org.apache.hadoop.mapreduce

类 TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

java.lang.Object

org.apache.hadoop.mapreduce.JobContext

org.apache.hadoop.mapreduce.TaskAttemptContext

org.apache.hadoop.mapreduce.TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

类型参数:

KEYIN - the input key type for the task

VALUEIN - the input value type for the task

KEYOUT - the output key type for the task

VALUEOUT - the output value type for the task

所有已实现的接口:

Progressable

直接已知子类:

MapContext, ReduceContext

public abstract class TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>
extends TaskAttemptContext
implements Progressable

A context object that allows input and output from the task. It is only supplied to the Mapper or Reducer.

字段概要

从类继承的字段 org.apache.hadoop.mapreduce.JobContext

CACHE_ARCHIVES_VISIBILITIES, CACHE_FILE_VISIBILITIES, COMBINE_CLASS_ATTR, conf, credentials, INPUT_FORMAT_CLASS_ATTR, JOB_ACL_MODIFY_JOB, JOB_ACL_VIEW_JOB, JOB_CANCEL_DELEGATION_TOKEN, JOB_NAMENODES, MAP_CLASS_ATTR, OUTPUT_FORMAT_CLASS_ATTR, PARTITIONER_CLASS_ATTR, REDUCE_CLASS_ATTR, ugi, USER_LOG_RETAIN_HOURS

构造器概要

构造器

构造器和说明
TaskInputOutputContext(Configuration conf, TaskAttemptID taskid, RecordWriter<KEYOUT,VALUEOUT> output, OutputCommitter committer, StatusReporter reporter)

方法概要

方法

限定符和类型	方法和说明
Counter	getCounter(Enum<?> counterName)
Counter	getCounter(String groupName, String counterName)
abstract KEYIN	getCurrentKey() Get the current key.
abstract VALUEIN	getCurrentValue() Get the current value.
OutputCommitter	getOutputCommitter()
float	getProgress()
abstract boolean	nextKeyValue() Advance to the next key, value pair, returning null if at end.
void	progress() Report progress.
void	setStatus(String status) Set the current status of the task to the given string.
void	write(KEYOUT key, VALUEOUT value) Generate an output key/value pair.

从类继承的方法 org.apache.hadoop.mapreduce.TaskAttemptContext

getStatus, getTaskAttemptID

从类继承的方法 org.apache.hadoop.mapreduce.JobContext

getCombinerClass, getConfiguration, getCredentials, getGroupingComparator, getInputFormatClass, getJar, getJobID, getJobName, getMapOutputKeyClass, getMapOutputValueClass, getMapperClass, getNumReduceTasks, getOutputFormatClass, getOutputKeyClass, getOutputValueClass, getPartitionerClass, getReducerClass, getSortComparator, getWorkingDirectory

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

TaskInputOutputContext

public TaskInputOutputContext(Configuration conf,
                      TaskAttemptID taskid,
                      RecordWriter<KEYOUT,VALUEOUT> output,
                      OutputCommitter committer,
                      StatusReporter reporter)

方法详细资料

nextKeyValue

public abstract boolean nextKeyValue()
                              throws IOException,
                                     InterruptedException

Advance to the next key, value pair, returning null if at end.

返回:

the key object that was read into, or null if no more

抛出:

IOException

InterruptedException

getCurrentKey

public abstract KEYIN getCurrentKey()
                             throws IOException,
                                    InterruptedException

Get the current key.

返回:

the current key object or null if there isn't one

抛出:

IOException

InterruptedException

getCurrentValue

public abstract VALUEIN getCurrentValue()
                                 throws IOException,
                                        InterruptedException

Get the current value.

返回:

the value object that was read into

抛出:

IOException

InterruptedException

write

public void write(KEYOUT key,
         VALUEOUT value)
           throws IOException,
                  InterruptedException

Generate an output key/value pair.

抛出:

IOException

InterruptedException

getCounter

public Counter getCounter(Enum<?> counterName)

getCounter

public Counter getCounter(String groupName,
                 String counterName)

progress

public void progress()

从类复制的说明: TaskAttemptContext

Report progress. The subtypes actually do work in this method.

指定者:

progress 在接口中 Progressable

覆盖:

progress 在类中 TaskAttemptContext

getProgress

public float getProgress()

setStatus

public void setStatus(String status)

从类复制的说明: TaskAttemptContext

Set the current status of the task to the given string.

覆盖:

setStatus 在类中 TaskAttemptContext

getOutputCommitter

public OutputCommitter getOutputCommitter()