
System.exit(job.waitForCompletion(true)?0:1) ;
return 1;
}

public static void main(String[] args) throws Exception {
int res =ToolRunner.run(new Configuration(), new MyJob(), args);
System.exit(res);
}
}