structureddocumentutils.java

jxta_src_2.41b jxta 2.41b 最新版源码 from www.jxta.org

/*
 * Copyright (c) 2001 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
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 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: StructuredDocumentUtils.java,v 1.17 2006/03/29 22:45:53 bondolo Exp $
 */

package net.jxta.document;

import java.util.Enumeration;

/**
 *  Provides a number of static utility members which are helpful in
 *  manipluating StructuredDocuments.
 *
 **/
public final class StructuredDocumentUtils {
    
    
    /**
     *  A singleton class, not meant to be constructed
     **/
    private StructuredDocumentUtils() {;}
    
    /**
     * Recursively copy children elements of <code>from</code> into the
     * the element <code>intoElement</code> of document <code>intoDoc</code>.
     *
     * <p/><b>BEWARE</b> that this does NOT copy the TEXTVALUE (if any) of the
     * <code>fromParent</code> element, ONLY CHILDREN. All other elements
     * are fully copied, including their textValue.
     *
     * <p/>It is not possible to copy a textValue in an existing element.
     *
     * @param intoDoc  the document into which the elements will be
     * copied.
     * @param intoElement  the element which will serve as the parent for
     * the elements being copied.
     * @param from the parent element of the elements which will be copied.
     **/
    public static void copyChildren( StructuredDocument intoDoc, Element intoElement, Element from ) {
        
        for( Enumeration eachChild = from.getChildren();
        eachChild.hasMoreElements(); ) {
            
            Element aChild = (Element) eachChild.nextElement();
            Element newElement = intoDoc.createElement( aChild.getKey(), aChild.getValue() );
            intoElement.appendChild( newElement );
            
            // copy attributes if any
            if( (aChild instanceof Attributable) && (newElement instanceof Attributable) ) {
                Enumeration eachAttrib = ((Attributable)aChild).getAttributes();
                
                while( eachAttrib.hasMoreElements() ) {
                    Attribute anAttrib = (Attribute) eachAttrib.nextElement();
                    
                    ((Attributable)newElement).addAttribute( anAttrib.getName(), anAttrib.getValue() );
                }
            }
            
            // recurse to add the children.
            copyChildren( intoDoc, newElement, aChild );
        }
    }
    
    /**
     *  Recursively copy elements beginnging with <code>from</code> into the
     *  document identified by <code>intoDoc</code>.
     *
     *  @param intoDoc  the document into which the elements which will be
     *  copied.
     *  @param intoElement  the element which will serve as the parent for
     *  the elements being copied.
     *  @param from the root element of the hierarchy which will be copied.
     *  @param newName the root element being copied is renamed
     *  <em>newName</em>.
     *  @return The added element.
     *
     **/
    public static Element copyElements( StructuredDocument intoDoc, Element intoElement, Element from, Object newName ) {
        
        Element newElement = intoDoc.createElement( newName, from.getValue() );
        
        intoElement.appendChild( newElement );
        
        boolean hasType = false;

        // copy attributes if any
        if(newElement instanceof Attributable) {

            if (from instanceof Attributable) {
                Enumeration eachAttrib = ((Attributable)from).getAttributes();
            
                while( eachAttrib.hasMoreElements() ) {
                    Attribute anAttrib = (Attribute) eachAttrib.nextElement();
                    String attribName = anAttrib.getName();

                    if (attribName.equals("type")) {
                        hasType = true;
                    }
                    ((Attributable)newElement).addAttribute( attribName, anAttrib.getValue() );
                }
            }

            // If "from" happens to be a document, and if it happens to be renamed, and if it does not have an explicit type
            // attribute, then preserve the document type, which we assume is the original name, converted to string, as a type
            // attribute. It is an XMLism. It may be wrong or at least ineffective for other kinds of structured documents. If
            // it one day becomes an issue, it will have to be resolved by having a method specific to each kind of structured
            // document and dedicated to correcting type loss.

            Object origName = from.getKey().toString();
            if ((! hasType) && (! newName.equals(origName)) && (from instanceof Document)) {
                ((Attributable)newElement).addAttribute( "type", origName.toString() );
            }
        }

        StructuredDocumentUtils.copyChildren( intoDoc, newElement, from );
        
        return newElement;
    }
    
    /**
     *  Recursively copy elements beginnging with <code>from</code> into the
     *  document identified by <code>intoDoc</code>.
     *
     *  @param intoDoc  the document into which the elements which will be
     *  copied.
     *  @param intoElement  the element which will serve as the parent for
     *  the elements being copied.
     *  @param from the root element of the hierarchy which will be copied.
     *  @return The added element.
     **/
    public static Element copyElements( StructuredDocument intoDoc, Element intoElement, Element from ) {
        
        return copyElements( intoDoc, intoElement, from, from.getKey() );
    }
    
    /**
     * Copies the specified element or document into a standalone document of
     * same type. The <code>from</code element's name is used as the document
     * type. All child elements are recursively copied.
     *
     * @param from the root element from which to begin copying.
     * @return StructuredDocument the copy
     **/
    public static StructuredDocument copyAsDocument( Element from ) {
        
        StructuredDocument result;
        Object value = from.getValue();
        
        if (value == null) {
            result =
            StructuredDocumentFactory.newStructuredDocument(
                from.getRoot().getMimeType(),
                from.getKey().toString() );
        } else {
            result = StructuredDocumentFactory.newStructuredDocument( 
                from.getRoot().getMimeType(),
                from.getKey().toString(),
                value.toString() );
            value = null;
        }
        
        // copy attributes if any
        if( (from instanceof Attributable) && (result instanceof Attributable) ) {
            Enumeration eachAttrib = ((Attributable)from).getAttributes();
            
            while( eachAttrib.hasMoreElements() ) {
                Attribute anAttrib = (Attribute) eachAttrib.nextElement();
                
                ((Attributable)result).addAttribute( anAttrib.getName(), anAttrib.getValue() );
            }
        }
        
        StructuredDocumentUtils.copyChildren( result, result, from);
        
        return result;
    }
}