public class PipeMapper extends PipeMapRed implements Mapper
LOG, outerrThreadsThrowable
构造器和说明 |
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PipeMapper() |
限定符和类型 | 方法和说明 |
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void |
close() |
void |
configure(JobConf job)
Initializes a new instance from a
JobConf . |
byte[] |
getFieldSeparator()
Returns the field separator to be used.
|
byte[] |
getInputSeparator()
Returns the input separator to be used.
|
int |
getNumOfKeyFields()
Returns the number of key fields.
|
void |
map(Object key,
Object value,
OutputCollector output,
Reporter reporter)
Maps a single input key/value pair into an intermediate key/value pair.
|
getClientInput, getClientOutput, getConfiguration, getContext, mapRedFinished
public void configure(JobConf job)
JobConfigurable
JobConf
.configure
在接口中 JobConfigurable
configure
在类中 PipeMapRed
job
- the configurationpublic void map(Object key, Object value, OutputCollector output, Reporter reporter) throws IOException
Mapper
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 an insignificant 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
mapred.task.timeout to a high-enough value (or even zero for no
time-outs).
map
在接口中 Mapper
key
- the input key.value
- the input value.output
- collects mapped keys and values.reporter
- facility to report progress.IOException
public void close()
close
在接口中 Closeable
close
在接口中 AutoCloseable
public byte[] getInputSeparator()
PipeMapRed
getInputSeparator
在类中 PipeMapRed
public byte[] getFieldSeparator()
PipeMapRed
getFieldSeparator
在类中 PipeMapRed
public int getNumOfKeyFields()
PipeMapRed
getNumOfKeyFields
在类中 PipeMapRed
Copyright © 2009 The Apache Software Foundation