Stax 2 1 validating

SAX requires much less memory than DOM, because SAX does not construct an internal representation (tree structure) of the XML data, as a DOM does.

Instead, SAX simply sends data to the application as it is read; your application can then do whatever it wants to do with the data it sees.

This protocol is frequently used by servlets and network-oriented programs that need to transmit and receive XML documents, because it is the fastest and least memory-intensive mechanism that is currently available for dealing with XML documents, other than the Streaming API for XML (St AX).

Note - In a nutshell, SAX is oriented towards state independent processing, where the handling of an element does not depend on the elements that came before.

For faster development and simpler applications, one of the object-oriented XML-programming standards, such as JDOM ( and DOM4J ( might make more sense.

In real-life applications, you will want to use the SAX parser to process XML data and do something useful with it.

The following code handles the start-document and end-document events: public class SAXLocal Name Count extends Default Handler { private Hashtable tags; public void start Document() throws SAXException [...] public void end Document() throws SAXException private static String convert To File URL(String filename) { [...] method is invoked, to get the names and counts of the elements contained in the hash table, and print out a message onscreen to tell the user how many incidences of each element were found.

The first order of business is to process the command-line arguments, which at this stage only serve to get the name of the file to process.

The following code in the when it encounters problems, and defines the command-line options which are required to tell the application the name of the XML file to be processed.

Other command line arguments in this part of the code will be examined later in this chapter, when we start looking at validation. Characters found within the element are passed as an array of characters, along with the number of characters (length) and an offset into the array that points to the first character.

However, even if you plan to build DOM applications exclusively, there are several important reasons for familiarizing yourself with the SAX model: It is helpful to understand the SAX event model when you want to convert existing data to XML.

The key to the conversion process is to modify an existing application to deliver SAX events as it reads the data.

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