xdatafieldhandler.java

一款即时通讯软件

/*
 *   License
 *
 * The contents of this file are subject to the Jabber Open Source License
 * Version 1.0 (the "License").  You may not copy or use this file, in either
 * source code or executable form, except in compliance with the License.  You
 * may obtain a copy of the License at http://www.jabber.com/license/ or at
 * http://www.opensource.org/.  
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 *   Copyrights
 *
 *	 Shawn Wilton
 *
 *   Changes
 *
 * @author  Shawn Wilton <a href="mailto:[e-mail]">
 *                      <i>&lt;[e-mail]&gt;</i></a>
 *
 * @author  $Author: chris $
 * @version $Revision: 1.1 $
 *
 * j.komzak
 * Changed into XDataFieldHandler
 */

package edu.ou.kmi.buddyspace.xml;

/*
 * XDataFieldHandler.java
 *
 * Project: BuddySpace
 * (C) Copyright Knowledge Media Institute 2002
 *
 *
 * Created on 5 February 2003, 11:56
 */
import org.jabber.jabberbeans.Extension.*;
import org.jabber.jabberbeans.util.*;
import org.jabber.jabberbeans.*;
import org.jabber.jabberbeans.sax.SubHandler;
import org.xml.sax.SAXException;
import org.xml.sax.AttributeList;

/**
 * Handler class to build &lt;field&gt objects inside jabber:x:data
 *
 * @author  Jiri Komzak, Knowledge Media Institute, Open University, United Kingdom
 */
public class XDataFieldHandler extends SubHandler
{
	/** used to capture data between element tags */
	private StringBuffer elementChars;

	/** builder for XDataField objects */
	private XDataFieldBuilder builder;


	/*
	 * Creates a new <code>XDataFieldHandler</code> instance.
	 */
	public XDataFieldHandler()
	{
		super();
		builder = new XDataFieldBuilder();
	}


	/*
	 * This is an exact copy of the characters function in the main handler
	 *
	 * @param ch character string detected
	 * @param start start position
	 * @param length length of string
	 * @exception SAXException thrown on error
	 */
	public void characters(char[] ch, int start, int length) throws SAXException
	{elementChars.append(ch,start,length);}

	
	/**
         * Gets called when the underlying engine decides to pass an entity and
         * all sub-entities off to your subhandler.<p>
         *
         * Upon seeing the element that this subhandler handles, we call this
         * constructor, passing in the attributes.
         *
         * @param name name of the element which we are handling.
         * @param attributes list of attributes on this element
         */
        protected final void startHandler(String name,AttributeList attributes)
            throws SAXException
        {
            elementChars=new StringBuffer();
            builder.reset();
            
            builder.setType(attributes.getValue("type"));
            builder.setLabel(attributes.getValue("label"));
            builder.setVar(attributes.getValue("var"));
        }
    
        /*
	 * <code>handleStartElement</code> is overloaded by the new class to
	 * provide logic to handle the element code.
	 *
	 * @param name a <code>String</code> value
	 * @param attributes an <code>AttributeList</code> value
	 * @exception SAXException if an error occurs
	 */
	protected void handleStartElement(String name, AttributeList attributes) throws SAXException
	{			
		elementChars=new StringBuffer();

		//Start new handler for items that *may* be containers, but never for namespaces "ns".
		if ("value".equals(name) || "desc".equals(name))
                    //setChildSubHandler(new SingleValueTagHandler(), name, attributes);
                    return;
                
                else if ("option".equals(name))
                    setChildSubHandler(new XDataFieldOptionHandler(), name, attributes);
			
                else if ("required".equals(name))
                    builder.setRequired(true);
	}

        
	/*
	 * <code>handleEndElement</code> is overloaded by the new class to
	 * provide logic to handle element code.
	 *
	 * @param name a <code>String</code> value
	 * @exception SAXException if an error occurs
	 */
	protected void handleEndElement(String name) throws SAXException
	{
                if("value".equals(name))
                    builder.addValue(new String(elementChars));
                
                else if("desc".equals(name))
                    builder.setDesc(new String(elementChars));
	}

        
	/*
	 * Stophandler is the same as end element, except that it is called saying
	 * that the subhandler is no longer in scope.
	 *
	 * @param Object a value being returned to the parent - the parent is 
	 * meant to interpret this result.
	 */
	protected Object stopHandler(String name) throws SAXException
	{
		try{return builder.build();}
		catch (InstantiationException e)
		{
			e.fillInStackTrace();
			throw new SAXException(e);
		}
	}
	
	
	/*
	 * <code>receiveChildData</code> is called when a child handler exits,
	 * returning control to this code. The now-defunct handler along with the
	 * data object are both returned.
	 *
	 * @param subHandler a <code>SubHandler</code> value
	 * @param o an <code>Object</code> value
	 */
	protected void receiveChildData(SubHandler subHandler, Object o)
	{
		//Add the returned object to the child vector
		builder.addChild((XMLData)o);
	}
}