attrimpl.java

用Java写的面相对象的数据库管理系统

/**
 * org/ozone-db/xml/dom/AttrImpl.java
 *
 * The contents of this file are subject to the OpenXML Public
 * License Version 1.0; you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 * http://www.openxml.org/license.html
 *
 * THIS SOFTWARE IS DISTRIBUTED ON AN "AS IS" BASIS WITHOUT WARRANTY
 * OF ANY KIND, EITHER EXPRESSED OR IMPLIED. THE INITIAL DEVELOPER
 * AND ALL CONTRIBUTORS SHALL NOT BE LIABLE FOR ANY DAMAGES AS A
 * RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. SEE THE LICENSE FOR THE SPECIFIC LANGUAGE GOVERNING
 * RIGHTS AND LIMITATIONS UNDER THE LICENSE.
 *
 * The Initial Developer of this code under the License is Assaf Arkin.
 * Portions created by Assaf Arkin are Copyright (C) 1998, 1999.
 * All Rights Reserved.
 */

/**
 * Changes for Persistent DOM running with ozone are
 * Copyright 1999 by SMB GmbH. All rights reserved.
 */

package org.ozoneDB.xml.dom;

import java.io.*;
import org.w3c.dom.*;
import org.w3c.dom.html.HTMLDocument;


/**
 * Represents an attribute in an {@link org.w3c.dom.Element} node.
 * <P>
 * Attributes are not real nodes, they are not children in their parent element
 * and the methods {@link AttrImpl#getParentNode}, {@link AttrImpl#getNextSibling}
 * and {@link #getPreviousSibling} always return null.
 * <P>
 * Attributes in XML documents support children, but only of the type {@link
 * org.w3c.dom.Text} and {@link org.w3c.dom.EntityReference}.
 * <P>
 * The specified value of an attribute indicates whether it's value has been
 * changed since it was constructed with the default value. The specified value
 * is not used when cloning an attribute or testing for equality.
 * <P>
 * To speed up implementation, all attributes are implemented as double-linked
 * list using {@link NodeImpl#_parent}, {@link NodeImpl#_nextNode} and
 * {@link NodeImpl#_prevNode}.
 *
 *
 * @version $Revision: 1.19 $ $Date: 2000/10/28 16:55:22 $
 * @author <a href="mailto:[e-mail]">Assaf Arkin</a>
 * @see org.w3c.dom.Attr
 * @see NodeImpl
 * @see ElementImpl
 */
public final class AttrImpl extends NodeImpl implements AttrProxy, Externalizable {
    
    final static long serialVersionUID = 1;
    
    
    public Element getOwnerElement() {
        throw new DOMException( DOMException.NOT_SUPPORTED_ERR,
                "ozone's persistent DOM doesn't support DOM level 2 yet." );
    } 
    
    
    public final short getNodeType() {
        return ATTRIBUTE_NODE;
    } 
    
    
    public final String getName() {
        return getNodeName();
    } 
    
    
    public final boolean getSpecified() {
        return _specified;
    } 
    
    
    public void setSpecified( boolean value ) {
        _specified = value;
    } 
    
    
    public String getValue() {
        return getNodeValue();
    } 
    
    
    public void setNodeValue( String value ) {
        super.setNodeValue( value );
        _specified = true;
    } 
    
    
    public void setValue( String value ) {
        super.setNodeValue( value );
        _specified = true;
    } 
    
    //    public Node getParentNode() {
    //        // Must return null per DOM spec.
    //        return null;
    //        }
    //
    //    public Node getPreviousSibling() {
    //        // Must return null per DOM spec.
    //        return null;
    //        }
    //
    //    public Node getNextSibling() {
    //        // Must return null per DOM spec.
    //        return null;
    //        }
    
    
    public String toString() {
        String value;
        
        value = getValue();
        if (value.length() > 32) {
            value = value.substring( 0, 32 ) + "..";
        } 
        return "Attribute node: [" + getName() + "] [" + value + (_specified ? "] SPECIFIED" : "]");
    } 
    
    
    protected boolean supportsChildern() {
        return true;
    } 
    
    
    public final Object clone() {
        AttrProxy clone = null;
        try {
            clone = (AttrProxy)database().createObject( AttrImpl.class.getName() );
            clone.init( _ownerDocument, getNodeName(), getNodeValue() );
            cloneInto( (NodeProxy)clone, true );
        } catch (Exception except) {
            throw new DOMExceptionImpl( DOMExceptionImpl.PDOM_ERR, except.getMessage() );
        } 
        return clone;
    } 
    
    
    public final Node cloneNode( boolean deep ) {
        AttrProxy clone = null;
        try {
            clone = (AttrProxy)database().createObject( AttrImpl.class.getName() );
            clone.init( _ownerDocument, getNodeName(), getNodeValue() );
            cloneInto( (NodeProxy)clone, deep );
        } catch (Exception except) {
            throw new DOMExceptionImpl( DOMExceptionImpl.PDOM_ERR, except.getMessage() );
        } 
        return clone;
    } 
    
    
    public synchronized void cloneInto( NodeProxy into, boolean deep ) {
        super.cloneInto( into, deep );
        ((AttrProxy)into).setSpecified( getSpecified() );
    } 
    
    
    /**
     * Assures that the children of an attribute are either {@link
     * org.w3c.dom.Text} or {@link org.w3c.dom.EntityReference}.
     *
     * @see NodeImpl#castNewChild
     */
    protected Node castNewChild( Node newChild ) throws DOMException {
        Node result;
        
        if (newChild == null) {
            throw new DOMExceptionImpl( DOMException.HIERARCHY_REQUEST_ERR, "Child reference is null." );
        } 
        if (!(newChild instanceof Text || newChild instanceof EntityReference)) {
            throw new DOMExceptionImpl( DOMException.HIERARCHY_REQUEST_ERR,
                    "Child is not a compatible type for this node." );
        } 
        return (Node)newChild;
    } 
    
    
    /** */
    public void writeExternal( ObjectOutput out ) throws IOException {
        super.writeExternal( out );
        out.writeBoolean( _specified );
    } 
    
    
    /** */
    public void readExternal( ObjectInput in ) throws IOException, ClassNotFoundException {
        super.readExternal( in );
        _specified = in.readBoolean();
    } 
    
    
    /**
     * Hidden constructor for attribute. Note that <TT>value</TT> is the DTD's
     * default value for this attribute, it is not the value specified in the XML
     * document. The value specified in the XML document should be passed by
     * calling {@link #setValue} explicitly.
     * <P>
     * The attribute name is case sensitive for XML, but is case insensitive and
     * all lower case for HTML documents. <TT>owner</TT> must point to a valid
     * document object.
     *
     * @param owner The owner document
     * @param name The attribute's name
     * @param value The attribute's value as specified in the DTD or null
     */
    AttrImpl( DocumentImpl owner, String name, String defValue ) {
        super( owner, owner instanceof HTMLDocument ? name.toLowerCase() : name, defValue, true );
        // Make sure that all attribute names are converted to lower case
        // for HTML documents.
        // Specified is always false. If a value was specified, it was the
        // default.
        _specified = false;
    }
    
    
    public AttrImpl() {
        super();
        _specified = false;
    }
    
    
    public final void init( DocumentProxy owner, String name, String value ) {
        super.init( owner, owner instanceof HTMLDocument ? name.toLowerCase() : name, value, true );
    } 
    
    /**
     * True if a value has been specified for this node in the document.
     * This value is not used when cloning or testing for equality.
     */
    private boolean _specified;
    
}