BFO SAX/StAX Parser

A non-validating Java SAX / StAX parser that is designed for performance.

• Just plain faster. Even without the features below, benchmarking is roughly three times faster than Apache Xerces.

• Multi-threaded: XML reading is done in a secondary thread, with SAX events fired from the primary thread. This lets XML parsing continue in the background while your application processes startElement(), characters etc.

• Xerces caches DTDs based on the Public Id and resolved System Id. This implementation caches on the Public Id (by default, but this can be disabled) and on the checksum of the entity. This allows caching of DTD elements returned from a custom EntityResolver, even if there is no public or system ID specified. Checksumming is done with MurmurHash3, and is extremely fast.

While non-validating, it does parse DTDs to correctly evaluate entities, default attribute values and so on.

The XMLReader and its SAXParserFactory accept the following features:

• http://xml.org/sax/features/validation - recognised, but only accepts the default value of false.
• http://xml.org/sax/features/namespaces - true by default
• http://xml.org/sax/features/namespace-prefixes - true by default
• http://xml.org/sax/features/external-general-entities
• http://xml.org/sax/features/external-parameter-entities
• http://xml.org/sax/features/string-interning - doesn't use String.intern() of course; if set on will deduplicate strings using a local map.
• http://xml.org/sax/features/use-entity-resolver2
• http://apache.org/xml/features/nonvalidating/load-external-dtd
• http://apache.org/xml/features/disallow-doctype-dec
• http://bfo.com/sax/features/threads - on by default, turn off to parse without a secondary thread
• http://bfo.com/sax/features/cache - on by default, turn off to parse without any caching for DTDs or external entities
• http://bfo.com/sax/features/cache-publicid - on by default, turn off to not presume that a public-id on an external entity uniquely defines it
• http://javax.xml.XMLConstants/feature/secure-processing

The XMLReader and its SAXParserFactory accept the following properties:

• http://xml.org/sax/properties/lexical-handler
• http://xml.org/sax/properties/declaration-handler
• http://xml.org/sax/properties/document-xml-version
• http://apache.org/xml/properties/input-buffer-size
• http://javax.xml.XMLConstants/property/accessExternalDTD - which will default to the System property javax.xml.accessExternalDTD and functions as described by JAXP

StAX parser

The Jar includes an XMLInputFactory which can create an XMLStreamReader. This is built on the SAX parser code so has the same speed benefits.

The implementation shipping with Java 17 seems to have many bugs, so testing for API compliance is much harder. The XMLEventReader interface is there but untested, however as it's simply the addition of vast amounts of boilerplate code around XMLStreamReader it's likely to work to the same level.