gnu.xml.pipeline
Class LinkFilter

java.lang.Object
  |
  +--gnu.xml.pipeline.EventFilter
        |
        +--gnu.xml.pipeline.LinkFilter

All Implemented Interfaces:

ContentHandler, DeclHandler, DTDHandler, EventConsumer, LexicalHandler

public class LinkFilter

extends EventFilter

Pipeline filter to remember (X)HTML links found in an (X)HTML document, so they can later be crawled. Fragments are not counted, and duplicates are ignored. Callers are responsible for filtering out URLs they aren't interested in. Events are passed through unmodified.

Input MUST include a setDocumentLocator() call, as it's used to resolve relative links in the absence of a "base" element. Input MUST also include namespace identifiers, since it is the XHTML namespace identifier which is used to identify the relevant elements.

FIXME: handle xml:base attribute ... in association with a stack of base URIs. Similarly, recognize/support XLink data.

Version:

$Date: 2001/07/10 22:53:18 $

Author:

David Brownell

Fields inherited from class gnu.xml.pipeline.EventFilter

DECL_HANDLER, FEATURE_URI, LEXICAL_HANDLER, PROPERTY_URI

Constructor Summary

LinkFilter()
Constructs a new event filter, which collects links in private data structure for later enumeration.

LinkFilter(EventConsumer next)
Constructs a new event filter, which collects links in private data structure for later enumeration and passes all events, unmodified, to the next consumer.

Method Summary

void	endDocument() Forgets about any base URI information that may be recorded.
java.util.Enumeration	getLinks() Returns an enumeration of the links found since the filter was constructed, or since removeAllLinks() was called.
void	removeAllLinks() Removes records about all links reported to the event stream, as if the filter were newly created.
void	startDocument() Reports an error if no Locator has been made available.
void	startElement(java.lang.String namespace, java.lang.String local, java.lang.String name, Attributes attrs) Collects URIs for (X)HTML content from elements which hold them.

Methods inherited from class gnu.xml.pipeline.EventFilter

attributeDecl, bind, characters, comment, elementDecl, endCDATA, endDTD, endElement, endEntity, endPrefixMapping, externalEntityDecl, getContentHandler, getDocumentLocator, getDTDHandler, getErrorHandler, getNext, getProperty, ignorableWhitespace, internalEntityDecl, notationDecl, processingInstruction, setContentHandler, setDocumentLocator, setDTDHandler, setErrorHandler, setProperty, skippedEntity, startCDATA, startDTD, startEntity, startPrefixMapping, unparsedEntityDecl

Methods inherited from class java.lang.Object

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

Constructor Detail

LinkFilter

public LinkFilter()

Constructs a new event filter, which collects links in private data structure for later enumeration.

LinkFilter

public LinkFilter(EventConsumer next)

Constructs a new event filter, which collects links in private data structure for later enumeration and passes all events, unmodified, to the next consumer.

Method Detail

getLinks

public java.util.Enumeration getLinks()

Returns an enumeration of the links found since the filter was constructed, or since removeAllLinks() was called.

Returns:

enumeration of strings.

removeAllLinks

public void removeAllLinks()

Removes records about all links reported to the event stream, as if the filter were newly created.

startElement

public void startElement(java.lang.String namespace,
                         java.lang.String local,
                         java.lang.String name,
                         Attributes attrs)
                  throws SAXException

Collects URIs for (X)HTML content from elements which hold them.

Overrides:

startElement in class EventFilter

Following copied from interface: org.xml.sax.ContentHandler

Parameters:

uri - The Namespace URI, or the empty string if the element has no Namespace URI or if Namespace processing is not being performed.

localName - The local name (without prefix), or the empty string if Namespace processing is not being performed.

qName - The qualified name (with prefix), or the empty string if qualified names are not available.

atts - The attributes attached to the element. If there are no attributes, it shall be an empty Attributes object.

Throws:

SAXException - Any SAX exception, possibly wrapping another exception.

See Also:

ContentHandler.endElement(java.lang.String, java.lang.String, java.lang.String), Attributes

startDocument

public void startDocument()
                   throws SAXException

Reports an error if no Locator has been made available.

Overrides:

startDocument in class EventFilter

Following copied from interface: org.xml.sax.ContentHandler

Throws:

SAXException - Any SAX exception, possibly wrapping another exception.

See Also:

ContentHandler.endDocument()

endDocument

public void endDocument()
                 throws SAXException

Forgets about any base URI information that may be recorded. Applications will often want to call removeAllLinks(), likely after examining the links which were reported.

Overrides:

endDocument in class EventFilter

Following copied from interface: org.xml.sax.ContentHandler

Throws:

SAXException - Any SAX exception, possibly wrapping another exception.

See Also:

ContentHandler.startDocument()