org.apache.hadoop.mapred.lib
Class TokenCountMapper<K>
java.lang.Object
org.apache.hadoop.mapred.MapReduceBase
org.apache.hadoop.mapred.lib.TokenCountMapper<K>
- All Implemented Interfaces:
- Closeable, JobConfigurable, Mapper<K,Text,Text,LongWritable>
@InterfaceAudience.Public
@InterfaceStability.Stable
public class TokenCountMapper<K>
- extends MapReduceBase
- implements Mapper<K,Text,Text,LongWritable>
A Mapper
that maps text values into pairs. Uses
StringTokenizer
to break text into tokens.
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
TokenCountMapper
public TokenCountMapper()
map
public void map(K key,
Text value,
OutputCollector<Text,LongWritable> output,
Reporter reporter)
throws IOException
- Description copied from interface:
Mapper
- Maps a single input key/value pair into an intermediate key/value pair.
Output pairs need not be of the same types as input pairs. A given
input pair may map to zero or many output pairs. Output pairs are
collected with calls to
OutputCollector.collect(Object,Object)
.
Applications can use the Reporter
provided to report progress
or just indicate that they are alive. In scenarios where the application
takes significant amount of time to process individual key/value
pairs, this is crucial since the framework might assume that the task has
timed-out and kill that task. The other way of avoiding this is to set
mapreduce.task.timeout to a high-enough value (or even zero for no
time-outs).
- Specified by:
map
in interface Mapper<K,Text,Text,LongWritable>
- Parameters:
key
- the input key.value
- the input value.output
- collects mapped keys and values.reporter
- facility to report progress.
- Throws:
IOException
Copyright © 2014 Apache Software Foundation. All Rights Reserved.