org.dom4j
Interface Node

All Superinterfaces:

Cloneable

All Known Subinterfaces:

Attribute, Branch, CDATA, CharacterData, Comment, Document, DocumentType, Element, Entity, ProcessingInstruction, Text

All Known Implementing Classes:

AbstractAttribute, AbstractBranch, AbstractCDATA, AbstractCharacterData, AbstractComment, AbstractDocument, AbstractDocumentType, AbstractElement, AbstractEntity, AbstractNode, AbstractProcessingInstruction, AbstractText, FlyweightCDATA, FlyweightComment, FlyweightText

public interface Node

extends Cloneable

Node defines the polymorphic behavior for all XML nodes in a dom4j tree.

A node can be output as its XML format, can be detached from its position in a document and can have XPath expressions evaluated on itself.

A node may optionally support the parent relationship and may be read only.

Version:

$Revision: 1.31 $

Author:

James Strachan

See Also:

supportsParent(), isReadOnly()

Field Summary

static short	ANY_NODE Matches Element nodes
static short	ATTRIBUTE_NODE Matches elements nodes
static short	CDATA_SECTION_NODE Matches elements nodes
static short	COMMENT_NODE Matches Comments nodes
static short	DOCUMENT_NODE Matches Document nodes
static short	DOCUMENT_TYPE_NODE Matches DocumentType nodes
static short	ELEMENT_NODE Matches Element nodes
static short	ENTITY_REFERENCE_NODE Matches elements nodes
static short	MAX_NODE_TYPE The maximum number of node types for sizing purposes
static short	NAMESPACE_NODE Matchs a Namespace Node - NOTE this differs from DOM
static short	PROCESSING_INSTRUCTION_NODE Matches ProcessingInstruction
static short	TEXT_NODE Matches elements nodes
static short	UNKNOWN_NODE Does not match any valid node

Method Summary

void	accept(Visitor visitor) accept is the method used in the Visitor Pattern.
String	asXML() asXML returns the textual XML representation of this node.
Node	asXPathResult(Element parent) asXPathResult returns a version of this node which is capable of being an XPath result.
Object	clone() clone will return a deep clone or if this node is read-only then clone will return the same instance.
XPath	createXPath(String xpathExpression) createXPath creates an XPath object for the given xpathExpression.
Node	detach() Removes this node from its parent if there is one.
Document	getDocument() getDocument returns the Document that this Node is part of if this node supports the parent relationship.
String	getName() getName returns the name of this node.
short	getNodeType() Returns the code according to the type of node.
String	getNodeTypeName() DOCUMENT ME!
Element	getParent() getParent returns the parent Element if this node supports the parent relationship or null if it is the root element or does not support the parent relationship.
String	getPath() Returns the XPath expression which will return a node set containing the given node such as /a/b/@c.
String	getPath(Element context) Returns the relative XPath expression which will return a node set containing the given node such as a/b/@c.
String	getStringValue() Returns the XPath string-value of this node.
String	getText() Returns the text of this node.
String	getUniquePath() Returns the XPath expression which will return a nodeset of one node which is the current node.
String	getUniquePath(Element context) Returns the relative unique XPath expression from the given context which will return a nodeset of one node which is the current node.
boolean	hasContent() hasContent returns true if this node is a Branch (either an Element or a Document) and it contains at least one content node such as a child Element or Text node.
boolean	isReadOnly() isReadOnly returns true if this node is read only and cannot be modified.
boolean	matches(String xpathExpression) matches returns true if evaluating the given XPath expression on this node returns a non-empty node set containing this node.
Number	numberValueOf(String xpathExpression) numberValueOf evaluates an XPath expression and returns the numeric value of the XPath expression if the XPath expression results in a number, or null if the result is not a number.
List	selectNodes(String xpathExpression) selectNodes evaluates an XPath expression and returns the result as a List of Node instances or String instances depending on the XPath expression.
List	selectNodes(String xpathExpression, String comparisonXPathExpression) selectNodes evaluates an XPath expression then sorts the results using a secondary XPath expression Returns a sorted List of Node instances.
List	selectNodes(String xpathExpression, String comparisonXPathExpression, boolean removeDuplicates) selectNodes evaluates an XPath expression then sorts the results using a secondary XPath expression Returns a sorted List of Node instances.
Object	selectObject(String xpathExpression) selectObject evaluates an XPath expression and returns the result as an Object.
Node	selectSingleNode(String xpathExpression) selectSingleNode evaluates an XPath expression and returns the result as a single Node instance.
void	setDocument(Document document) setDocument sets the document of this node if the parent relationship is supported or does nothing if the parent relationship is not supported.
void	setName(String name) Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only.
void	setParent(Element parent) setParent sets the parent relationship of this node if the parent relationship is supported or does nothing if the parent relationship is not supported.
void	setText(String text) Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only.
boolean	supportsParent() supportsParent returns true if this node supports the parent relationship.
String	valueOf(String xpathExpression) valueOf evaluates an XPath expression and returns the textual representation of the results the XPath string-value of this node.
void	write(Writer writer) write writes this node as the default XML notation for this node.

Field Detail

ANY_NODE

public static final short ANY_NODE

Matches Element nodes

See Also:

Constant Field Values

ELEMENT_NODE

public static final short ELEMENT_NODE

Matches Element nodes

See Also:

Constant Field Values

ATTRIBUTE_NODE

public static final short ATTRIBUTE_NODE

Matches elements nodes

See Also:

Constant Field Values

TEXT_NODE

public static final short TEXT_NODE

Matches elements nodes

See Also:

Constant Field Values

CDATA_SECTION_NODE

public static final short CDATA_SECTION_NODE

Matches elements nodes

See Also:

Constant Field Values

ENTITY_REFERENCE_NODE

public static final short ENTITY_REFERENCE_NODE

Matches elements nodes

See Also:

Constant Field Values

PROCESSING_INSTRUCTION_NODE

public static final short PROCESSING_INSTRUCTION_NODE

Matches ProcessingInstruction

See Also:

Constant Field Values

COMMENT_NODE

public static final short COMMENT_NODE

Matches Comments nodes

See Also:

Constant Field Values

DOCUMENT_NODE

public static final short DOCUMENT_NODE

Matches Document nodes

See Also:

Constant Field Values

DOCUMENT_TYPE_NODE

public static final short DOCUMENT_TYPE_NODE

Matches DocumentType nodes

See Also:

Constant Field Values

NAMESPACE_NODE

public static final short NAMESPACE_NODE

Matchs a Namespace Node - NOTE this differs from DOM

See Also:

Constant Field Values

UNKNOWN_NODE

public static final short UNKNOWN_NODE

Does not match any valid node

See Also:

Constant Field Values

MAX_NODE_TYPE

public static final short MAX_NODE_TYPE

The maximum number of node types for sizing purposes

See Also:

Constant Field Values

Method Detail

supportsParent

public boolean supportsParent()

supportsParent returns true if this node supports the parent relationship.

Some XML tree implementations are singly linked and only support downward navigation through children relationships. The default case is that both parent and children relationships are supported though for memory and performance reasons the parent relationship may not be supported.

Returns:

true if this node supports the parent relationship or false it is not supported

getParent

public Element getParent()

getParent returns the parent Element if this node supports the parent relationship or null if it is the root element or does not support the parent relationship.

This method is an optional feature and may not be supported for all Node implementations.

Returns:

the parent of this node or null if it is the root of the tree or the parent relationship is not supported.

setParent

public void setParent(Element parent)

setParent sets the parent relationship of this node if the parent relationship is supported or does nothing if the parent relationship is not supported.

This method should only be called from inside an Element implementation method and is not intended for general use.

Parameters:

parent - is the new parent of this node.

getDocument

public Document getDocument()

getDocument returns the Document that this Node is part of if this node supports the parent relationship.

This method is an optional feature and may not be supported for all Node implementations.

Returns:

the document of this node or null if this feature is not supported or the node is not associated with a Document

setDocument

public void setDocument(Document document)

setDocument sets the document of this node if the parent relationship is supported or does nothing if the parent relationship is not supported.

This method should only be called from inside a Document implementation method and is not intended for general use.

Parameters:

document - is the new document of this node.

isReadOnly

public boolean isReadOnly()

isReadOnly returns true if this node is read only and cannot be modified. Any attempt to modify a read-only Node will result in an UnsupportedOperationException being thrown.

Returns:

true if this Node is read only and cannot be modified otherwise false.

hasContent

public boolean hasContent()

hasContent returns true if this node is a Branch (either an Element or a Document) and it contains at least one content node such as a child Element or Text node.

Returns:

true if this Node is a Branch with a nodeCount() of one or more.

getName

public String getName()

getName returns the name of this node. This is the XML local name of the element, attribute, entity or processing instruction. For CDATA and Text nodes this method will return null.

Returns:

the XML name of this node

setName

public void setName(String name)

Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only.

Parameters:

name - is the new name of this node

getText

public String getText()

Returns the text of this node.

Returns:

the text for this node.

setText

public void setText(String text)

Sets the text data of this node or this method will throw an UnsupportedOperationException if it is read-only.

Parameters:

text - is the new textual value of this node

getStringValue

public String getStringValue()

Returns the XPath string-value of this node. The behaviour of this method is defined in the XPath specification .

Returns:

the text from all the child Text and Element nodes appended together.

getPath

public String getPath()

Returns the XPath expression which will return a node set containing the given node such as /a/b/@c. No indexing will be used to restrict the path if multiple elements with the same name occur on the path.

Returns:

the XPath expression which will return a nodeset containing at least this node.

getPath

public String getPath(Element context)

Returns the relative XPath expression which will return a node set containing the given node such as a/b/@c. No indexing will be used to restrict the path if multiple elements with the same name occur on the path.

Parameters:

context - is the parent context from which the relative path should start. If the context is null or the context is not an ancestor of this node then the path will be absolute and start from the document and so begin with the '/' character.

Returns:

the XPath expression relative to the given context which will return a nodeset containing at least this node.

getUniquePath

public String getUniquePath()

Returns the XPath expression which will return a nodeset of one node which is the current node. This method will use the XPath index operator to restrict the path if multiple elements with the same name occur on the path.

Returns:

the XPath expression which will return a nodeset containing just this node.

getUniquePath

public String getUniquePath(Element context)

Returns the relative unique XPath expression from the given context which will return a nodeset of one node which is the current node. This method will use the XPath index operator to restrict the path if multiple elements with the same name occur on the path.

Parameters:

context - is the parent context from which the path should start. If the context is null or the context is not an ancestor of this node then the path will start from the document and so begin with the '/' character.

Returns:

the XPath expression relative to the given context which will return a nodeset containing just this node.

asXML

public String asXML()

asXML returns the textual XML representation of this node.

Returns:

the XML representation of this node

write

public void write(Writer writer)
           throws IOException

write writes this node as the default XML notation for this node. If you wish to control the XML output (such as for pretty printing, changing the indentation policy etc.) then please use XMLWriter or its derivations.

Parameters:

writer - is the Writer to output the XML to

Throws:

IOException - DOCUMENT ME!

getNodeType

public short getNodeType()

Returns the code according to the type of node. This makes processing nodes polymorphically much easier as the switch statement can be used instead of multiple if (instanceof) statements.

Returns:

a W3C DOM complient code for the node type such as ELEMENT_NODE or ATTRIBUTE_NODE

getNodeTypeName

public String getNodeTypeName()

DOCUMENT ME!

Returns:

the name of the type of node such as "Document", "Element", "Attribute" or "Text"

detach

public Node detach()

Removes this node from its parent if there is one. If this node is the root element of a document then it is removed from the document as well.

This method is useful if you want to remove a node from its source document and add it to another document. For example

Node node = ...; Element someOtherElement = ...; someOtherElement.add( node.detach() );

Returns:

the node that has been removed from its parent node if any and its document if any.

selectNodes

public List selectNodes(String xpathExpression)

selectNodes evaluates an XPath expression and returns the result as a List of Node instances or String instances depending on the XPath expression.

Parameters:

xpathExpression - is the XPath expression to be evaluated

Returns:

the list of Node or String instances depending on the XPath expression

selectObject

public Object selectObject(String xpathExpression)

selectObject evaluates an XPath expression and returns the result as an Object. The object returned can either be a List of one or more Nodeinstances or a scalar object like a Stringor a Numberinstance depending on the XPath expression.

Parameters:

xpathExpression - is the XPath expression to be evaluated

Returns:

the value of the XPath expression as a Listof Node instances, a Stringor a Numberinstance depending on the XPath expression.

selectNodes

public List selectNodes(String xpathExpression,
                        String comparisonXPathExpression)

selectNodes evaluates an XPath expression then sorts the results using a secondary XPath expression Returns a sorted List of Node instances.

Parameters:

xpathExpression - is the XPath expression to be evaluated

comparisonXPathExpression - is the XPath expression used to compare the results by for sorting

Returns:

the list of Node instances sorted by the comparisonXPathExpression

selectNodes

public List selectNodes(String xpathExpression,
                        String comparisonXPathExpression,
                        boolean removeDuplicates)

selectNodes evaluates an XPath expression then sorts the results using a secondary XPath expression Returns a sorted List of Node instances.

Parameters:

xpathExpression - is the XPath expression to be evaluated

comparisonXPathExpression - is the XPath expression used to compare the results by for sorting

removeDuplicates - if this parameter is true then duplicate values (using the comparisonXPathExpression) are removed from the result List.

Returns:

the list of Node instances sorted by the comparisonXPathExpression

selectSingleNode

public Node selectSingleNode(String xpathExpression)

selectSingleNode evaluates an XPath expression and returns the result as a single Node instance.

Parameters:

xpathExpression - is the XPath expression to be evaluated

Returns:

the Node matching the XPath expression

valueOf

public String valueOf(String xpathExpression)

valueOf evaluates an XPath expression and returns the textual representation of the results the XPath string-value of this node. The string-value for a given node type is defined in the XPath specification .

Parameters:

xpathExpression - is the XPath expression to be evaluated

Returns:

the string-value representation of the results of the XPath expression

numberValueOf

public Number numberValueOf(String xpathExpression)

numberValueOf evaluates an XPath expression and returns the numeric value of the XPath expression if the XPath expression results in a number, or null if the result is not a number.

Parameters:

xpathExpression - is the XPath expression to be evaluated

Returns:

the numeric result of the XPath expression or null if the result is not a number.

matches

public boolean matches(String xpathExpression)

matches returns true if evaluating the given XPath expression on this node returns a non-empty node set containing this node.

This method does not behave like the <xsl:if> element - if you want that behaviour, to evaluate if an XPath expression matches something, then you can use the following code to be equivalent...

if ( node.selectSingleNode( "/some/path" ) != nulll )

Parameters:

xpathExpression - is an XPath expression

Returns:

true if this node is returned by the given XPath expression

createXPath

public XPath createXPath(String xpathExpression)
                  throws InvalidXPathException

createXPath creates an XPath object for the given xpathExpression. The XPath object allows the variable context to be specified.

Parameters:

xpathExpression - is the XPath expression to be evaluated

Returns:

an XPath object represeting the given expression

Throws:

InvalidXPathException - if the XPath expression is invalid

asXPathResult

public Node asXPathResult(Element parent)

asXPathResult returns a version of this node which is capable of being an XPath result. The result of an XPath expression should always support the parent relationship, whether the original XML tree was singly or doubly linked. If the node does not support the parent relationship then a new node will be created which is linked to its parent and returned.

Parameters:

parent - DOCUMENT ME!

Returns:

a Node which supports the parent relationship

accept

public void accept(Visitor visitor)

accept is the method used in the Visitor Pattern.

Parameters:

visitor - is the visitor in the Visitor Pattern

clone

public Object clone()

clone will return a deep clone or if this node is read-only then clone will return the same instance.

Returns:

a deep clone of myself or myself if I am read only.