How do I handle errors?
You should register an error handler with the parser by supplying
a class which implements the org.xml.sax.ErrorHandler
interface. This is true regardless of whether your parser is a
DOM based or SAX based parser.
You can register an error handler on a DocumentBuilder
created using JAXP like this:
If you are using DOMBuilder
by supplying
a class which implements the org.w3c.dom.DOMErrorHandler
interface. For more information, refer to FAQ
You can also register an error handler on a SAXParser using JAXP like this:
Why does "non-validating" not mean "well-formedness checking" only?
Using a "non-validating" parser does not mean that only well-formedness checking is done! There are still many things that the XML specification requires of the parser, including entity substitution, defaulting of attribute values, and attribute normalization.
This table describes what "non-validating" really means for &ParserName; parsers. In this table, "no DTD" means no internal or external DTD subset is present.
non-validating parsers | validating parsers | |||
---|---|---|---|---|
DTD present | no DTD | DTD present | no DTD | |
DTD is read | Yes | No | Yes | Error |
entity substitution | Yes | No | Yes | Error |
defaulting of attributes | Yes | No | Yes | Error |
attribute normalization | Yes | No | Yes | Error |
checking against model | No | No | Yes | Error |
How do I more efficiently parse several documents sharing a common DTD?
By default, the parser does not cache DTD's. The common DTD, since it is specified in each XML document, will be re-parsed once for each document.
However, there are things that you can do to make the process of reading DTD's more efficient:
EntityResolver
and keep common
DTDs in a memory buffer.
How can I parse documents in a pull-parsing fashion?
Since the pull-parsing API is specific to Xerces, you have to use a Xerces-specific method to create parsers, and parse documents.
First, you need to create a parser configuration that implements the
XMLPullParserConfiguration
interface. Then you need to
create a parser from this configuration. To parse documents, method
parse(boolean)
should be called.
In the above example, a SAXParser is used to pull-parse an
XMLInputSource. DOMParser can be used in a similar way. A flag
continueParse
is used to indicate whether to continue
parsing the document. The application can stop the parsing by
setting this flag to false.
I would like to know more about the kind of entity my XMLEntityResolver's been asked to resolve. How can I go about convincing Xerces to tell me more?
XNI only guarantees that you'll receive an XMLResourceIdentifier object during an XMLEntityResolver#resolveEntity callback. Nonetheless, the xni.grammars package has a number of interfaces which extend XMLResourceIdentifier that can provide considerably more information.
To take advantage of this, you'll first need to see
whether the object you've been passed is an instance of
the
org.apache.xerces.xni.grammars.XMLGrammarDescription
interface. This interface contains a method called
getGrammarType
which can tell you what kind
of grammar is involved (for the moment, XML Schema and
DTD's are all that's supported). Once you know the type
of grammar, you can cast once again to either
org.apache.xerces.xni.grammars.XMLDTDDescription
or
org.apache.xerces.xni.grammars.XMLSchemaDescription
which contain a wealth of information specific to these
types of grammars. The javadocs for these interfaces
should provide sufficient information for you to know
what their various methods return.