An XML Pull Parser
The SAX API for parsing XML is called a "push-parsing” API because the SAX parser “pushes” tokens
or events to your code. It is also possible to parse XML using the
reverse architecture, in which your code “pulls” tokens from the XML
parser as needed. The TAX class of
Example 19-6 does just that.
TAX is an acronym for Trivial API
for XML. It is a pull parser (actually more of a fancy tokenizer) for
a subset of XML. Despite its simplicity, it is useful for a variety of
XML parsing tasks. The TAX.Parser
class relies on the Tokenizer
interface (defined in Example 2-8) and on the various
implementations of that interface (see Chapter 2, Chapter 3, and Chapter 6). The TAX class is simply a holder for inner
classes and token type constants. In addition to the TAX.Parser class, TAX also holds a Token class, a TokenType class (an enumerated type), and a
ParseException class.
Before diving into the details of the TAX parser, it is probably easiest to first
study how the parser is typically used. Example 19-5 is a program much
like the ListServlets program of
Example 19-1: it parses a
web.xml file and outputs the servlet
name-to-class mappings and name-to-URL mappings defined in the
file.
Example 19-5. ListServlets2.java
package je3.xml; import java.io.*; /** * Parse a web.xml file using the TAX pull parser and print out the servlet * name-to-class and name-to-url mappings. **/ public class ListServlets2 { public static void main(String[ ] args) throws IOException, TAX.ParseException ...Get Java Examples in a Nutshell, 3rd Edition now with the O’Reilly learning platform.
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