我有一个 MapReduce 程序如下
import java.io.IOException;
import java.util.Iterator;
import java.util.StringTokenizer;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.KeyValueTextInputFormat;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.TextOutputFormat;
public class Sample {
public static class SampleMapper extends MapReduceBase implements
Mapper<Text, Text, Text, Text> {
private Text word = new Text();
@Override
public void map(Text key, Text value,
OutputCollector<Text, Text> output, Reporter reporter)
throws IOException {
StringTokenizer itr = new StringTokenizer(value.toString(),",");
while (itr.hasMoreTokens()) {
word.set(itr.nextToken());
output.collect(key, word);
}
}
}
public static class SampleReducer extends MapReduceBase implements
Reducer<Text, Text, Text, Text> {
private Text result = new Text();
@Override
public void reduce(Text key, Iterator<Text> values,
OutputCollector<Text, Text> output, Reporter reporter)
throws IOException {
StringBuffer aggregation = new StringBuffer();
while (values.hasNext()) {
aggregation.append("|" + values.next().toString());
}
result.set(aggregation.toString());
output.collect(key, result);
}
}
public static void main(String args[]) throws IOException {
JobConf conf = new JobConf(Sample.class);
conf.setJobName("Sample");
conf.setMapperClass(SampleMapper.class);
conf.setReducerClass(SampleReducer.class);
conf.setOutputKeyClass(Text.class);
conf.setOutputValueClass(Text.class);
conf.setInputFormat(KeyValueTextInputFormat.class);
conf.setOutputFormat(TextOutputFormat.class);
FileInputFormat.setInputPaths(conf, new Path(args[0]));
FileOutputFormat.setOutputPath(conf, new Path(args[1]));
JobClient.runJob(conf);
}
}
我已经制作了罐子,并且一直在尝试获得输出。但是正在创建的输出文件是空的。
我正在使用以下命令来运行作业
hadoop jar mapreduce.jar Sample /tmp/input tmp/output
mapreduce.jar 是我打包的jar,我的输入文件就像
1 a,b,c
2 e,f
1 x,y,z
2 g
预期产出
1 a|b|c|x|y|z
2 e|f|g