Hook of parsing

This section explains some utilities to parse XML document with SASAX.

Topics of this section are:

Notification of element determination
Notification of element start/end
Watching attributes

Notification of element determination

"AbstractElement", which is the base class of almost all "Elemenet" implementation classes, has "notifyDetermined(ParseContext)" method which is invoked when the content of element is determined.

For example, you can extend behavior of the "composite" element by overriding notifyDetermined(ParseContext) as shown below.


CompositeElement compositeElement =
    new CompositeElement(null, uri, "composite"){
        protected void notifyDetermined(ParseContext context){
            // processing on '</composite>' is placed here
        }
    };

Overriding of notifyDetermined(ParseContext)

Notification of element start/end

SASAX provides "Notification" interface to receive notification of element start/end.


public interface Notification
{
    public void elementStarted(Element element,
                               ParseContext context,
                               Attributes attributes)
        throws SAXException;

    public void elementEnded(Element element,
                             ParseContext context)
        throws SAXException;
}

Notification interface

AbstractElement has "addNotification()" method to register specified one into event receiver list.

Registered ones are invoked at corresponded element start/end. For example, you can receive start/end of "composite" element by below code:


compositeElement.addNotification(new Notification(){
    public void elementStarted(Element element,
                               ParseContext context,
                               Attributes attributes)
        throws SAXException
    {
        // processing on '<composite>' is placed here
    }

    public void elementEnded(Element element,
                             ParseContext context)
        throws SAXException
    {
        // processing on '</composite>' is placed here
    }
});

Registration of Notification

elementEnded() is invoked as soon as invocation of notifyDetermined(ParseContext), so almost all implementations in it can be placed in elementEnded() of Notification.

Watching attributes

ATTENTION: feature explained in this sub section is available since SASAX 1.5.

Somtimes attribute values described on start tag in XML document have important role. But you should keep attribute values, if you want to use it after the start of the element (e.g.: in elementEnded() of Notification, explained above).

AbstractElement assists your code to access attribute values after the start of the element by watchAttribute() and getAttribute().

You can have AbstractElement watch and keep attribute values by watchAttribute(). For example:


compositeElement.watchAttribute("", "foo");

watch and keep attribute value of "foo"

Now, compositeElement keeps attribute value of "foo"(without namespace) if it is described on the start tag in XML document.

You can get attribute value of "foo", which is described on start tag in XML document, by getAttribute() method.


compositeElement.getAttribute("", "foo");

get attribute value of "foo"

Attribute value is kept until clear() invocation, which is invoked at the (re)start of parsing by such element.

Without watchAttribute(), you can not get value of attribute, even though such attribute is described on start tag in XML document.

value on start tag	watching
value on start tag	watched	not watched
described	described value	`null`
not described	`null`	`null`

To next section "Element repetition"

Detailed information

Class names

In this tutorial, abbreviated class names are used. Complete names are shown below.

Notation	Full name
AbstractElement	jp.ne.dti.lares.foozy.sasax.AbstractElement
Element	jp.ne.dti.lares.foozy.sasax.Element
Notification	jp.ne.dti.lares.foozy.sasax.Notification
ParseContext	jp.ne.dti.lares.foozy.sasax.ParseContext

MAP