org.apache.hadoop.mapreduce

类 MapContext<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>

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

类型参数:

KEYIN - the key input type to the Mapper

VALUEIN - the value input type to the Mapper

KEYOUT - the key output type from the Mapper

VALUEOUT - the value output type from the Mapper

所有已实现的接口:

Progressable

直接已知子类:

Mapper.Context

public class MapContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>
extends TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

The context that is given to the Mapper.

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
MapContext(Configuration conf, TaskAttemptID taskid, RecordReader<KEYIN,VALUEIN> reader, RecordWriter<KEYOUT,VALUEOUT> writer, OutputCommitter committer, StatusReporter reporter, InputSplit split)

方法概要

方法

限定符和类型	方法和说明
KEYIN	getCurrentKey() Get the current key.
VALUEIN	getCurrentValue() Get the current value.
InputSplit	getInputSplit() Get the input split for this map.
boolean	nextKeyValue() Advance to the next key, value pair, returning null if at end.

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

getCounter, getCounter, getOutputCommitter, getProgress, progress, setStatus, write

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

MapContext

public MapContext(Configuration conf,
          TaskAttemptID taskid,
          RecordReader<KEYIN,VALUEIN> reader,
          RecordWriter<KEYOUT,VALUEOUT> writer,
          OutputCommitter committer,
          StatusReporter reporter,
          InputSplit split)

方法详细资料

getInputSplit

public InputSplit getInputSplit()

Get the input split for this map.

getCurrentKey

public KEYIN getCurrentKey()
                    throws IOException,
                           InterruptedException

从类复制的说明: TaskInputOutputContext

Get the current key.

指定者:

getCurrentKey 在类中 TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

返回:

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

抛出:

IOException

InterruptedException

getCurrentValue

public VALUEIN getCurrentValue()
                        throws IOException,
                               InterruptedException

从类复制的说明: TaskInputOutputContext

Get the current value.

指定者:

getCurrentValue 在类中 TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

返回:

the value object that was read into

抛出:

IOException

InterruptedException

nextKeyValue

public boolean nextKeyValue()
                     throws IOException,
                            InterruptedException

从类复制的说明: TaskInputOutputContext

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

指定者:

nextKeyValue 在类中 TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>

返回:

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

抛出:

IOException

InterruptedException