xml2objectparser.java

著名的开源仿真软件yale

/*
 *  YALE - Yet Another Learning Environment
 *  Copyright (C) 2002, 2003
 *      Simon Fischer, Ralf Klinkenberg, Ingo Mierswa, 
 *          Katharina Morik, Oliver Ritthoff
 *      Artificial Intelligence Unit
 *      Computer Science Department
 *      University of Dortmund
 *      44221 Dortmund,  Germany
 *  email: [e-mail]
 *  web:   http://yale.cs.uni-dortmund.de/
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as 
 *  published by the Free Software Foundation; either version 2 of the
 *  License, or (at your option) any later version. 
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 *  USA.
 */
package edu.udo.cs.yale.tools.xml;

import edu.udo.cs.yale.tools.LogService;

import java.io.*;
import org.kxml.Attribute;
import org.kxml.Xml;
import org.kxml.parser.XmlParser;
import org.kxml.parser.ParseEvent;
import org.kxml.parser.AbstractXmlParser;
import java.util.*;

/** This class is for parsing XML strings. Therefore it uses the kxml package of
 *  Stephan Haustein which is enclosed in YALE. <br>
 *  The constructor get a set of string pairs, whereby the first item of the pair is the tag's
 *  name and the second the proper class name. The classes must extend TagObject.
 *  <BR>
 *  <UL>
 *  <LI>During parsing a XML string for each tag the constructor of the proper class is 
 *      invoked. Thereafter, the set <CODE>setTagName()</CODE> is called with the name 
 *      of the tag.</LI>
 *  <LI>For each attribute the <CODE>setAttribute()</CODE> is invoked.</LI>
 *  <LI>For each inner tag recursively a new TagObject is created and added with
 *      <CODE>addInnerTag()</CODE></LI>
 *  <LI>For text the <CODE>appendText()</CODE> method is invoked.
 *  </UL>
 *  @see edu.udo.cs.yale.tools.xml.TagObject
 */
public class XML2ObjectParser {

    /** Verbosity Level for XML errors. */
    public int XML_VERBOSITY = LogService.ERROR;

    /** The classes for the tag names. */
    private Class[] tagClass;

    /** The tag names for the classes. */
    private String[] tagnames;

    /** Current line number, only used for error messages. */
    private int currentLineNumber;

    /** Creates a new XML2ObjectParser. */
    public  XML2ObjectParser(String[] tagnames, Class[] classes) {
	this.tagnames = tagnames;
	this.tagClass = classes;

	for (int i = 0; i < tagnames.length; i++) {
	    if (!TagObject.class.isAssignableFrom(tagClass[i])) {
		throw new IllegalArgumentException(tagClass[i].getName()+" is not a TagObject!");
	    }
	}
    }

    /** Parse a tag object from the reader and returns the first tag object. */
    public TagObject parseXML(Reader reader) throws XMLException, IOException {
	AbstractXmlParser parser = null;
	parser = new XmlParser(reader);
	return parseTag(parser);
    }

    /** Parse a all tag objects from the reader and returns them as list. */
    public List parseAll(Reader reader) throws XMLException, IOException {
	AbstractXmlParser parser = null;
	parser = new XmlParser(reader);
	List result = new LinkedList();
	TagObject tag = null;
	do {
	    tag = parseTag(parser);
	    if (tag != null)
		result.add(tag);
	} while (tag != null);
	return result;
    }

    /** Changes the parser to the TagObject suitable to the first containing Tag.
     *  Comments are ignored. */
    private TagObject parseTag(AbstractXmlParser parser) throws XMLException, IOException {
	ParseEvent event = null;
	event = parser.peek();
	currentLineNumber = parser.getLineNumber();
	
	switch (event.getType()) {
	case Xml.TEXT:
	    parser.read();
	    currentLineNumber = parser.getLineNumber();
		return new TextTagObject(event.getText());
	case Xml.START_TAG:
	    parser.read();
	    currentLineNumber = parser.getLineNumber();
	    for (int i = 0; i < tagnames.length; i++) {
		if (event.getName().equals(tagnames[i])) {
		    TagObject tagObject = null;
		    try {
			tagObject = (TagObject)tagClass[i].newInstance();
		    } catch (Exception e) {
			throw new XMLException(currentLineNumber+": Cannot instantiate '"+tagClass[i].getName()+"': " + e.getMessage());
		    }
		    tagObject.setTagName(event.getName());
		    for (int j = 0; j < event.getAttributeCount(); j++) {
			Attribute a = event.getAttribute(j);
			tagObject.setAttribute(a.getName(), a.getValue());
		    }
		    TagObject inner = null;
		    do {
			inner = parseTag(parser);
			if (inner != null) {
			    if (inner instanceof TextTagObject) {
				tagObject.appendText(((TextTagObject)inner).getText());				    
			    } else {
				tagObject.addInnerTag(inner);
			    }
			}
		    } while (inner != null);
		    event = parser.read();
		    currentLineNumber = parser.getLineNumber();
		    if (event.getType() != Xml.END_TAG) {
			throw new XMLException(currentLineNumber+ ": Missing end tag!");
		    }
		    return tagObject;
		}
	    }
	    throw new XMLException(currentLineNumber+": Unknown tag: "+event.getName());
	    
	case Xml.END_TAG:
	    return null;
	case Xml.WHITESPACE:
	case Xml.COMMENT:
	    parser.read();
	    currentLineNumber = parser.getLineNumber();
	    return parseTag(parser);
	default:
	    return null;
	}
    }

}