Processing XML

Processing existing XML

Groovy provides special XML processing support through the following classes:

Technology	When/Why to use	Requirements
XmlParser	supports GPath expressions for XML documents and allows updating	-
XmlSlurper	lower overheads than XmlParser due to lazy evaluation but only supports read operations	-
DOMCategory	low-level tree-based processing where you want some syntactic sugar	place `use(DOMCategory)` around your code

If you have special needs, you can use one of the many available Java APIs for XML processing:

Technology	When/Why to use	Requirements
DOM	low-level tree-based processing	-
SAX	event-based push-style parsing can be useful for streaming large files	-
StAX	event-based pull-style parsing can be useful for streaming large files	requires stax.jar
DOM4J	nicer syntax over DOM processing plus can be useful for large files if you use prune capability	requires dom4j.jar
XOM	nicer syntax over DOM processing plus a strong emphasis on compliancy	requires xom.jar
JDOM	nicer syntax over DOM processing	requires jdom.jar
XPath	use XPath expressions	-
Jaxen	use XPath expressions with slightly more efficiency than built-in XPath	requires jaxen.jar

For some more discussion of the pro's and con's of your XML Processing options and some additional details, see the following books:

The following articles may also be of interest:

The most used Groovy technique is to use one of:

Technology	When/Why to use	Requirements
StreamingMarkupWriter	for larger files	-
MarkupBuilder	supports Groovy's builder pattern with XML/HTML	-

You can also use XmlParser, DOM, DOM with category support, DOM4J, JDOM.