org.apache.hadoop.mapred.lib

类 DelegatingMapper<K1,V1,K2,V2>

java.lang.Object

org.apache.hadoop.mapred.lib.DelegatingMapper<K1,V1,K2,V2>

所有已实现的接口:

Closeable, AutoCloseable, JobConfigurable, Mapper<K1,V1,K2,V2>

public class DelegatingMapper<K1,V1,K2,V2>
extends Object
implements Mapper<K1,V1,K2,V2>

An Mapper that delegates behaviour of paths to multiple other mappers.

另请参阅:

MultipleInputs.addInputPath(JobConf, Path, Class, Class)

构造器概要

构造器

构造器和说明
DelegatingMapper()

方法概要

方法

限定符和类型	方法和说明
void	close()
void	configure(JobConf conf) Initializes a new instance from a JobConf.
void	map(K1 key, V1 value, OutputCollector<K2,V2> outputCollector, Reporter reporter) Maps a single input key/value pair into an intermediate key/value pair.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

DelegatingMapper

public DelegatingMapper()

方法详细资料

map

public void map(K1 key,
       V1 value,
       OutputCollector<K2,V2> outputCollector,
       Reporter reporter)
         throws IOException

从接口复制的说明: 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 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).

指定者:

map 在接口中 Mapper<K1,V1,K2,V2>

参数:

key - the input key.

value - the input value.

outputCollector - collects mapped keys and values.

reporter - facility to report progress.

抛出:

IOException

configure

public void configure(JobConf conf)

从接口复制的说明: JobConfigurable

Initializes a new instance from a JobConf.

指定者:

configure 在接口中 JobConfigurable

参数:

conf - the configuration

close

public void close()
           throws IOException

指定者:

close 在接口中 Closeable

指定者:

close 在接口中 AutoCloseable

抛出:

IOException