Package org.gjt.xpp
This package defines classes compromising public API of XML Pull Parser 2.0 (org.gjt.xpp).
XmlEndTag | This represent XML end tag. |
XmlFormatter | This interface extends XmlRecorder to give some control
over formattingof XML output. |
XmlNode | This class represents XML subtree. |
XmlPullNode | This class represents pullable XML subtree - children are built on
demand. |
XmlPullParser | Generic interface for simple and quick XML Pull Parser. |
XmlPullParserBufferControl | Additional interface to control XML Pull Parser buffering. |
XmlPullParserEventPosition | Special interface to retrieve event positioning information. |
XmlRecorder | This class represents abstract functionality necessary to
to persist XML Pull Parser events. |
XmlStartTag | This class represents abstract functionality necessary to
to persist XML Pull Parser events. |
XmlTag | Base interface that encapsulates common functionality for
XML elements: both start tag and end tag
(an empty element is equivalent to start tag followed by
end tag so for simplicity ti is not modeled as a separate class). |
XmlWritable | This interface can be used by classes that wishes to implement
its own way to persist XML into writer. |
This package defines classes compromising public API of XML Pull Parser 2.0 (org.gjt.xpp).
Note this package is
deprecated by
next version of XML Pull Parser called XPP3/MXP1
that implements
XmlPull API.
Usage:
Xml Pull Parser (XPP) provides a simple and fast implementation of
"pull parsing model" that allows
processing application to request
parsing events
incrementally (ideal for deserializing XML such as SOAP encoding).
Following steps are required to use XPP:
- create an instance of
XmlPullParserFactory
using
newInstance() method
- create an instance of
XmlPullParser
using
newPullParser() method on instance of XmlPullParserFactory
- set options (if they are different than defaults)
- set input by calling either
XmlPullParser.setInput(Reader)
or
XmlPullParser.setInput(char[])
- start parsing by calling
XmlPullParser.next()
- this method returns event type and
parsing is finished when it returns
XmlPullParser.END_DOCUMENT
event type.
Typically parsing is done in
while loop that will
work until
XmlPullParser.next()
returns
XmlPullParser.END_DOCUMENT
event.
All possible types of events
that
XmlPullParser.next()
can return:
If there is parsing error
XmlPullParser.next()
will throw
XmlPullParserException
.
An example Java program may look like this:
(for more detailed example please see
src/java/samples/
)
// 1. creating instance of parser
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
XmlPullParser pp = factory.newPullParser();
// 2. setting options
// ex. disabling mixed content for elements
// (element can not have elements mixed with non-whitespace string content)
pp.setAllowedMixedContent(false);
// 3. setting input
String data = "<hello>World!</hello>";
// input will be taken from java.io.Reader
pp.setInput(new StringReader(data));
// input could be also taken from String directly:
//pp.setInput(data.toCharArray());
// 4. parsing
//declare variables used during parsing
byte type; // received event type
XmlStartTag stag = factory.newStartTag();
XmlEndTag etag = factory.newEndTag();
// start parsing loop
while((type = pp.next()) != XmlPullParser.END_DOCUMENT) {
if(type == XmlPullParser.CONTENT) {
String s = pp.readContent();
System.out.println("CONTENT={'"+s+"'}");
} else if(type == XmlPullParser.END_TAG) {
pp.readEndTag(etag);
System.out.println(""+etag);
} else if(type == XmlPullParser.START_TAG) {
pp.readStartTag(stag);
System.out.println(""+stag);
}
}
After parsing is finished, parser instance may be reused
by calling again
XmlPullParser.setInput(Reader)
.
Example Java code that will read string for SOAP encoding
public String readString(XmlPullParser pp, XmlStartTag stag)
throws DeserializeException, XmlPullParserException, IOException
{
String xs = stag.getAttributeValue(Soap.XSI_NS, "null");
if( "1".equals(xs) ) {
if(pp.next() != XmlPullParser.END_TAG)
throw new DeserializeException("expected end tag");
return null;
}
if(pp.next() != XmlPullParser.CONTENT)
throw new DeserializeException("expected content");
String content = pp.readContent();
if(pp.next() != XmlPullParser.END_TAG)
throw new DeserializeException("expected end tag");
return content;
}
Aleksander Slominski
<!-- Created: Thu Apr 14 18:21:21 EST 2000 -->
Last modified: $Id: package.html,v 1.4 2002/12/11 01:49:32 aslom Exp $
Copyright (c) 2003 IU Extreme! Lab http://www.extreme.indiana.edu/ All Rights Reserved.
Note this package is deprecated by XPP3 that implements XmlPull API