org.springframework.batch.item.xml

Class StaxEventItemWriter<T>

java.lang.Object

org.springframework.batch.item.ItemStreamSupport

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

org.springframework.batch.item.xml.StaxEventItemWriter<T>

All Implemented Interfaces:

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

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

An implementation of ItemWriter which uses StAX and Marshaller for serializing object to XML. This item writer also provides restart, statistics and transaction features by implementing corresponding interfaces. The implementation is not thread-safe.

Author:

Peter Zozom, Robert Kasanicky, Michael Minella

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	DEFAULT_ENCODING
static java.lang.String	DEFAULT_ROOT_TAG_NAME
static java.lang.String	DEFAULT_XML_VERSION

Constructor Summary

Constructors

Constructor and Description
StaxEventItemWriter()

Method Summary

Modifier and Type	Method and Description
void	afterPropertiesSet()
void	close() Flush and close the output source.
protected javax.xml.transform.Result	createStaxResult() Subclasses can override to customize the STAX result.
protected javax.xml.stream.XMLEventFactory	createXmlEventFactory() Subclasses can override to customize the event factory.
protected javax.xml.stream.XMLEventWriter	createXmlEventWriter(javax.xml.stream.XMLOutputFactory outputFactory, java.io.Writer writer) Subclasses can override to customize the writer.
protected javax.xml.stream.XMLOutputFactory	createXmlOutputFactory() Subclasses can override to customize the factory.
protected void	endDocument(javax.xml.stream.XMLEventWriter writer) Writes the EndDocument tag manually.
java.lang.String	getEncoding() Get used encoding.
java.util.Map<java.lang.String,java.lang.String>	getRootElementAttributes() Get attributes of the root element.
java.lang.String	getRootTagName() Get the tag name of the root element.
java.lang.String	getRootTagNamespace() Get the namespace of the root element.
java.lang.String	getRootTagNamespacePrefix() Get the namespace prefix of the root element.
java.lang.String	getVersion() Get XML version.
protected void	initNamespaceContext(javax.xml.stream.XMLEventWriter writer) Inits the namespace context of the XMLEventWriter: rootTagNamespacePrefix for rootTagName any other xmlns namespace prefix declarations in the root element attributes
void	open(ExecutionContext executionContext) Open the output source
void	setEncoding(java.lang.String encoding) Set encoding to be used for output file.
void	setFooterCallback(StaxWriterCallback footerCallback) footerCallback is called after writing all items but before closing the file.
void	setForceSync(boolean forceSync) Flag to indicate that changes should be force-synced to disk on flush.
void	setHeaderCallback(StaxWriterCallback headerCallback) headerCallback is called before writing any items.
void	setMarshaller(org.springframework.oxm.Marshaller marshaller) Set Object to XML marshaller.
void	setOverwriteOutput(boolean overwriteOutput) Set "overwrite" flag for the output file.
void	setResource(org.springframework.core.io.Resource resource) Set output file.
void	setRootElementAttributes(java.util.Map<java.lang.String,java.lang.String> rootElementAttributes) Set the root element attributes to be written.
void	setRootTagName(java.lang.String rootTagName) Set the tag name of the root element.
void	setSaveState(boolean saveState)
void	setShouldDeleteIfEmpty(boolean shouldDeleteIfEmpty) Flag to indicate that the target file should be deleted if no items have been written (other than header and footer) on close.
void	setTransactional(boolean transactional) Flag to indicate that writes should be deferred to the end of a transaction if present.
void	setVersion(java.lang.String version) Set XML version to be used for output XML.
protected void	startDocument(javax.xml.stream.XMLEventWriter writer) Writes simple XML header containing: xml declaration - defines encoding and XML version opening tag of the root element and its attributes If this is not sufficient for you, simply override this method.
void	update(ExecutionContext executionContext) Get the restart data.
void	write(java.util.List<? extends T> items) Write the value objects and flush them to the file.

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

Field Detail

DEFAULT_ENCODING

public static final java.lang.String DEFAULT_ENCODING

See Also:

Constant Field Values

DEFAULT_XML_VERSION

public static final java.lang.String DEFAULT_XML_VERSION

See Also:

Constant Field Values

DEFAULT_ROOT_TAG_NAME

public static final java.lang.String DEFAULT_ROOT_TAG_NAME

See Also:

Constant Field Values

Constructor Detail

StaxEventItemWriter

public StaxEventItemWriter()

Method Detail

setResource

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

Set output file.

Specified by:

setResource in interface ResourceAwareItemWriterItemStream<T>

Parameters:

resource - the output file

setMarshaller

public void setMarshaller(org.springframework.oxm.Marshaller marshaller)

Set Object to XML marshaller.

Parameters:

marshaller - the Object to XML marshaller

setHeaderCallback

public void setHeaderCallback(StaxWriterCallback headerCallback)

headerCallback is called before writing any items.

Parameters:

headerCallback - the StaxWriterCallback to be called prior to writing items.

setFooterCallback

public void setFooterCallback(StaxWriterCallback footerCallback)

footerCallback is called after writing all items but before closing the file.

Parameters:

footerCallback - the StaxWriterCallback to be called after writing items.

setTransactional

public void setTransactional(boolean transactional)

Flag to indicate that writes should be deferred to the end of a transaction if present. Defaults to true.

Parameters:

transactional - the flag to set

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

setShouldDeleteIfEmpty

public void setShouldDeleteIfEmpty(boolean shouldDeleteIfEmpty)

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

Parameters:

shouldDeleteIfEmpty - the flag value to set

getEncoding

public java.lang.String getEncoding()

Get used encoding.

Returns:

the encoding used

setEncoding

public void setEncoding(java.lang.String encoding)

Set encoding to be used for output file.

Parameters:

encoding - the encoding to be used

getVersion

public java.lang.String getVersion()

Get XML version.

Returns:

the XML version used

setVersion

public void setVersion(java.lang.String version)

Set XML version to be used for output XML.

Parameters:

version - the XML version to be used

getRootTagName

public java.lang.String getRootTagName()

Get the tag name of the root element.

Returns:

the root element tag name

setRootTagName

public void setRootTagName(java.lang.String rootTagName)

Set the tag name of the root element. If not set, default name is used ("root"). Namespace URI and prefix can also be set optionally using the notation:

 {uri}prefix:root
 

The prefix is optional (defaults to empty), but if it is specified then the uri must be provided. In addition you might want to declare other namespaces using the root attributes.

Parameters:

rootTagName - the tag name to be used for the root element

getRootTagNamespacePrefix

public java.lang.String getRootTagNamespacePrefix()

Get the namespace prefix of the root element. Empty by default.

Returns:

the rootTagNamespacePrefix

getRootTagNamespace

public java.lang.String getRootTagNamespace()

Get the namespace of the root element.

Returns:

the rootTagNamespace

getRootElementAttributes

public java.util.Map<java.lang.String,java.lang.String> getRootElementAttributes()

Get attributes of the root element.

Returns:

attributes of the root element

setRootElementAttributes

public void setRootElementAttributes(java.util.Map<java.lang.String,java.lang.String> rootElementAttributes)

Set the root element attributes to be written. If any of the key names begin with "xmlns:" then they are treated as namespace declarations.

Parameters:

rootElementAttributes - attributes of the root element

setOverwriteOutput

public void setOverwriteOutput(boolean overwriteOutput)

Set "overwrite" flag for the output file. Flag is ignored when output file processing is restarted.

Parameters:

overwriteOutput - If set to true, output file will be overwritten (this flag is ignored when processing is restart).

setSaveState

public void setSaveState(boolean saveState)

afterPropertiesSet

public void afterPropertiesSet()
                        throws java.lang.Exception

Specified by:

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

Throws:

java.lang.Exception - thrown if error occurs

See Also:

InitializingBean.afterPropertiesSet()

open

public void open(ExecutionContext executionContext)

Open the output source

Specified by:

open in interface ItemStream

Overrides:

open in class ItemStreamSupport

Parameters:

executionContext - the batch context.

See Also:

ItemStream.open(ExecutionContext)

createXmlEventWriter

protected javax.xml.stream.XMLEventWriter createXmlEventWriter(javax.xml.stream.XMLOutputFactory outputFactory,
                                                               java.io.Writer writer)
                                                        throws javax.xml.stream.XMLStreamException

Subclasses can override to customize the writer.

Parameters:

outputFactory - the factory to be used to create an XMLEventWriter.

writer - the Writer to be used by the XMLEventWriter for writing to character streams.

Returns:

an xml writer

Throws:

javax.xml.stream.XMLStreamException - thrown if error occured creating XMLEventWriter.

createXmlOutputFactory

protected javax.xml.stream.XMLOutputFactory createXmlOutputFactory()
                                                            throws javax.xml.stream.FactoryConfigurationError

Subclasses can override to customize the factory.

Returns:

a factory for the xml output

Throws:

javax.xml.stream.FactoryConfigurationError - throw if an instance of this factory cannot be loaded.

createXmlEventFactory

protected javax.xml.stream.XMLEventFactory createXmlEventFactory()
                                                          throws javax.xml.stream.FactoryConfigurationError

Subclasses can override to customize the event factory.

Returns:

a factory for the xml events

Throws:

javax.xml.stream.FactoryConfigurationError - thrown if an instance of this factory cannot be loaded.

createStaxResult

protected javax.xml.transform.Result createStaxResult()

Subclasses can override to customize the STAX result.

Returns:

a result for writing to

initNamespaceContext

protected void initNamespaceContext(javax.xml.stream.XMLEventWriter writer)
                             throws javax.xml.stream.XMLStreamException

Inits the namespace context of the XMLEventWriter:

• rootTagNamespacePrefix for rootTagName
• any other xmlns namespace prefix declarations in the root element attributes

Parameters:

writer - XML event writer

Throws:

javax.xml.stream.XMLStreamException - thrown if error occurs while setting the prefix or default name space.

startDocument

protected void startDocument(javax.xml.stream.XMLEventWriter writer)
                      throws javax.xml.stream.XMLStreamException

Writes simple XML header containing:

• xml declaration - defines encoding and XML version
• opening tag of the root element and its attributes

If this is not sufficient for you, simply override this method. Encoding, version and root tag name can be retrieved with corresponding getters.

Parameters:

writer - XML event writer

Throws:

javax.xml.stream.XMLStreamException - thrown if error occurs.

endDocument

protected void endDocument(javax.xml.stream.XMLEventWriter writer)
                    throws javax.xml.stream.XMLStreamException

Writes the EndDocument tag manually.

Parameters:

writer - XML event writer

Throws:

javax.xml.stream.XMLStreamException - thrown if error occurs.

close

public void close()

Flush and close the output source.

Specified by:

close in interface ItemStream

Overrides:

close in class ItemStreamSupport

See Also:

ItemStream.close()

write

public void write(java.util.List<? extends T> items)
           throws org.springframework.oxm.XmlMappingException,
                  java.io.IOException

Write the value objects and flush them to the file.

Specified by:

write in interface ItemWriter<T>

Parameters:

items - the value object

Throws:

java.io.IOException - thrown if general error occurs.

org.springframework.oxm.XmlMappingException - thrown if error occurs during XML Mapping.

update

public void update(ExecutionContext executionContext)

Get the restart data.

Specified by:

update in interface ItemStream

Overrides:

update in class ItemStreamSupport

Parameters:

executionContext - the batch context.

See Also:

ItemStream.update(ExecutionContext)