com.google.gdata.wireformats

Class XmlParser

java.lang.Object

org.xml.sax.helpers.DefaultHandler

com.google.gdata.wireformats.XmlParser

All Implemented Interfaces:

WireFormatParser, ContentHandler, DTDHandler, EntityResolver, ErrorHandler

public class XmlParser
extends org.xml.sax.helpers.DefaultHandler
implements WireFormatParser

XML parser, branched from XmlParser.

The plan is to integrate it tighter with the WireFormatParser interface, remove unnecessary interfaces and parameters (in our new data model, there is only one XmlParser.ElementHandler), and move it away from the util package.

Existing data classes continue to use the old XML parser until they've been migrated to the new data model, at which point they will start to use the new XML parser.

This is a thin layer on top of a SAX parser. The key concept necessary to understand this parser is Element Handler. Element handlers are type-specific parsers. Each handler instance contains an instance of the Java type corresponding to the XML type it parses. At any given time, one handler is active, and zero or more handlers are kept on the stack. This corresponds directly to the set of currently opened XML tags.

To use this parser, one must define an XmlParser.ElementHandler type (usually one per XML schema type), specify the root element handler, and pass a reader to the parse(Element) method.

See Also:

XmlParser.ElementHandler

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<String,Stack<com.google.gdata.wireformats.XmlParser.NamespaceDecl>>	namespaceMap Set of all namespace declarations valid at the current location.
protected StreamProperties	props Input properties for parsing
protected String	rootElementName Root element name.
protected com.google.gdata.wireformats.XmlParser.ElementHandler	rootHandler Root element handler.
protected String	rootNamespace Root element namespace URI.

Constructor Summary

Constructors

Constructor and Description
XmlParser(StreamProperties props, Reader r, Charset cs) Construct XML parser for given reader.
XmlParser(StreamProperties props, XmlEventSource eventSource) Construct XML parser for a given event source.

Method Summary

Methods

Modifier and Type	Method and Description
void	characters(char[] text, int start, int len) SAX callback.
protected XmlHandler	createRootHandler(ValidationContext vc, Element element, ElementMetadata<?,?> metadata) Create the xml handler for the root element.
void	endElement(String namespace, String localName, String qName) SAX callback.
void	endPrefixMapping(String alias) SAX callback.
void	ignorableWhitespace(char[] text, int start, int len) SAX callback.
Element	parse(Element element) Parse content from a source provided to the parser at construction time.
void	setDocumentLocator(Locator newLocator) SAX callback.
void	startElement(String namespace, String localName, String qName, Attributes attrs) SAX callback.
void	startPrefixMapping(String alias, String uri) SAX callback.
protected void	throwParseException(ParseException e) Throws a parse exception with line/column information.

Methods inherited from class org.xml.sax.helpers.DefaultHandler

endDocument, error, fatalError, notationDecl, processingInstruction, resolveEntity, skippedEntity, startDocument, unparsedEntityDecl, warning

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

props

protected final StreamProperties props

Input properties for parsing

rootHandler

protected com.google.gdata.wireformats.XmlParser.ElementHandler rootHandler

Root element handler.

rootNamespace

protected String rootNamespace

Root element namespace URI.

rootElementName

protected String rootElementName

Root element name.

namespaceMap

protected Map<String,Stack<com.google.gdata.wireformats.XmlParser.NamespaceDecl>> namespaceMap

Set of all namespace declarations valid at the current location. Includes namespace declarations from all ancestor elements.

Constructor Detail

XmlParser

public XmlParser(StreamProperties props,
         Reader r,
         Charset cs)

Construct XML parser for given reader.

Parameters:

props - stream properties for parsing

r - reader where input is retrieved from

cs - character set used to encode input

XmlParser

public XmlParser(StreamProperties props,
         XmlEventSource eventSource)

Construct XML parser for a given event source.

Parameters:

props - stream properties for parsing

eventSource - event source

Method Detail

parse

public Element parse(Element element)
              throws IOException,
                     ParseException,
                     ContentValidationException

Description copied from interface: WireFormatParser

Parse content from a source provided to the parser at construction time.

Specified by:

parse in interface WireFormatParser

Parameters:

element - root of parsed element tree

Returns:

root of parsed element tree

Throws:

IOException - if content cannot be accessed

ParseException - if content cannot be parsed invalid

ContentValidationException - if content fails metadata validation

createRootHandler

protected XmlHandler createRootHandler(ValidationContext vc,
                           Element element,
                           ElementMetadata<?,?> metadata)

Create the xml handler for the root element. Subclasses can supply their own parse handlers.

throwParseException

protected void throwParseException(ParseException e)
                            throws ParseException

Throws a parse exception with line/column information.

Throws:

ParseException

startElement

public void startElement(String namespace,
                String localName,
                String qName,
                Attributes attrs)
                  throws SAXException

SAX callback.

Specified by:

startElement in interface ContentHandler

Overrides:

startElement in class org.xml.sax.helpers.DefaultHandler

Throws:

SAXException

endElement

public void endElement(String namespace,
              String localName,
              String qName)
                throws SAXException

SAX callback.

Specified by:

endElement in interface ContentHandler

Overrides:

endElement in class org.xml.sax.helpers.DefaultHandler

Throws:

SAXException

characters

public void characters(char[] text,
              int start,
              int len)
                throws SAXException

SAX callback.

Specified by:

characters in interface ContentHandler

Overrides:

characters in class org.xml.sax.helpers.DefaultHandler

Throws:

SAXException

ignorableWhitespace

public void ignorableWhitespace(char[] text,
                       int start,
                       int len)
                         throws SAXException

SAX callback.

Specified by:

ignorableWhitespace in interface ContentHandler

Overrides:

ignorableWhitespace in class org.xml.sax.helpers.DefaultHandler

Throws:

SAXException

setDocumentLocator

public void setDocumentLocator(Locator newLocator)

SAX callback.

Specified by:

setDocumentLocator in interface ContentHandler

Overrides:

setDocumentLocator in class org.xml.sax.helpers.DefaultHandler

startPrefixMapping

public void startPrefixMapping(String alias,
                      String uri)

SAX callback.

Specified by:

startPrefixMapping in interface ContentHandler

Overrides:

startPrefixMapping in class org.xml.sax.helpers.DefaultHandler

endPrefixMapping

public void endPrefixMapping(String alias)

SAX callback.

Specified by:

endPrefixMapping in interface ContentHandler

Overrides:

endPrefixMapping in class org.xml.sax.helpers.DefaultHandler