/src/solidstack/xml/elements/StaxNodeReader.java

  1/*--
  2 * Copyright 2010 René M. de Bloois
  3 *
  4 * Licensed under the Apache License, Version 2.0 (the "License");
  5 * you may not use this file except in compliance with the License.
  6 * You may obtain a copy of the License at
  7 *
  8 *     http://www.apache.org/licenses/LICENSE-2.0
  9 *
 10 * Unless required by applicable law or agreed to in writing, software
 11 * distributed under the License is distributed on an "AS IS" BASIS,
 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 13 * See the License for the specific language governing permissions and
 14 * limitations under the License.
 15 */
 16
 17package solidstack.xml.elements;
 18
 19import javax.xml.stream.XMLStreamConstants;
 20import javax.xml.stream.XMLStreamException;
 21import javax.xml.stream.XMLStreamReader;
 22
 23import solidstack.lang.Assert;
 24import solidstack.lang.SystemException;
 25
 26
 27/**
 28 * Reads an element from an {@link XMLStreamReader}.
 29 *
 30 * @author René M. de Bloois
 31 */
 32@SuppressWarnings( "restriction" )
 33public class StaxNodeReader
 34{
 35	/**
 36	 * This utility class cannot be constructed.
 37	 */
 38	private StaxNodeReader()
 39	{
 40		super();
 41	}
 42
 43	/**
 44	 * Reads a element from the given {@link XMLStreamReader}.
 45	 *
 46	 * @param reader The {@link XMLStreamReader} to read a node from.
 47	 * @return The element that is read.
 48	 * @throws XMLStreamException When thrown by the {@link XMLStreamReader}.
 49	 */
 50	static public Element readNode( XMLStreamReader reader ) throws XMLStreamException
 51	{
 52		int event = reader.getEventType();
 53		Assert.isTrue( event == XMLStreamConstants.START_ELEMENT, "Expecting an element start" );
 54
 55		Element element = new Element( reader.getLocalName(), null );
 56		read( reader, element );
 57		return element;
 58	}
 59
 60	/**
 61	 * A recursive method to read elements from the {@link XMLStreamReader}.
 62	 *
 63	 * @param reader The {@link XMLStreamReader} to read a node from.
 64	 * @param element The element to populate with attributes and children.
 65	 * @throws XMLStreamException When thrown by the {@link XMLStreamReader}.
 66	 */
 67	static protected void read( XMLStreamReader reader, Element element ) throws XMLStreamException
 68	{
 69		for( int i = 0; i < reader.getAttributeCount(); i++ )
 70			element.addAttribute( reader.getAttributeLocalName( i ), reader.getAttributeValue( i ) );
 71
 72		StringBuilder buffer = new StringBuilder();
 73
 74		while( reader.hasNext() )
 75		{
 76			int event = reader.next();
 77			if( event == XMLStreamConstants.CHARACTERS )
 78			{
 79				if( !reader.isWhiteSpace() )
 80					buffer.append( reader.getText() );
 81			}
 82			else if( event == XMLStreamConstants.START_ELEMENT )
 83			{
 84				if( buffer.length() > 0 )
 85				{
 86					element.addText( buffer.toString() );
 87					buffer.setLength( 0 );
 88				}
 89
 90				Element child = new Element( reader.getLocalName(), element );
 91				element.addChild( child );
 92
 93				read( reader, child );
 94			}
 95			else if( event == XMLStreamConstants.END_ELEMENT )
 96			{
 97				if( buffer.length() > 0 )
 98				{
 99					element.addText( buffer.toString() );
100					buffer.setLength( 0 );
101				}
102				return;
103			}
104			else if( event == XMLStreamConstants.COMMENT )
105			{
106				// Ignore comments
107			}
108			else
109				throw new SystemException( "Unexpected event [" + event + "]" );
110		}
111	}
112}