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The Attr interface represents an attribute in an
Element object. Typically the allowable values for the
attribute are defined in a document type definition.
Attr objects inherit the Node interface, but
since they are not actually child nodes of the element they describe, the
DOM does not consider them part of the document tree. Thus, the
Node attributes parentNode,
previousSibling, and nextSibling have a
null value for Attr objects. The DOM takes the
view that attributes are properties of elements rather than having a
separate identity from the elements they are associated with; this should
make it more efficient to implement such features as default attributes
associated with all elements of a given type. Furthermore,
Attr nodes may not be immediate children of a
DocumentFragment. However, they can be associated with
Element nodes contained within a
DocumentFragment. In short, users and implementors of the
DOM need to be aware that Attr nodes have some things in
common with other objects inheriting the Node interface, but
they also are quite distinct.
The attribute's effective value is determined as follows: if this
attribute has been explicitly assigned any value, that value is the
attribute's effective value; otherwise, if there is a declaration for
this attribute, and that declaration includes a default value, then that
default value is the attribute's effective value; otherwise, the
attribute does not exist on this element in the structure model until it
has been explicitly added. Note that the nodeValue attribute
on the Attr instance can also be used to retrieve the string
version of the attribute's value(s).
In XML, where the value of an attribute can contain entity references,
the child nodes of the Attr node may be either
Text or EntityReference nodes (when these are
in use; see the description of EntityReference for
discussion). Because the DOM Core is not aware of attribute types, it
treats all attribute values as simple strings, even if the DTD or schema
declares them as having tokenized types.
See also the Document Object Model (DOM) Level 2 Core Specification.
| Field Summary |
| Fields inherited from interface org.w3c.dom.Node |
ATTRIBUTE_NODE, CDATA_SECTION_NODE, COMMENT_NODE, DOCUMENT_FRAGMENT_NODE, DOCUMENT_NODE, DOCUMENT_TYPE_NODE, ELEMENT_NODE, ENTITY_NODE, ENTITY_REFERENCE_NODE, NOTATION_NODE, PROCESSING_INSTRUCTION_NODE, TEXT_NODE |
| Method Summary | ||
String |
getName()
Returns the name of this attribute. |
|
Element |
getOwnerElement()
The Element node this attribute is attached to or
null if this attribute is not in use. |
|
boolean |
getSpecified()
If this attribute was explicitly given a value in the original document, this is true; otherwise, it is
false. |
|
String |
getValue()
On retrieval, the value of the attribute is returned as a string. |
|
boolean |
isId()
Returns whether this attribute is known to be of type ID (i.e. to contain an identifier for its owner element) or not. |
|
void |
setValue(String value)
On retrieval, the value of the attribute is returned as a string. |
|
| Methods inherited from interface org.w3c.dom.Node |
appendChild, cloneNode, getAttributes, getChildNodes, getFirstChild, getLastChild, getLocalName, getNamespaceURI, getNextSibling, getNodeName, getNodeType, getNodeValue, getOwnerDocument, getParentNode, getPrefix, getPreviousSibling, hasAttributes, hasChildNodes, insertBefore, isSupported, normalize, removeChild, replaceChild, setNodeValue, setPrefix |
| Method Detail |
public Element getOwnerElement()
Element node this attribute is attached to or
null if this attribute is not in use.public boolean getSpecified()
true; otherwise, it is
false. Note that the implementation is in charge of this
attribute, not the user. If the user changes the value of the
attribute (even if it ends up having the same value as the default
value) then the specified flag is automatically flipped
to true. To re-specify the attribute as the default
value from the DTD, the user must delete the attribute. The
implementation will then make a new attribute available with
specified set to false and the default
value (if one exists).
specified is true, and the value is
the assigned value.If the attribute has no assigned value in the
document and has a default value in the DTD, then
specified is false, and the value is the
default value in the DTD.If the attribute has no assigned value in
the document and has a value of #IMPLIED in the DTD, then the
attribute does not appear in the structure model of the document.If
the ownerElement attribute is null (i.e.
because it was just created or was set to null by the
various removal and cloning operations) specified is
true.public String getValue()
getAttribute on the
Element interface.
Text node with the unparsed
contents of the string. I.e. any characters that an XML processor
would recognize as markup are instead treated as literal text. See
also the method setAttribute on the Element
interface.DOMException - NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.public boolean isId()
ownerElement of this attribute
can be retrieved using the method Document.getElementById
. The implementation could use several ways to determine if an
attribute node is known to contain an identifier:
Document.normalizeDocument(), the post-schema-validation
infoset contributions (PSVI contributions) values are used to
determine if this attribute is a schema-determined ID attribute using
the
schema-determined ID definition in [XPointer]
.
Document.normalizeDocument(), the infoset [type definition] value is used to determine if this attribute is a DTD-determined ID
attribute using the
DTD-determined ID definition in [XPointer]
.
Element.setIdAttribute(),
Element.setIdAttributeNS(), or
Element.setIdAttributeNode(), i.e. it is an
user-determined ID attribute;
Note: XPointer framework (see section 3.2 in [XPointer] ) consider the DOM user-determined ID attribute as being part of the XPointer externally-determined ID definition.
Document.normalizeDocument(), all user-determined ID
attributes are reset and all attribute nodes ID information are then
reevaluated in accordance to the schema used. As a consequence, if
the Attr.schemaTypeInfo attribute contains an ID type,
isId will always return true.public void setValue(String value) throws DOMException
getAttribute on the
Element interface.
Text node with the unparsed
contents of the string. I.e. any characters that an XML processor
would recognize as markup are instead treated as literal text. See
also the method setAttribute on the Element
interface.DOMException - NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.
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