org.apache.hadoop.mapreduce.lib.input

类 CombineFileRecordReader<K,V>

java.lang.Object

org.apache.hadoop.mapreduce.RecordReader<K,V>

org.apache.hadoop.mapreduce.lib.input.CombineFileRecordReader<K,V>

所有已实现的接口:

Closeable, AutoCloseable

@InterfaceAudience.Public
@InterfaceStability.Stable
public class CombineFileRecordReader<K,V>
extends RecordReader<K,V>

A generic RecordReader that can hand out different recordReaders for each chunk in a CombineFileSplit. A CombineFileSplit can combine data chunks from multiple files. This class allows using different RecordReaders for processing these data chunks from different files.

另请参阅:

CombineFileSplit

字段概要

字段

限定符和类型	字段和说明
protected TaskAttemptContext	context
protected RecordReader<K,V>	curReader
protected FileSystem	fs
protected int	idx
protected long	progress
protected Class<? extends RecordReader<K,V>>	rrClass
protected Constructor<? extends RecordReader<K,V>>	rrConstructor
protected CombineFileSplit	split

构造器概要

构造器

构造器和说明
CombineFileRecordReader(CombineFileSplit split, TaskAttemptContext context, Class<? extends RecordReader<K,V>> rrClass) A generic RecordReader that can hand out different recordReaders for each chunk in the CombineFileSplit.

方法概要

方法

限定符和类型	方法和说明
void	close() Close the record reader.
K	getCurrentKey() Get the current key
V	getCurrentValue() Get the current value.
float	getProgress() return progress based on the amount of data processed so far.
void	initialize(InputSplit split, TaskAttemptContext context) Called once at initialization.
protected boolean	initNextRecordReader() Get the record reader for the next chunk in this CombineFileSplit.
boolean	nextKeyValue() Read the next key, value pair.

从类继承的方法 java.lang.Object

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

字段详细资料

split

protected CombineFileSplit split

rrClass

protected Class<? extends RecordReader<K,V>> rrClass

rrConstructor

protected Constructor<? extends RecordReader<K,V>> rrConstructor

fs

protected FileSystem fs

context

protected TaskAttemptContext context

idx

protected int idx

progress

protected long progress

curReader

protected RecordReader<K,V> curReader

构造器详细资料

CombineFileRecordReader

public CombineFileRecordReader(CombineFileSplit split,
                       TaskAttemptContext context,
                       Class<? extends RecordReader<K,V>> rrClass)
                        throws IOException

A generic RecordReader that can hand out different recordReaders for each chunk in the CombineFileSplit.

抛出:

IOException

方法详细资料

initialize

public void initialize(InputSplit split,
              TaskAttemptContext context)
                throws IOException,
                       InterruptedException

从类复制的说明: RecordReader

Called once at initialization.

指定者:

initialize 在类中 RecordReader<K,V>

参数:

split - the split that defines the range of records to read

context - the information about the task

抛出:

IOException

InterruptedException

nextKeyValue

public boolean nextKeyValue()
                     throws IOException,
                            InterruptedException

从类复制的说明: RecordReader

Read the next key, value pair.

指定者:

nextKeyValue 在类中 RecordReader<K,V>

返回:

true if a key/value pair was read

抛出:

IOException

InterruptedException

getCurrentKey

public K getCurrentKey()
                throws IOException,
                       InterruptedException

从类复制的说明: RecordReader

Get the current key

指定者:

getCurrentKey 在类中 RecordReader<K,V>

返回:

the current key or null if there is no current key

抛出:

IOException

InterruptedException

getCurrentValue

public V getCurrentValue()
                  throws IOException,
                         InterruptedException

从类复制的说明: RecordReader

Get the current value.

指定者:

getCurrentValue 在类中 RecordReader<K,V>

返回:

the object that was read

抛出:

IOException

InterruptedException

close

public void close()
           throws IOException

从类复制的说明: RecordReader

Close the record reader.

指定者:

close 在接口中 Closeable

指定者:

close 在接口中 AutoCloseable

指定者:

close 在类中 RecordReader<K,V>

抛出:

IOException

getProgress

public float getProgress()
                  throws IOException,
                         InterruptedException

return progress based on the amount of data processed so far.

指定者:

getProgress 在类中 RecordReader<K,V>

返回:

a number between 0.0 and 1.0 that is the fraction of the data read

抛出:

IOException

InterruptedException

initNextRecordReader

protected boolean initNextRecordReader()
                                throws IOException

Get the record reader for the next chunk in this CombineFileSplit.

抛出:

IOException