Marshaller interface for XStream.
*
* By default, XStream does not require any further configuration, * though class aliases can be used to have more control over the behavior of XStream. * *
Due to XStream's API, it is required to set the encoding used for writing to OutputStreams.
* It defaults to UTF-8.
*
*
NOTE: XStream is an XML serialization library, not a data binding library.
* Therefore, it has limited namespace support. As such, it is rather unsuitable for
* usage within Web services.
*
* @author Peter Meijer
* @author Arjen Poutsma
* @since 3.0
* @see #setAliases
* @see #setConverters
* @see #setEncoding
*/
public class XStreamMarshaller extends AbstractMarshaller implements InitializingBean, BeanClassLoaderAware {
/**
* The default encoding used for stream access: UTF-8.
*/
public static final String DEFAULT_ENCODING = "UTF-8";
private final XStream xstream = new XStream();
private HierarchicalStreamDriver streamDriver;
private String encoding = DEFAULT_ENCODING;
private Class[] supportedClasses;
private ClassLoader classLoader;
/**
* Returns the XStream instance used by this marshaller.
*/
public XStream getXStream() {
return this.xstream;
}
/**
* Set the XStream mode.
* @see XStream#XPATH_REFERENCES
* @see XStream#ID_REFERENCES
* @see XStream#NO_REFERENCES
*/
public void setMode(int mode) {
this.getXStream().setMode(mode);
}
/**
* Set the Note that auto-detection implies that the XStream is configured while
* it is processing the XML streams, and thus introduces a potential concurrency problem.
* @see XStream#autodetectAnnotations(boolean)
*/
public void setAutodetectAnnotations(boolean autodetectAnnotations) {
this.getXStream().autodetectAnnotations(autodetectAnnotations);
}
/**
* Set the XStream hierarchical stream driver to be used with stream readers and writers.
*/
public void setStreamDriver(HierarchicalStreamDriver streamDriver) {
this.streamDriver = streamDriver;
}
/**
* Set the encoding to be used for stream access.
* @see #DEFAULT_ENCODING
*/
public void setEncoding(String encoding) {
this.encoding = encoding;
}
/**
* Set the classes supported by this marshaller.
* If this property is empty (the default), all classes are supported.
* @see #supports(Class)
*/
public void setSupportedClasses(Class[] supportedClasses) {
this.supportedClasses = supportedClasses;
}
public void setBeanClassLoader(ClassLoader classLoader) {
this.classLoader = classLoader;
}
public final void afterPropertiesSet() throws Exception {
customizeXStream(getXStream());
}
/**
* Template to allow for customizing of the given {@link XStream}.
* The default implementation is empty.
* @param xstream the {@code XStream} instance
*/
protected void customizeXStream(XStream xstream) {
}
public boolean supports(Class clazz) {
if (ObjectUtils.isEmpty(this.supportedClasses)) {
return true;
}
else {
for (Class supportedClass : this.supportedClasses) {
if (supportedClass.isAssignableFrom(clazz)) {
return true;
}
}
return false;
}
}
// Marshalling
@Override
protected void marshalDomNode(Object graph, Node node) throws XmlMappingException {
HierarchicalStreamWriter streamWriter;
if (node instanceof Document) {
streamWriter = new DomWriter((Document) node);
}
else if (node instanceof Element) {
streamWriter = new DomWriter((Element) node, node.getOwnerDocument(), new XmlFriendlyReplacer());
}
else {
throw new IllegalArgumentException("DOMResult contains neither Document nor Element");
}
marshal(graph, streamWriter);
}
@Override
protected void marshalXmlEventWriter(Object graph, XMLEventWriter eventWriter) throws XmlMappingException {
ContentHandler contentHandler = StaxUtils.createContentHandler(eventWriter);
marshalSaxHandlers(graph, contentHandler, null);
}
@Override
protected void marshalXmlStreamWriter(Object graph, XMLStreamWriter streamWriter) throws XmlMappingException {
try {
marshal(graph, new StaxWriter(new QNameMap(), streamWriter));
}
catch (XMLStreamException ex) {
throw convertXStreamException(ex, true);
}
}
@Override
protected void marshalOutputStream(Object graph, OutputStream outputStream) throws XmlMappingException, IOException {
marshalWriter(graph, new OutputStreamWriter(outputStream, this.encoding));
}
@Override
protected void marshalSaxHandlers(Object graph, ContentHandler contentHandler, LexicalHandler lexicalHandler)
throws XmlMappingException {
SaxWriter saxWriter = new SaxWriter();
saxWriter.setContentHandler(contentHandler);
marshal(graph, saxWriter);
}
@Override
protected void marshalWriter(Object graph, Writer writer) throws XmlMappingException, IOException {
if (this.streamDriver != null) {
marshal(graph, this.streamDriver.createWriter(writer));
}
else {
marshal(graph, new CompactWriter(writer));
}
}
/**
* Marshals the given graph to the given XStream HierarchicalStreamWriter.
* Converts exceptions using {@link #convertXStreamException}.
*/
private void marshal(Object graph, HierarchicalStreamWriter streamWriter) {
try {
getXStream().marshal(graph, streamWriter);
}
catch (Exception ex) {
throw convertXStreamException(ex, true);
}
finally {
try {
streamWriter.flush();
}
catch (Exception ex) {
logger.debug("Could not flush HierarchicalStreamWriter", ex);
}
}
}
// Unmarshalling
@Override
protected Object unmarshalDomNode(Node node) throws XmlMappingException {
HierarchicalStreamReader streamReader;
if (node instanceof Document) {
streamReader = new DomReader((Document) node);
}
else if (node instanceof Element) {
streamReader = new DomReader((Element) node);
}
else {
throw new IllegalArgumentException("DOMSource contains neither Document nor Element");
}
return unmarshal(streamReader);
}
@Override
protected Object unmarshalXmlEventReader(XMLEventReader eventReader) throws XmlMappingException {
try {
XMLStreamReader streamReader = StaxUtils.createEventStreamReader(eventReader);
return unmarshalXmlStreamReader(streamReader);
}
catch (XMLStreamException ex) {
throw convertXStreamException(ex, false);
}
}
@Override
protected Object unmarshalXmlStreamReader(XMLStreamReader streamReader) throws XmlMappingException {
return unmarshal(new StaxReader(new QNameMap(), streamReader));
}
@Override
protected Object unmarshalInputStream(InputStream inputStream) throws XmlMappingException, IOException {
return unmarshalReader(new InputStreamReader(inputStream, this.encoding));
}
@Override
protected Object unmarshalReader(Reader reader) throws XmlMappingException, IOException {
if (streamDriver != null) {
return unmarshal(streamDriver.createReader(reader));
}
else {
return unmarshal(new XppReader(reader));
}
}
@Override
protected Object unmarshalSaxReader(XMLReader xmlReader, InputSource inputSource)
throws XmlMappingException, IOException {
throw new UnsupportedOperationException(
"XStreamMarshaller does not support unmarshalling using SAX XMLReaders");
}
private Object unmarshal(HierarchicalStreamReader streamReader) {
try {
return this.getXStream().unmarshal(streamReader);
}
catch (Exception ex) {
throw convertXStreamException(ex, false);
}
}
/**
* Convert the given XStream exception to an appropriate exception from the
* A boolean flag is used to indicate whether this exception occurs during marshalling or
* unmarshalling, since XStream itself does not make this distinction in its exception hierarchy.
* @param ex XStream exception that occured
* @param marshalling indicates whether the exception occurs during marshalling (Converters or SingleValueConverters to be registered
* with the XStream instance.
* @see Converter
* @see SingleValueConverter
*/
public void setConverters(ConverterMatcher[] converters) {
for (int i = 0; i < converters.length; i++) {
if (converters[i] instanceof Converter) {
this.getXStream().registerConverter((Converter) converters[i], i);
}
else if (converters[i] instanceof SingleValueConverter) {
this.getXStream().registerConverter((SingleValueConverter) converters[i], i);
}
else {
throw new IllegalArgumentException("Invalid ConverterMatcher [" + converters[i] + "]");
}
}
}
/**
* Sets an alias/type map, consisting of string aliases mapped to classes. Keys are aliases; values are either
* {@code Class} instances, or String class names.
* @see XStream#alias(String, Class)
*/
public void setAliases(MapClass instances
* mapped to comma separated collection field names.
*@see XStream#addImplicitCollection(Class, String)
*/
public void setImplicitCollections(MapClass instances
* mapped to comma separated field names.
* @see XStream#omitField(Class, String)
*/
public void setOmittedFields(Maporg.springframework.oxm hierarchy.
* true),
* or unmarshalling (false)
* @return the corresponding XmlMappingException
*/
protected XmlMappingException convertXStreamException(Exception ex, boolean marshalling) {
if (ex instanceof StreamException || ex instanceof CannotResolveClassException ||
ex instanceof ConversionException) {
if (marshalling) {
return new MarshallingFailureException("XStream marshalling exception", ex);
}
else {
return new UnmarshallingFailureException("XStream unmarshalling exception", ex);
}
}
else {
// fallback
return new UncategorizedMappingException("Unknown XStream exception", ex);
}
}
}