hadoop之hello world
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//初学hadoop ,这是第一个例子wordCount
import java.io.IOException ;
import java.util.StringTokenizer;
import org.apach.hadoop.conf.*;
import org.apach.hadoop.fs.*;
import org.apach.hadoop.io.*;
import org.apach.hadoop.mapreduce.*;
import org.apach.hadoop.mapreduce.lib.input.*;
import org.apach.hadoop.mapreduce.lib..output.*;
import org.apach.hadoop.util.Tool;
import org.apach.hadoop.util.ToolRunner;
/*
* author : guigu
* time : 2014-10-17
*/
public clss NewWordCount 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 , InterruptException{
String line = value.toString();
StringTokenizer tokenizer = new StringTokenizer(line);
while(tokenizer.hasMoreTokens()){
word.set(tokenizer.nextToken());
context.write(word, one);
}
}
}
public static class Reduce extends Reduce (Text , IntWritable,Text, IntWritable>{
public void reduce (Text key, Interable<IntWritable> values, org.apache.hadoop.mapreduce.Reduce.Context context)
throws IOException , InterruptedException{
int sum = 0;
for (IntWritable val :values) {
sum += val.get();
}
context.write(key, new IntWritable(sum));
}
}
public static void main(String[] args) throw Exception{
int ret = ToolRunner.run(new New NewWordCount(), args);
System.exit(ret);
}
public int run (String[] args) throws Exception {
Job job = new Job(getConf());
job.setJarByClass(NewWordCount.class);
job.setJobName("newwordcount");
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
job.setMapperClass(Map.class);
job.setReduceClass(Reduce.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileInputFormat.setInputPaths(job, new Path(args[0]);
FileOutputFormat.setOutputPath(job, new Path(args[1]);
boolean success = job.waitForCompletion(true);
return success ? 0 : 1 ;
}
}
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