javax.xml.bind: public interface: Marshaller

javax.xml.bind
public interface: Marshaller [javadoc | source]

All Known Implementing Classes:
AbstractMarshallerImpl

The Marshaller class is responsible for governing the process of serializing Java content trees back into XML data. It provides the basic marshalling methods:

Assume the following setup code for all following code fragments:

      JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
      Unmarshaller u = jc.createUnmarshaller();
      Object element = u.unmarshal( new File( "foo.xml" ) );
      Marshaller m = jc.createMarshaller();

Marshalling to a File:

      OutputStream os = new FileOutputStream( "nosferatu.xml" );
      m.marshal( element, os );

Marshalling to a SAX ContentHandler:

      // assume MyContentHandler instanceof ContentHandler
      m.marshal( element, new MyContentHandler() );

Marshalling to a DOM Node:

      DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
      dbf.setNamespaceAware(true);
      DocumentBuilder db = dbf.newDocumentBuilder();
      Document doc = db.newDocument();

      m.marshal( element, doc );

Marshalling to a java.io.OutputStream:

      m.marshal( element, System.out );

Marshalling to a java.io.Writer:

      m.marshal( element, new PrintWriter( System.out ) );

Marshalling to a javax.xml.transform.SAXResult:

      // assume MyContentHandler instanceof ContentHandler
      SAXResult result = new SAXResult( new MyContentHandler() );

      m.marshal( element, result );

Marshalling to a javax.xml.transform.DOMResult:

      DOMResult result = new DOMResult();

      m.marshal( element, result );

Marshalling to a javax.xml.transform.StreamResult:

      StreamResult result = new StreamResult( System.out );

      m.marshal( element, result );

Marshalling to a javax.xml.stream.XMLStreamWriter:

      XMLStreamWriter xmlStreamWriter =
          XMLOutputFactory.newInstance().createXMLStreamWriter( ... );

      m.marshal( element, xmlStreamWriter );

Marshalling to a javax.xml.stream.XMLEventWriter:

      XMLEventWriter xmlEventWriter =
          XMLOutputFactory.newInstance().createXMLEventWriter( ... );

      m.marshal( element, xmlEventWriter );

Marshalling content tree rooted by a JAXB element

The first parameter of the overloaded Marshaller.marshal(java.lang.Object, ...) methods must be a JAXB element as computed by JAXBIntrospector#isElement(java.lang.Object) ; otherwise, a Marshaller.marshal method must throw a MarshalException . There exist two mechanisms to enable marshalling an instance that is not a JAXB element. One method is to wrap the instance as a value of a JAXBElement , and pass the wrapper element as the first parameter to a Marshaller.marshal method. For java to schema binding, it is also possible to simply annotate the instance's class with @XmlRootElement .

Encoding

By default, the Marshaller will use UTF-8 encoding when generating XML data to a java.io.OutputStream, or a java.io.Writer. Use the setProperty API to change the output encoding used during these marshal operations. Client applications are expected to supply a valid character encoding name as defined in the W3C XML 1.0 Recommendation and supported by your Java Platform.

Validation and Well-Formedness

Client applications are not required to validate the Java content tree prior to calling any of the marshal API's. Furthermore, there is no requirement that the Java content tree be valid with respect to its original schema in order to marshal it back into XML data. Different JAXB Providers will support marshalling invalid Java content trees at varying levels, however all JAXB Providers must be able to marshal a valid content tree back to XML data. A JAXB Provider must throw a MarshalException when it is unable to complete the marshal operation due to invalid content. Some JAXB Providers will fully allow marshalling invalid content, others will fail on the first validation error.
Even when schema validation is not explictly enabled for the marshal operation, it is possible that certain types of validation events will be detected during the operation. Validation events will be reported to the registered event handler. If the client application has not registered an event handler prior to invoking one of the marshal API's, then events will be delivered to a default event handler which will terminate the marshal operation after encountering the first error or fatal error. Note that for JAXB 2.0 and later versions, javax.xml.bind.helpers.DefaultValidationEventHandler is no longer used.

Supported Properties

All JAXB Providers are required to support the following set of properties. Some providers may support additional properties.

jaxb.encoding - value must be a java.lang.String
The output encoding to use when marshalling the XML data. The Marshaller will use "UTF-8" by default if this property is not specified.

jaxb.formatted.output - value must be a java.lang.Boolean
This property controls whether or not the Marshaller will format the resulting XML data with line breaks and indentation. A true value for this property indicates human readable indented xml data, while a false value indicates unformatted xml data. The Marshaller will default to false (unformatted) if this property is not specified.

jaxb.schemaLocation - value must be a java.lang.String
This property allows the client application to specify an xsi:schemaLocation attribute in the generated XML data. The format of the schemaLocation attribute value is discussed in an easy to understand, non-normative form in Section 5.6 of the W3C XML Schema Part 0: Primer and specified in Section 2.6 of the W3C XML Schema Part 1: Structures.

jaxb.noNamespaceSchemaLocation - value must be a java.lang.String
This property allows the client application to specify an xsi:noNamespaceSchemaLocation attribute in the generated XML data. The format of the schemaLocation attribute value is discussed in an easy to understand, non-normative form in Section 5.6 of the W3C XML Schema Part 0: Primer and specified in Section 2.6 of the W3C XML Schema Part 1: Structures.

jaxb.fragment - value must be a java.lang.Boolean
This property determines whether or not document level events will be generated by the Marshaller. If the property is not specified, the default is false. This property has different implications depending on which marshal api you are using - when this property is set to true:

marshal(Object,ContentHandler) - the Marshaller won't invoke org.xml.sax.ContentHandler#startDocument() and org.xml.sax.ContentHandler#endDocument() .

marshal(Object,Node) - the property has no effect on this API.

marshal(Object,OutputStream) - the Marshaller won't generate an xml declaration.

marshal(Object,Writer) - the Marshaller won't generate an xml declaration.

marshal(Object,Result) - depends on the kind of Result object, see semantics for Node, ContentHandler, and Stream APIs

marshal(Object,XMLEventWriter) - the Marshaller will not generate javax.xml.stream.events.XMLEvent#START_DOCUMENT and javax.xml.stream.events.XMLEvent#END_DOCUMENT events.

marshal(Object,XMLStreamWriter) - the Marshaller will not generate javax.xml.stream.events.XMLEvent#START_DOCUMENT and javax.xml.stream.events.XMLEvent#END_DOCUMENT events.

Marshal Event Callbacks

"The Marshaller provides two styles of callback mechanisms that allow application specific processing during key points in the unmarshalling process. In 'class defined' event callbacks, application specific code placed in JAXB mapped classes is triggered during marshalling. 'External listeners' allow for centralized processing of marshal events in one callback method rather than by type event callbacks.
Class defined event callback methods allow any JAXB mapped class to specify its own specific callback methods by defining methods with the following method signatures:
  // Invoked by Marshaller after it has created an instance of this object.
  boolean beforeMarshal(Marshaller);

  // Invoked by Marshaller after it has marshalled all properties of this object.
  void afterMmarshal(Marshaller);
The class defined event callback methods should be used when the callback method requires access to non-public methods and/or fields of the class.
The external listener callback mechanism enables the registration of a Listener instance with a Marshaller#setListener(Listener) . The external listener receives all callback events, allowing for more centralized processing than per class defined callback methods.
The 'class defined' and external listener event callback methods are independent of each other, both can be called for one event. The invocation ordering when both listener callback methods exist is defined in Listener#beforeMarshal(Object) and Listener#afterMarshal(Object) .
An event callback method throwing an exception terminates the current marshal process.

Also see:

JAXBContext

Validator

Unmarshaller

author:

Kohsuke - Kawaguchi, Sun Microsystems, Inc.
Ryan Shoemaker, Sun Microsystems, Inc.
Joe Fialli, Sun Microsystems, Inc.

version: $ - Revision: 1.21 $ $Date: 2006/08/28 17:56:41 $

since: JAXB1.0 -

Nested Class Summary:
abstract public static class	Marshaller.Listener	Register an instance of an implementation of this class with a {@link Marshaller} to externally listen for marshal events. This class enables pre and post processing of each marshalled object. The event callbacks are called when marshalling from an instance that maps to an xml element or complex type definition. The event callbacks are not called when marshalling from an instance of a Java datatype that represents a simple type definition. External listener is one of two different mechanisms for defining marshal event callbacks. See Marshal Event Callbacks for an overview.

Nested Class Summary:

abstract public static class

Marshaller.Listener

Register an instance of an implementation of this class with a {@link Marshaller} to externally listen for marshal events.

This class enables pre and post processing of each marshalled object. The event callbacks are called when marshalling from an instance that maps to an xml element or complex type definition. The event callbacks are not called when marshalling from an instance of a Java datatype that represents a simple type definition.

External listener is one of two different mechanisms for defining marshal event callbacks. See Marshal Event Callbacks for an overview.

Field Summary
public static final String	JAXB_ENCODING	The name of the property used to specify the output encoding in the marshalled XML data.
public static final String	JAXB_FORMATTED_OUTPUT	The name of the property used to specify whether or not the marshalled XML data is formatted with linefeeds and indentation.
public static final String	JAXB_SCHEMA_LOCATION	The name of the property used to specify the xsi:schemaLocation attribute value to place in the marshalled XML output.
public static final String	JAXB_NO_NAMESPACE_SCHEMA_LOCATION	The name of the property used to specify the xsi:noNamespaceSchemaLocation attribute value to place in the marshalled XML output.
public static final String	JAXB_FRAGMENT	The name of the property used to specify whether or not the marshaller will generate document level events (ie calling startDocument or endDocument).

Method from javax.xml.bind.Marshaller Summary:
getAdapter, getAttachmentMarshaller, getEventHandler, getListener, getNode, getProperty, getSchema, marshal, marshal, marshal, marshal, marshal, marshal, marshal, marshal, setAdapter, setAdapter, setAttachmentMarshaller, setEventHandler, setListener, setProperty, setSchema

Method from javax.xml.bind.Marshaller Detail:
public A getAdapter(Class<A> type) Gets the adapter associated with the specified type. This is the reverse operation of the #setAdapter method.
public AttachmentMarshaller getAttachmentMarshaller()
public ValidationEventHandler getEventHandler() throws JAXBException Return the current event handler or the default event handler if one hasn't been set.
public Listener getListener() Return Listener registered with this Marshaller .
public Node getNode(Object contentTree) throws JAXBException Get a DOM tree view of the content tree(Optional). If the returned DOM tree is updated, these changes are also visible in the content tree. Use #marshal(Object, org.w3c.dom.Node) to force a deep copy of the content tree to a DOM representation.
public Object getProperty(String name) throws PropertyException Get the particular property in the underlying implementation of `Marshaller`. This method can only be used to get one of the standard JAXB defined properties above or a provider specific property. Attempting to get an undefined property will result in a PropertyException being thrown. See Supported Properties.
public Schema getSchema() Get the JAXP 1.3 Schema object being used to perform marshal-time validation. If there is no Schema set on the marshaller, then this method will return null indicating that marshal-time validation will not be performed.
public void marshal(Object jaxbElement, Result result) throws JAXBException Marshal the content tree rooted at `jaxbElement` into the specified `javax.xml.transform.Result`. All JAXB Providers must at least support javax.xml.transform.dom.DOMResult , javax.xml.transform.sax.SAXResult , and javax.xml.transform.stream.StreamResult . It can support other derived classes of `Result` as well.
public void marshal(Object jaxbElement, OutputStream os) throws JAXBException Marshal the content tree rooted at `jaxbElement` into an output stream.
public void marshal(Object jaxbElement, File output) throws JAXBException Marshal the content tree rooted at `jaxbElement` into a file.
public void marshal(Object jaxbElement, Writer writer) throws JAXBException Marshal the content tree rooted at `jaxbElement` into a Writer.
public void marshal(Object jaxbElement, ContentHandler handler) throws JAXBException Marshal the content tree rooted at `jaxbElement` into SAX2 events.
public void marshal(Object jaxbElement, Node node) throws JAXBException Marshal the content tree rooted at `jaxbElement` into a DOM tree.
public void marshal(Object jaxbElement, XMLStreamWriter writer) throws JAXBException Marshal the content tree rooted at `jaxbElement` into a javax.xml.stream.XMLStreamWriter .
public void marshal(Object jaxbElement, XMLEventWriter writer) throws JAXBException Marshal the content tree rooted at `jaxbElement` into a javax.xml.stream.XMLEventWriter .
public void setAdapter(XmlAdapter adapter) Associates a configured instance of XmlAdapter with this marshaller. This is a convenience method that invokes `setAdapter(adapter.getClass(),adapter);`.
public void setAdapter(Class<A> type, A adapter) Associates a configured instance of XmlAdapter with this marshaller. Every marshaller internally maintains a java.util.Map <Class ,XmlAdapter >, which it uses for marshalling classes whose fields/methods are annotated with javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter . This method allows applications to use a configured instance of XmlAdapter . When an instance of an adapter is not given, a marshaller will create one by invoking its default constructor.
public void setAttachmentMarshaller(AttachmentMarshaller am) Associate a context that enables binary data within an XML document to be transmitted as XML-binary optimized attachment. The attachment is referenced from the XML document content model by content-id URIs(cid) references stored within the xml document.
public void setEventHandler(ValidationEventHandler handler) throws JAXBException Allow an application to register a validation event handler. The validation event handler will be called by the JAXB Provider if any validation errors are encountered during calls to any of the marshal API's. If the client application does not register a validation event handler before invoking one of the marshal methods, then validation events will be handled by the default event handler which will terminate the marshal operation after the first error or fatal error is encountered. Calling this method with a null parameter will cause the Marshaller to revert back to the default default event handler.
public void setListener(Listener listener) Register marshal event callback Listener with this Marshaller . There is only one Listener per Marshaller. Setting a Listener replaces the previous set Listener. One can unregister current Listener by setting listener to `null`.
public void setProperty(String name, Object value) throws PropertyException Set the particular property in the underlying implementation of `Marshaller`. This method can only be used to set one of the standard JAXB defined properties above or a provider specific property. Attempting to set an undefined property will result in a PropertyException being thrown. See Supported Properties.
public void setSchema(Schema schema) Specify the JAXP 1.3 Schema object that should be used to validate subsequent marshal operations against. Passing null into this method will disable validation. This method allows the caller to validate the marshalled XML as it's marshalled. Initially this property is set to `null`.