org.springframework.data.hadoop.fs
Class HdfsItemWriter<T>

java.lang.Object
  org.springframework.data.hadoop.fs.HdfsItemWriter<T>

All Implemented Interfaces:

ItemStream, ItemStreamWriter<T>, ItemWriter<T>

public class HdfsItemWriter<T>
extends Object
implements ItemStreamWriter<T>

An ItemWriter implementation used to write the incoming items to HDFS. Due to the HDFS limitation that files cannot be deleted or modified, the ability to roll back a file to a previously known state is not possible. This prevents the ability to restart using this ItemWriter.
This ItemWriter is not thread-safe.

Author:

Michael Minella

Constructor Summary

HdfsItemWriter(FileSystem fileSystem, Serializer<T> itemSerializer, String fileName)
Constructor

Method Summary

void	close()
protected void	doWrite(List<? extends T> items) Performs the actual write to the store via the template.
void	open(ExecutionContext executionContext)
void	update(ExecutionContext executionContext)
void	write(List<? extends T> items)

Methods inherited from class java.lang.Object

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

Constructor Detail

HdfsItemWriter

public HdfsItemWriter(FileSystem fileSystem,
                      Serializer<T> itemSerializer,
                      String fileName)

Constructor

Parameters:

fileSystem - - HDFS FileSystem reference

itemSerializer - - Strategy for serializing items

fileName - - Name of the file to be written to

Method Detail

doWrite

protected void doWrite(List<? extends T> items)

Performs the actual write to the store via the template. This can be overridden by a subclass if necessary.

Parameters:

items - the list of items to be persisted.

open

public void open(ExecutionContext executionContext)
          throws ItemStreamException

Specified by:

open in interface ItemStream

Throws:

ItemStreamException

update

public void update(ExecutionContext executionContext)
            throws ItemStreamException

Specified by:

update in interface ItemStream

Throws:

ItemStreamException

write

public void write(List<? extends T> items)
           throws Exception

Specified by:

write in interface ItemWriter<T>

Throws:

Exception

close

public void close()

Specified by:

close in interface ItemStream