org.apache.hadoop.mapred.join

类 JoinRecordReader<K extends WritableComparable>

java.lang.Object

org.apache.hadoop.mapred.join.CompositeRecordReader<K,Writable,TupleWritable>

org.apache.hadoop.mapred.join.JoinRecordReader<K>

所有已实现的接口:

Comparable<ComposableRecordReader<K,?>>, Configurable, ComposableRecordReader<K,TupleWritable>, RecordReader<K,TupleWritable>

直接已知子类:

InnerJoinRecordReader, OuterJoinRecordReader

public abstract class JoinRecordReader<K extends WritableComparable>
extends CompositeRecordReader<K,Writable,TupleWritable>
implements ComposableRecordReader<K,TupleWritable>

Base class for Composite joins returning Tuples of arbitrary Writables.

嵌套类概要

嵌套类

限定符和类型	类和说明
protected class	JoinRecordReader.JoinDelegationIterator Since the JoinCollector is effecting our operation, we need only provide an iterator proxy wrapping its operation.

字段概要

从类继承的字段 org.apache.hadoop.mapred.join.CompositeRecordReader

jc, kids

构造器概要

构造器

构造器和说明
JoinRecordReader(int id, JobConf conf, int capacity, Class<? extends WritableComparator> cmpcl)

方法概要

方法

限定符和类型	方法和说明
TupleWritable	createValue() Create an object of the appropriate type to be used as a value.
protected ResetableIterator<TupleWritable>	getDelegate() Return an iterator wrapping the JoinCollector.
boolean	next(K key, TupleWritable value) Emit the next set of key, value pairs as defined by the child RecordReaders and operation associated with this composite RR.

从类继承的方法 org.apache.hadoop.mapred.join.CompositeRecordReader

accept, add, close, combine, compareTo, createInternalValue, createKey, fillJoinCollector, getComparator, getConf, getPos, getProgress, getRecordReaderQueue, hasNext, id, key, key, setConf, skip

从类继承的方法 java.lang.Object

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

从接口继承的方法 org.apache.hadoop.mapred.join.ComposableRecordReader

accept, hasNext, id, key, key, skip

从接口继承的方法 org.apache.hadoop.mapred.RecordReader

close, createKey, getPos, getProgress

从接口继承的方法 java.lang.Comparable

compareTo

构造器详细资料

JoinRecordReader

public JoinRecordReader(int id,
                JobConf conf,
                int capacity,
                Class<? extends WritableComparator> cmpcl)
                 throws IOException

抛出:

IOException

方法详细资料

next

public boolean next(K key,
           TupleWritable value)
             throws IOException

Emit the next set of key, value pairs as defined by the child RecordReaders and operation associated with this composite RR.

指定者:

next 在接口中 RecordReader<K extends WritableComparable,TupleWritable>

参数:

key - the key to read data into

value - the value to read data into

返回:

true iff a key/value was read, false if at EOF

抛出:

IOException

createValue

public TupleWritable createValue()

Create an object of the appropriate type to be used as a value.

指定者:

createValue 在接口中 RecordReader<K extends WritableComparable,TupleWritable>

返回:

a new value object.

getDelegate

protected ResetableIterator<TupleWritable> getDelegate()

Return an iterator wrapping the JoinCollector.

指定者:

getDelegate 在类中 CompositeRecordReader<K extends WritableComparable,Writable,TupleWritable>