org.htmlparser
Class AbstractNode

java.lang.Object
  org.htmlparser.AbstractNode

All Implemented Interfaces:

Node, Serializable

Direct Known Subclasses:

RemarkNode, StringNode, TagNode

public abstract class AbstractNode

extends Object

implements Node, Serializable

AbstractNode, which implements the Node interface, is the base class for all types of nodes, including tags, string elements, etc

See Also:

Serialized Form

Field Summary

protected NodeList	children The children of this node.
protected Page	mPage The page this node came from.
protected int	nodeBegin The beginning position of the tag in the line
protected int	nodeEnd The ending position of the tag in the line
protected Node	parent The parent of this node.

Constructor Summary

AbstractNode(Page page, int start, int end)
Create an abstract node with the page positions given.

Method Summary

abstract void	accept(Object visitor) Apply the visitor object (of type NodeVisitor) to this node.
void	collectInto(NodeList list, NodeFilter filter) Collect this node and its child nodes (if-applicable) into the collectionList parameter, provided the node satisfies the filtering criteria.
void	doSemanticAction() Perform the meaning of this tag.
int	elementBegin() Deprecated. Use getStartPosition().
int	elementEnd() Deprecated. Use getEndPosition().
NodeList	getChildren() Get the children of this node.
int	getEndPosition() Gets the ending position of the node.
Page	getPage() Get the page this node came from.
Node	getParent() Get the parent of this node.
int	getStartPosition() Gets the starting position of the node.
String	getText() Returns the text of the string line
void	setChildren(NodeList children) Set the children of this node.
void	setEndPosition(int position) Sets the ending position of the node.
void	setPage(Page page) Set the page this node came from.
void	setParent(Node node) Sets the parent of this node.
void	setStartPosition(int position) Sets the starting position of the node.
void	setText(String text) Sets the string contents of the node.
abstract String	toHtml() This method will make it easier when using html parser to reproduce html pages (with or without modifications) Applications reproducing html can use this method on nodes which are to be used or transferred as they were recieved, with the original html
String	toHTML() Deprecated. - use toHtml() instead
abstract String	toPlainTextString() Returns a string representation of the node.
abstract String	toString() Return the string representation of the node.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

mPage

protected Page mPage

The page this node came from.

nodeBegin

protected int nodeBegin

The beginning position of the tag in the line

nodeEnd

protected int nodeEnd

The ending position of the tag in the line

parent

protected Node parent

The parent of this node.

children

protected NodeList children

The children of this node.

Constructor Detail

AbstractNode

public AbstractNode(Page page,
                    int start,
                    int end)

Create an abstract node with the page positions given. Remember the page and start & end cursor positions.

Parameters:

page - The page this tag was read from.

start - The starting offset of this node within the page.

end - The ending offset of this node within the page.

Method Detail

toPlainTextString

public abstract String toPlainTextString()

Returns a string representation of the node. This is an important method, it allows a simple string transformation of a web page, regardless of a node.
Typical application code (for extracting only the text from a web page) would then be simplified to :

 Node node;
 for (Enumeration e = parser.elements();e.hasMoreElements();) {
    node = (Node)e.nextElement();
    System.out.println(node.toPlainTextString()); // Or do whatever processing you wish with the plain text string
 }
 

Specified by:

toPlainTextString in interface Node

toHtml

public abstract String toHtml()

This method will make it easier when using html parser to reproduce html pages (with or without modifications) Applications reproducing html can use this method on nodes which are to be used or transferred as they were recieved, with the original html

Specified by:

toHtml in interface Node

toString

public abstract String toString()

Return the string representation of the node. Subclasses must define this method, and this is typically to be used in the manner

System.out.println(node)

Specified by:

toString in interface Node

Returns:

java.lang.String

collectInto

public void collectInto(NodeList list,
                        NodeFilter filter)

Collect this node and its child nodes (if-applicable) into the collectionList parameter, provided the node satisfies the filtering criteria.

This mechanism allows powerful filtering code to be written very easily, without bothering about collection of embedded tags separately. e.g. when we try to get all the links on a page, it is not possible to get it at the top-level, as many tags (like form tags), can contain links embedded in them. We could get the links out by checking if the current node is a CompositeTag, and going through its children. So this method provides a convenient way to do this.

Using collectInto(), programs get a lot shorter. Now, the code to extract all links from a page would look like:

 NodeList collectionList = new NodeList();
 NodeFilter filter = new TagNameFilter ("A");
 for (NodeIterator e = parser.elements(); e.hasMoreNodes();)
      e.nextNode().collectInto(collectionList, filter);
 

Thus, collectionList will hold all the link nodes, irrespective of how deep the links are embedded.

Another way to accomplish the same objective is:

 NodeList collectionList = new NodeList();
 NodeFilter filter = new TagClassFilter (LinkTag.class);
 for (NodeIterator e = parser.elements(); e.hasMoreNodes();)
      e.nextNode().collectInto(collectionList, filter);
 

This is slightly less specific because the LinkTag class may be registered for more than one node name, e.g. <LINK> tags too.

Specified by:

collectInto in interface Node

elementBegin

public int elementBegin()

Deprecated. Use getStartPosition().

Returns the beginning position of the tag.

Specified by:

elementBegin in interface Node

elementEnd

public int elementEnd()

Deprecated. Use getEndPosition().

Returns the ending position fo the tag

Specified by:

elementEnd in interface Node

getPage

public Page getPage()

Get the page this node came from.

Returns:

The page that supplied this node.

setPage

public void setPage(Page page)

Set the page this node came from.

Parameters:

page - The page that supplied this node.

getStartPosition

public int getStartPosition()

Gets the starting position of the node.

Specified by:

getStartPosition in interface Node

Returns:

The start position.

setStartPosition

public void setStartPosition(int position)

Sets the starting position of the node.

Specified by:

setStartPosition in interface Node

Parameters:

position - The new start position.

getEndPosition

public int getEndPosition()

Gets the ending position of the node.

Specified by:

getEndPosition in interface Node

Returns:

The end position.

setEndPosition

public void setEndPosition(int position)

Sets the ending position of the node.

Specified by:

setEndPosition in interface Node

Parameters:

position - The new end position.

accept

public abstract void accept(Object visitor)

Description copied from interface: Node

Apply the visitor object (of type NodeVisitor) to this node.

Specified by:

accept in interface Node

toHTML

public final String toHTML()

Deprecated. - use toHtml() instead

getParent

public Node getParent()

Get the parent of this node. This will always return null when parsing without scanners, i.e. if semantic parsing was not performed. The object returned from this method can be safely cast to a CompositeTag.

Specified by:

getParent in interface Node

Returns:

The parent of this node, if it's been set, null otherwise.

setParent

public void setParent(Node node)

Sets the parent of this node.

Specified by:

setParent in interface Node

Parameters:

node - The node that contains this node. Must be a CompositeTag.

getChildren

public NodeList getChildren()

Get the children of this node.

Specified by:

getChildren in interface Node

Returns:

The list of children contained by this node, if it's been set, null otherwise.

setChildren

public void setChildren(NodeList children)

Set the children of this node.

Specified by:

setChildren in interface Node

Parameters:

children - The new list of children this node contains.

getText

public String getText()

Returns the text of the string line

Specified by:

getText in interface Node

setText

public void setText(String text)

Sets the string contents of the node.

Specified by:

setText in interface Node

Parameters:

text - The new text for the node.

doSemanticAction

public void doSemanticAction()
                      throws ParserException

Perform the meaning of this tag. The default action is to do nothing.

Specified by:

doSemanticAction in interface Node

Throws:

ParserException