org.springframework.batch.item.support

Class AbstractFileItemWriter<T>

java.lang.Object

org.springframework.batch.item.ItemStreamSupport

org.springframework.batch.item.support.AbstractItemStreamItemWriter<T>

org.springframework.batch.item.support.AbstractFileItemWriter<T>

All Implemented Interfaces:

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

Direct Known Subclasses:

FlatFileItemWriter, JsonFileItemWriter

public abstract class AbstractFileItemWriter<T>
extends AbstractItemStreamItemWriter<T>
implements ResourceAwareItemWriterItemStream<T>, org.springframework.beans.factory.InitializingBean

Base class for item writers that write data to a file or stream. This class provides common features like restart, force sync, append etc. The location of the output file is defined by a Resource which must represent a writable file.
Uses buffered writer to improve performance.
The implementation is not thread-safe.

Since:

4.1

Author:

Waseem Malik, Tomas Slanina, Robert Kasanicky, Dave Syer, Michael Minella, Mahmoud Ben Hassine, Remi Kaeffer

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	AbstractFileItemWriter.OutputState Encapsulates the runtime state of the writer.

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	append
static java.lang.String	DEFAULT_CHARSET
static java.lang.String	DEFAULT_LINE_SEPARATOR
static boolean	DEFAULT_TRANSACTIONAL
protected java.lang.String	lineSeparator
protected static org.apache.commons.logging.Log	logger
protected boolean	shouldDeleteIfExists
protected AbstractFileItemWriter.OutputState	state

Constructor Summary

Constructors

Constructor and Description
AbstractFileItemWriter()

Method Summary

Modifier and Type	Method and Description
void	close() No-op.
protected abstract java.lang.String	doWrite(java.util.List<? extends T> items) Write out a string of items followed by a "new line", where the format of the new line separator is determined by the underlying operating system.
protected AbstractFileItemWriter.OutputState	getOutputState()
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(java.lang.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	setLineSeparator(java.lang.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) Return empty ExecutionContext.
void	write(java.util.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.ItemStreamSupport

getExecutionContextKey, setExecutionContextName, setName

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.beans.factory.InitializingBean

afterPropertiesSet

Field Detail

DEFAULT_TRANSACTIONAL

public static final boolean DEFAULT_TRANSACTIONAL

See Also:

Constant Field Values

logger

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

DEFAULT_LINE_SEPARATOR

public static final java.lang.String DEFAULT_LINE_SEPARATOR

DEFAULT_CHARSET

public static final java.lang.String DEFAULT_CHARSET

See Also:

Constant Field Values

state

protected AbstractFileItemWriter.OutputState state

shouldDeleteIfExists

protected boolean shouldDeleteIfExists

lineSeparator

protected java.lang.String lineSeparator

append

protected boolean append

Constructor Detail

AbstractFileItemWriter

public AbstractFileItemWriter()

Method Detail

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(java.lang.String lineSeparator)

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

Parameters:

lineSeparator - the line separator 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 - the resource to be written to

setEncoding

public void setEncoding(java.lang.String newEncoding)

Sets encoding for output template.

Parameters:

newEncoding - String containing the encoding to be used for the writer.

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 - if true, state will be persisted

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.

Parameters:

headerCallback - FlatFileHeaderCallback to generate the header

setFooterCallback

public void setFooterCallback(FlatFileFooterCallback footerCallback)

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

Parameters:

footerCallback - FlatFileFooterCallback to generate the footer

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.

Parameters:

transactional - true if writing to buffer should be delayed.

write

public void write(java.util.List<? extends T> items)
           throws java.lang.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.

Specified by:

write in interface ItemWriter<T>

Parameters:

items - list of items to be written to output stream

Throws:

java.lang.Exception - if an error occurs while writing items to the output stream

doWrite

protected abstract java.lang.String doWrite(java.util.List<? extends T> items)

Write out a string of items followed by a "new line", where the format of the new line separator is determined by the underlying operating system.

Parameters:

items - to be written

Returns:

written lines

close

public void close()

Description copied from class: ItemStreamSupport

No-op.

Specified by:

close in interface ItemStream

Overrides:

close in class ItemStreamSupport

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

Overrides:

open in class ItemStreamSupport

Parameters:

executionContext - current step's ExecutionContext. Will be the executionContext from the last run of the step on a restart.

Throws:

ItemStreamException

See Also:

ItemStream.open(ExecutionContext)

update

public void update(ExecutionContext executionContext)

Description copied from class: ItemStreamSupport

Return empty ExecutionContext.

Specified by:

update in interface ItemStream

Overrides:

update in class ItemStreamSupport

Parameters:

executionContext - to be updated

See Also:

ItemStream.update(ExecutionContext)

getOutputState

protected AbstractFileItemWriter.OutputState getOutputState()