Filter
Top Products
60 The XML Files: Development of XML/XSL Applications Using WebSphere Studio
An application handles these events just as it would handle events from a
graphical user interface; there is no need to cache the entire document in
memory or secondary storage.
Currently, there are two versions of SAX: 1.0 and 2.0. Many changes were made
in version 2.0. The focus of this chapter is on SAX version 2.0. Most SAX parsers
should support the older 1.0 classes and interfaces, however, you will receive
deprecation warnings from the Java complier if you use these older features.
SAX2 classes and interfaces
The following interfaces and classes are provided by SAX2:
org.xml.sax.XMLReader which replaces SAX1 Parser
org.XML.sax.XMLFilter
org.xml.sax.ContentHandler which replaces SAX1 DocumentHandler
org.xml.sax.Attributes which replaces SAX1 AttributeList
org.xml.sax.SAXNotSupportedException
org.xml.sax.SAXNotRecognizedException
org.xml.sax.helpers.AttributesImpl which replaces SAX1 AttributeListImp
org.xml.sax.helpers.NamespaceSupport
org.xml.sax.helpers.XMLFilterImpl
org.xml.sax.helpers.ParserAdapter
org.xml.sax.helpers.XMLReaderAdapter
org.xml.sax.helpers.DefaultHandler which replaces SAX1 HandlerBase
SAX2 contains complete namespace support, which is available by default from
any XMLReader. AN XML reader can also optionally supply raw XML 1.0 names.
Have a look at “XML namespace support” on page 61 for more details about
SAX2 support for XML namespaces.
The ContentHandler and Attribute interfaces are similar to the deprecated
DocumentHandler and AttributeList interfaces, but they add support for the
namespace related information. ContentHandler also adds a callback for skipped
entities, and Attributes adds the ability to look up an attribute’s index by name.
The ContentHandler interface is regarded as the most important of the all, as it
has methods such as startDocument(), startElement(), characters(),
endElement(), and endDocument(). During the parsing process, startDocument()
is called once, then startElement() and endElement() are called once for each
tag in the XML data. The characters() method provides the text value of the
element. This process continues until the end of the document, at which time
endDocument() is called.
Since ContentHandler is an interface, it is up to your application code to
somehow implement this interface and subsequently do something when the
parser invokes its methods. SAX does provide a class called DefaultHandler that