Option to allow marshaller skip xml declarations [SWS-181]

[gregturn]

Peter Zozom opened SWS-181 and commented

For Spring Batch's Xml IO sources will be helpful to have method setXmlDecl(boolean) in org.springframework.oxm.Marshaller interface, which will configure marshaller to turn on/off writing StartDocument event and EndDocument event for each call of marshall() method.

See new XML I/O sources attached as SVN patch in issue:
http://opensource.atlassian.com/projects/spring/browse/BATCH-116

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Issue Links:

• BATCH-116 Create XML input/output source which will work directly with StAX parser

[gregturn]

Martin Bosak commented

The same functionality needs to be done for Jibx Marshaller.

Here's how I patched the JibxMarshaller.java class to do it:

protected void marshalOutputStream(Object graph, OutputStream outputStream)
        throws XmlMappingException, IOException {
    try {
        IMarshallingContext marshallingContext = createMarshallingContext();
    marshallingContext.setOutput(outputStream, encoding);
        marshallingContext.marshalDocument(graph);
    }
    catch (JiBXException ex) {
        throw convertJibxException(ex, true);
    }
}

protected void marshalWriter(Object graph, Writer writer) throws XmlMappingException, IOException {
    try {
        IMarshallingContext marshallingContext = createMarshallingContext();
    marshallingContext.setOutput(writer);
        marshallingContext.marshalDocument(graph);
    }
    catch (JiBXException ex) {
        throw convertJibxException(ex, true);
    }
}

[gregturn]

Arjen Poutsma commented

The reason I cannot fix the Marshaller like you suggested in http://opensource.atlassian.com/projects/spring/browse/SWS-181 is this: the Marshaller is very generic: it can marshal to DOM documents, SAX ContentHandlers, file streams, and Stax XMLEventReader/XMLEventWriters. Filtering out the Start/EndDocument events would only work for Stax, and perhaps SAX. Adding a property to this effect would very confusing, since it does not work in other cases (marshalling to DOM). This would break the principle of least astonishment.

But there is a way you can filter out these events, by creating a delegating XMLStreamWriter, which ignores start and end document events, but passes through everything else:

import javax.xml.stream.*;

public class NoStartEndDocumentStreamWriter implements XMLStreamWriter {

private XMLStreamWriter delegate;

public NoStartEndDocumentStreamWriter(XMLStreamWriter delegate) {
this.delegate = delegate;
}

void writeStartDocument() throws XMLStreamException {
// ignore
}

void writeStartDocument(String version) throws XMLStreamException {
// ignore
}

void writeStartDocument(String encoding,String version) throws XMLStreamException {
// ignore
}

void writeEndDocument() throws XMLStreamException {
// ignore
}

void close() throws XMLStreamException {
// ignore
}

void writeStartElement(String localName) throws XMLStreamException {
delegate.writeStartElement(localName);
}

void writeStartElement(String namespaceURI,
String localName)
throws XMLStreamException {
delegate.writeStartElement(namespaceURI, localName);
}

// et cetera, delegating all the other methods of the stream writer to the delegate field

}

Then you can create a XMLStreamReader that uses this filter:

streamWriter = outputFactory.createXMLStreamWriter(os, encoding);
streamWriter = new NoStartEndDocumentStreamWriter(streamWriter);

[gregturn]

Arjen Poutsma commented

Closing 1.0.1 issues.