Class NamespaceDifferencer

  • All Implemented Interfaces:
    javax.xml.transform.Result, Receiver

    public class NamespaceDifferencer
    extends ProxyReceiver

    NamespaceDifferencer is a ProxyReceiver responsible for removing duplicate namespace declarations. It also ensures that namespace undeclarations are emitted when necessary.

    The NamespaceDifferencer assumes that in the input event stream, all in-scope namespaces for every element are accounted for in the call on namespace(). In the output event stream, the namespace() call represents namespace declarations rather than in-scope namespaces. So (a) redundant namespaces are removed, and (b) namespace undeclarations are added where necessary. A namespace undeclaration for the default namespace is always added if the parent element has a default namespace and the child element does not; namespace undeclarations for other namespaces are emitted only when the serialization option undeclare-namespaces is set.

    The NamespaceDifferencer is part of the serialization pipeline, responsible for translating result trees to serialized XML. As such, it is not concerned with operations such as namespace fixup and namespace inheritance that are part of the result tree construction process.

    The NamespaceDifferencer is also needed when writing output to tree models such as DOM and JDOM that require local namespace declarations to be provided for each element node.

    • Constructor Detail

      • NamespaceDifferencer

        public NamespaceDifferencer​(Receiver next,
                                    java.util.Properties details)
        Create a NamespaceDeclarer
        next - the Receiver to which events will be passed after namespace reduction
    • Method Detail

      • startElement

        public void startElement​(NodeName elemName,
                                 SchemaType type,
                                 AttributeMap attributes,
                                 NamespaceMap namespaces,
                                 Location location,
                                 int properties)
                          throws XPathException
        startElement. This call removes redundant namespace declarations, and possibly adds an xmlns="" undeclaration.
        Specified by:
        startElement in interface Receiver
        startElement in class ProxyReceiver
        elemName - the name of the element.
        type - the type annotation of the element.
        attributes - the attributes of this element
        namespaces - the in-scope namespaces of this element: generally this is all the in-scope namespaces, without relying on inheriting namespaces from parent elements
        location - an object providing information about the module, line, and column where the node originated
        properties - bit-significant properties of the element node. If there are no relevant properties, zero is supplied. The definitions of the bits are in class ReceiverOption
        XPathException - if an error occurs