org.jdom2

Interface NamespaceAware

All Known Subinterfaces:

Parent

All Known Implementing Classes:

Attribute, CDATA, Comment, Content, DocType, Document, Element, EntityRef, LocatedCDATA, LocatedComment, LocatedDocType, LocatedElement, LocatedEntityRef, LocatedProcessingInstruction, LocatedText, ProcessingInstruction, Text

public interface NamespaceAware

Classes implementing this interface are all sensitive to their Namespace context. All the core JDOM classes are NamespaceAware (Parent and subtypes, Content and subtypes, and Attribute). You can use the methods that this interface provides to query the Namespace context.

JDOM2 introduces a consistency in reporting Namespace context. XML standards do not dictate any conditions on Namespace reporting or ordering, but consistency is valuable for user-friendliness. As a result JDOM2 imposes a useful order on the Namespace context for XML content.

The order for Namespace reporting is:

1. If the item 'has' a Namespace (Element, Attribute) then that Namespace is reported.
2. The remaining Namespaces are reported in alphabetical order by prefix.

The XML namespace (bound to the prefix "xml" - see Namespace.XML_NAMESPACE ) is always in every scope. It is always introduced in Document, and in all other NamespaceAware instances it is introduced if that content is detached.

See the individualised documentation for each implementing type for additional specific details. The following section is a description of how Namespaces are managed in the Element class.

The Element Namespace Scope

The 'default' Namespace is a source of confusion, but it is simply the Namespace which is in-scope for an Element that has no Namespace prefix (prefix is "" but it could have any Namespace URI). There will always be exactly one Namespace that is in-scope for an element that has no prefix.

All Elements are in a Namespace. Elements will be in Namespace.NO_NAMESPACE unless a different Namespace was supplied as part of the Element Constructor, or later modified by the Element.setNamespace(Namespace) method.

In addition to the Element's Namespace, there could be other Namespaces that are 'in scope' for the Element. The set of Namespaces that are in scope for an Element is the union of five sets:

XML	There is always exactly one member of this set, Namespace.XML_NAMESPACE. This set cannot be changed.
Element	There is always exactly one member of this set, and it can be retrieved or set with the methods Element.getNamespace() and Element.setNamespace(Namespace) respectively.
Attribute	This is the set of distinct Namespaces that are used on Attributes. You can modify the set by adding and removing Attributes to the Element. NOTE: The Namespace.NO_NAMESPACE Namespace is always the default Namespace for attributes (the Namespace that has no prefix). Thus there may be a special case with this Namespace, because if there is a different default Namespace for the Element, then the Namespace.NO_NAMESPACE Namespace is not part of the Element's in-scope Namespace set (the Element cannot have two Namespaces in scope with the same prefix - "").
Additional	This set is maintained by the two methods Element.addNamespaceDeclaration(Namespace) and Element.removeNamespaceDeclaration(Namespace). You can get the full set of additional Namespaces with Element.getAdditionalNamespaces()
Inherited	This last set is somewhat dynamic because only those Namespaces on the parent Element which are not re-defined by this Element will be inherited. A Namespace is redefined by setting a new Namespace with the same prefix, but a different URI. If you set a Namespace on the Element (or add a Namespace declaration or set an Attribute) with the same prefix as another Namespace that would have been otherwise inherited, then that other Namespace will no longer be inherited.

Since you cannot change the Namespace.XML_NAMESPACE, and the 'inherited' Namespace set is dynamic, the remaining Namespace sets are the most interesting from a JDOM perspective. JDOM validates all modifications that affect the Namespaces in scope for an Element. An IllegalAddException will be thrown if you attempt to add a new Namespace to the in-scope set if a different Namespace with the same prefix is already part of one of these three sets (Element, Attribute, or Additional).

Since:

JDOM2

Author:

Rolf Lear

Method Summary

Modifier and Type	Method and Description
java.util.List<Namespace>	getNamespacesInherited() Obtain a list of all namespaces that are in scope for this content, but were not introduced by this content.
java.util.List<Namespace>	getNamespacesInScope() Obtain a list of all namespaces that are in scope for the current content.
java.util.List<Namespace>	getNamespacesIntroduced() Obtain a list of all namespaces that are introduced to the XML tree by this node.

Method Detail

getNamespacesInScope

java.util.List<Namespace> getNamespacesInScope()

Obtain a list of all namespaces that are in scope for the current content.

The contents of this list will always be the combination of getNamespacesIntroduced() and getNamespacesInherited().

See NamespaceAware documentation for details on what the order of the Namespaces will be in the returned list.

Returns:

a read-only list of Namespaces.

getNamespacesIntroduced

java.util.List<Namespace> getNamespacesIntroduced()

Obtain a list of all namespaces that are introduced to the XML tree by this node. Only Elements and Attributes can introduce namespaces, so all other Content types will return an empty list.

The contents of this list will always be a subset (but in the same order) of getNamespacesInScope(), and will never intersect getNamspacesInherited()

Returns:

a read-only list of Namespaces.

getNamespacesInherited

java.util.List<Namespace> getNamespacesInherited()

Obtain a list of all namespaces that are in scope for this content, but were not introduced by this content.

The contents of this list will always be a subset (but in the same order) of getNamespacesInScope(), and will never intersect getNamspacesIntroduced()

Returns:

a read-only list of Namespaces.