org.springframework.batch.item.file

Class FlatFileItemWriter<T>

java.lang.Object

org.springframework.batch.item.util.ExecutionContextUserSupport

org.springframework.batch.item.file.FlatFileItemWriter<T>

All Implemented Interfaces:

ResourceAwareItemWriterItemStream<T>, ItemStream, ItemWriter<T>, org.springframework.beans.factory.InitializingBean

public class FlatFileItemWriter<T>
extends ExecutionContextUserSupport
implements ResourceAwareItemWriterItemStream<T>, org.springframework.beans.factory.InitializingBean

This class is an item writer that writes data to a file or stream. The writer also provides restart. The location of the output file is defined by a Resource and must represent a writable file.
Uses buffered writer to improve performance.
The implementation is *not* thread-safe.

Author:

Waseem Malik, Tomas Slanina, Robert Kasanicky, Dave Syer

Field Summary

Fields

Modifier and Type	Field and Description
protected static org.apache.commons.logging.Log	logger

Constructor Summary

Constructors

Constructor and Description
FlatFileItemWriter()

Method Summary

Modifier and Type	Method and Description
void	afterPropertiesSet() Assert that mandatory properties (lineAggregator) are set.
void	close() If any resources are needed for the stream to operate they need to be destroyed here.
void	open(ExecutionContext executionContext) Initialize the reader.
void	setAppendAllowed(boolean append) Flag to indicate that the target file should be appended if it already exists.
void	setEncoding(String newEncoding) Sets encoding for output template.
void	setFooterCallback(FlatFileFooterCallback footerCallback) footerCallback will be called after writing the last item to file, but before the file is closed.
void	setForceSync(boolean forceSync) Flag to indicate that changes should be force-synced to disk on flush.
void	setHeaderCallback(FlatFileHeaderCallback headerCallback) headerCallback will be called before writing the first item to file.
void	setLineAggregator(LineAggregator<T> lineAggregator) Public setter for the LineAggregator.
void	setLineSeparator(String lineSeparator) Public setter for the line separator.
void	setResource(org.springframework.core.io.Resource resource) Setter for resource.
void	setSaveState(boolean saveState) Set the flag indicating whether or not state should be saved in the provided ExecutionContext during the ItemStream call to update.
void	setShouldDeleteIfEmpty(boolean shouldDeleteIfEmpty) Flag to indicate that the target file should be deleted if no lines have been written (other than header and footer) on close.
void	setShouldDeleteIfExists(boolean shouldDeleteIfExists) Flag to indicate that the target file should be deleted if it already exists, otherwise it will be created.
void	setTransactional(boolean transactional) Flag to indicate that writing to the buffer should be delayed if a transaction is active.
void	update(ExecutionContext executionContext) Indicates that the execution context provided during open is about to be saved.
void	write(List<? extends T> items) Writes out a string followed by a "new line", where the format of the new line separator is determined by the underlying operating system.

Methods inherited from class org.springframework.batch.item.util.ExecutionContextUserSupport

getKey, getName, setName

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected static final org.apache.commons.logging.Log logger

Constructor Detail

FlatFileItemWriter

public FlatFileItemWriter()

Method Detail

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Assert that mandatory properties (lineAggregator) are set.

Specified by:

afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean

Throws:

Exception

See Also:

InitializingBean.afterPropertiesSet()

setForceSync

public void setForceSync(boolean forceSync)

Flag to indicate that changes should be force-synced to disk on flush. Defaults to false, which means that even with a local disk changes could be lost if the OS crashes in between a write and a cache flush. Setting to true may result in slower performance for usage patterns involving many frequent writes.

Parameters:

forceSync - the flag value to set

setLineSeparator

public void setLineSeparator(String lineSeparator)

Public setter for the line separator. Defaults to the System property line.separator.

Parameters:

lineSeparator - the line separator to set

setLineAggregator

public void setLineAggregator(LineAggregator<T> lineAggregator)

Public setter for the LineAggregator. This will be used to translate the item into a line for output.

Parameters:

lineAggregator - the LineAggregator to set

setResource

public void setResource(org.springframework.core.io.Resource resource)

Setter for resource. Represents a file that can be written.

Specified by:

setResource in interface ResourceAwareItemWriterItemStream<T>

Parameters:

resource -

setEncoding

public void setEncoding(String newEncoding)

Sets encoding for output template.

setShouldDeleteIfExists

public void setShouldDeleteIfExists(boolean shouldDeleteIfExists)

Flag to indicate that the target file should be deleted if it already exists, otherwise it will be created. Defaults to true, so no appending except on restart. If set to false and appendAllowed is also false then there will be an exception when the stream is opened to prevent existing data being potentially corrupted.

Parameters:

shouldDeleteIfExists - the flag value to set

setAppendAllowed

public void setAppendAllowed(boolean append)

Flag to indicate that the target file should be appended if it already exists. If this flag is set then the flag shouldDeleteIfExists is automatically set to false, so that flag should not be set explicitly. Defaults value is false.

Parameters:

append - the flag value to set

setShouldDeleteIfEmpty

public void setShouldDeleteIfEmpty(boolean shouldDeleteIfEmpty)

Flag to indicate that the target file should be deleted if no lines have been written (other than header and footer) on close. Defaults to false.

Parameters:

shouldDeleteIfEmpty - the flag value to set

setSaveState

public void setSaveState(boolean saveState)

Set the flag indicating whether or not state should be saved in the provided ExecutionContext during the ItemStream call to update. Setting this to false means that it will always start at the beginning on a restart.

Parameters:

saveState -

setHeaderCallback

public void setHeaderCallback(FlatFileHeaderCallback headerCallback)

headerCallback will be called before writing the first item to file. Newline will be automatically appended after the header is written.

setFooterCallback

public void setFooterCallback(FlatFileFooterCallback footerCallback)

footerCallback will be called after writing the last item to file, but before the file is closed.

setTransactional

public void setTransactional(boolean transactional)

Flag to indicate that writing to the buffer should be delayed if a transaction is active. Defaults to true.

write

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

Writes out a string followed by a "new line", where the format of the new line separator is determined by the underlying operating system. If the input is not a String and a converter is available the converter will be applied and then this method recursively called with the result. If the input is an array or collection each value will be written to a separate line (recursively calling this method for each value). If no converter is supplied the input object's toString method will be used.

Specified by:

write in interface ItemWriter<T>

Parameters:

items - list of items to be written to output stream

Throws:

Exception - if the transformer or file output fail, WriterNotOpenException if the writer has not been initialized.

close

public void close()

Description copied from interface: ItemStream

If any resources are needed for the stream to operate they need to be destroyed here. Once this method has been called all other methods (except open) may throw an exception.

Specified by:

close in interface ItemStream

See Also:

ItemStream.close()

open

public void open(ExecutionContext executionContext)
          throws ItemStreamException

Initialize the reader. This method may be called multiple times before close is called.

Specified by:

open in interface ItemStream

Throws:

ItemStreamException

See Also:

ItemStream.open(ExecutionContext)

update

public void update(ExecutionContext executionContext)

Description copied from interface: ItemStream

Indicates that the execution context provided during open is about to be saved. If any state is remaining, but has not been put in the context, it should be added here.

Specified by:

update in interface ItemStream

Parameters:

executionContext - to be updated

See Also:

ItemStream.update(ExecutionContext)