org.geotools.xsd

Class StreamingParser

Object

StreamingParser

public class StreamingParser
extends Object

XML parser capable of streaming.

Performs the same task as Parser, with the addition that objects are streamed back to the client. Streaming can occur in a number of different modes.

As an example consider the following gml document:

 <test:TestFeatureCollection xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:gml="http://www.opengis.net/gml"
        xmlns:test="http://www.geotools.org/test"
        xsi:schemaLocation="http://www.geotools.org/test test.xsd">

   <gml:featureMember>
      <test:TestFeature fid="0">
              ...
      </test:TestFeature>
   </gml:featureMember>

   <gml:featureMember>
      <test:TestFeature fid="1">
              ...
      </test:TestFeature>
   </gml:featureMember>

   <gml:featureMember>
      <test:TestFeature fid="2">
              ....
      </test:TestFeature>
   </gml:featureMember>

 </test:TestFeatureCollection>
 

And suppose we want to stream back each feature as it is parsed.

1. Element Name

Objects are streamed back when an element of a particular name has been parsed.

    Configuration configuration = new GMLConfiguration();
    QName elementName = new QName( "http://www.geotools.org/test", "TestFeature" );

    StreamingParser parser = new StreamingParser( configuration, elementName );

    Feature f = null;
    while ( ( f = parser.parse() ) != null ) {
       ...
    }
  

2. Type

Objects are streamed back when an element has been parsed into an object of a particular type.

    Configuration configuration = new GMLConfiguration();
    StreamingParser parser = new StreamingParser( configuration, Feature.class );

    Feature f = null;
    while ( ( f = parser.parse() ) != null ) {
       ...
    }
  

3. Xpath Expression

Objects are streamed back when an element has been parsed which matches a particular xpath expression.

    Configuration configuration = new GMLConfiguration();
    String xpath = "//TestFeature";
    StreamingParser parser = new StreamingParser( configuration, xpath );

    Feature f = null;
    while ( ( f = parser.parse() ) != null ) {
       ...
    }
  

PullParser offers similar functionality out of a pull parser instead of a SAX parser, it's supposed to be better, but won't (yet) cover the entire functionality offered by StreamingParser

Author:

Justin Deoliveira, The Open Planning Project

Constructor Summary

Constructors

Modifier	Constructor and Description
	StreamingParser(Configuration configuration, InputStream input, Class type) Creates a new instance of the type based streaming parser.
	StreamingParser(Configuration configuration, InputStream input, QName elementName) Creates a new instance of the element name based streaming parser.
protected	StreamingParser(Configuration configuration, InputStream input, StreamingParserHandler handler) Internal constructor.
	StreamingParser(Configuration configuration, InputStream input, String xpath) Creates a new instance of the xpath based streaming parser.

Method Summary

Modifier and Type	Method and Description
Object	parse() Streams the parser to the next element in the instance document which matches the xpath query specified in the contstructor.
void	setEntityResolver(EntityResolver entityResolver)

Methods inherited from class Object

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

Constructor Detail

StreamingParser

public StreamingParser(Configuration configuration,
                       InputStream input,
                       Class type)
                throws ParserConfigurationException,
                       SAXException

Creates a new instance of the type based streaming parser.

Parameters:

configuration - Object representing the configuration of the parser.

input - The input stream representing the instance document to be parsed.

type - The type of parsed objects to stream back.

Throws:

ParserConfigurationException

SAXException

StreamingParser

public StreamingParser(Configuration configuration,
                       InputStream input,
                       QName elementName)
                throws ParserConfigurationException,
                       SAXException

Creates a new instance of the element name based streaming parser.

Parameters:

configuration - Object representing the configuration of the parser.

input - The input stream representing the instance document to be parsed.

elementName - The name of elements to stream back.

Throws:

ParserConfigurationException

SAXException

StreamingParser

public StreamingParser(Configuration configuration,
                       InputStream input,
                       String xpath)
                throws ParserConfigurationException,
                       SAXException

Creates a new instance of the xpath based streaming parser.

Parameters:

configuration - Object representing the configuration of the parser.

input - The input stream representing the instance document to be parsed.

xpath - An xpath expression which dictates how the parser streams objects back to the client.

Throws:

ParserConfigurationException

SAXException

StreamingParser

protected StreamingParser(Configuration configuration,
                          InputStream input,
                          StreamingParserHandler handler)
                   throws ParserConfigurationException,
                          SAXException

Internal constructor.

Throws:

ParserConfigurationException

SAXException

Method Detail

setEntityResolver

public void setEntityResolver(EntityResolver entityResolver)

parse

public Object parse()

Streams the parser to the next element in the instance document which matches the xpath query specified in the contstructor. This method returns null when there are no more objects to stream.

Returns:

The next object in the stream, or null if no such object is available.